Metal Seed Phrase Backup: Complete Guide

Your Bitcoin seed phrase is the master key to your funds. Write it on paper and you are one house fire, one flood, or one curious family member away from losing everything. Metal seed phrase backups solve this problem by storing your recovery words on materials that survive the disasters paper cannot.

This guide compares the best-known metal backups, explains how to set them up correctly, and covers real-world durability testing so you can make an informed choice about protecting your bitcoin for the long term.

Why Metal Backups Matter

The standard backup method for a hardware wallet is writing your 12 or 24-word recovery phrase on the paper card that ships in the box (current Trezor Safe models default to a 20-word backup instead). This works fine until it does not. Paper degrades over time, is destroyed by water, burns in fires, and can be accidentally thrown away.

Consider the realistic threats to a paper seed backup:

• House fires: Average house fire temperatures reach 600 degrees Celsius (1,100 degrees Fahrenheit). Paper ignites at approximately 230 degrees Celsius (450 degrees Fahrenheit), so a paper backup caught in a fire will not survive it.
• Water damage: Flooding, pipe bursts, or even high humidity over years can render ink illegible on paper. Lose one word and recovery means typing the rest of your seed into a computer to search for it; lose several and your bitcoin may be gone for good.
• Physical degradation: Paper yellows, ink fades, and storage conditions matter more than most people realize. A seed phrase stored for 10+ years in a basement or attic may be partially or fully illegible when you need it most.
• Accidental destruction: Paper can be thrown away during moves, shredded by mistake, or damaged by pests. These are not hypothetical scenarios. They happen regularly.

Metal backups remove the first three of these risks, as long as the metal is stainless steel or titanium and the design holds the letters in place (the stress tests below show why that second condition matters). Stainless steel only starts to melt at around 1,400 degrees Celsius (2,550 degrees Fahrenheit), far above a house fire; it is impervious to water and will not degrade over decades of storage. Not every metal clears that bar: aluminum melts at about 660 degrees Celsius (1,220 degrees Fahrenheit), within the heat of a house fire, and aluminum cases melted in security researcher Jameson Lopp’s fire tests. Check that every part of a backup, case included, is stainless steel or titanium. For anyone holding meaningful amounts of bitcoin, a metal backup is not optional. It is the minimum standard for responsible self-custody.

Before choosing a metal backup method, make sure you understand the fundamentals of seed phrase security, including why your seed phrase is the single most important thing to protect in your entire Bitcoin setup.

Product Comparison: The Major Players

Here are the best-known products, from budget options to premium ones. Prices are from each maker’s own store on 7 November 2026; the durability grades are Jameson Lopp’s, from the stress tests described further down.

Cryptosteel Capsule, now sold as Seed24 ($80 list)

The Cryptosteel Capsule is a cylindrical stainless steel container that holds individual letter tiles on a core. You slide tiles onto the core to spell out each word of your seed phrase (using the first 4 letters of each BIP39 word, which is sufficient for unique identification). The core then goes inside the capsule, closed with a screw cap. Cryptosteel now sells it as the Seed24, which it calls “essentially the same product as the regular Capsule”: the same capacity, dimensions and materials, with a detachable core and numbered tamper-evident seals.

Material: Stainless steel. Cryptosteel calls it “space-grade” and says it uses AISI 303 for the tube and AISI 304 for the core and letter tiles.

Durability: Cryptosteel rates it for fire up to 1,400 degrees Celsius (2,500 degrees Fahrenheit). In Lopp’s tests the original Capsule kept every tile in place through the heat and lost nothing in acid. A 20-ton press bent the tube so the cap no longer unscrewed; Lopp judged the tiles inside intact but did not open it to check. Grade: A−.

Setup experience: Moderate difficulty. Sorting through hundreds of small letter tiles to find the ones you need is tedious. Plan for 30-60 minutes for initial setup. The tiles are small and easy to drop. Work on a clean, flat surface with good lighting.

Capacity: Up to 128 characters, enough for the first 4 letters of all 24 words, which uniquely identify every word in the BIP39 wordlist.

Price: $80 for the Seed24 Security Kit, on sale for $50 when we checked.

Its cylindrical form factor is compact and easy to store in a safe deposit box or a fire-rated safe. The main downside is the fiddly setup process with tiny tiles. For a direct comparison with the Billfodl, see our Cryptosteel vs Billfodl review.

Billfodl ($99)

The Billfodl is a flat stainless steel tray. Like the Capsule, it uses individual letter tiles, but they slide into rails instead of threading onto a core: 12 words on each side, each word in a numbered position and four words to a rail. A gate that you unlock with a flathead screwdriver keeps the tiles in, and a cover plate swings over them on a pivot. That is how the unit Lopp tested in 2018 looks in his photos.

Material: Marine-grade 316 stainless steel, with laser-engraved stainless steel tiles. Grade 316 resists corrosion better than the more common 304, particularly in salt-water environments.

Durability: Billfodl says it is built to withstand “more than double the average house fire”. Independent testing found a weakness in the part that holds the letters. In Lopp’s heat test the steel did not melt, but the tray warped and a number of letters fell out, which he counted as a catastrophic failure. A 20-ton press shook out nearly all of them. Acid had no effect. Grade: C (heat C, acid A, crush D).

Setup experience: Slightly easier than Cryptosteel because the flat layout makes it clearer where each tile goes. You need a flathead screwdriver to open the gate, and you still sort through small tiles. Plan for 20-45 minutes.

Capacity: Stores up to 24 words using the first 4 characters of each word.

The flat layout is easier to read and to fill than the Capsule’s tube. But loose tiles held only by a tray are its weak point, and surviving a fire is the main reason to buy metal. For a new backup, we recommend a punched plate or the Capsule instead.

Blockplate (out of stock)

Blockplate takes a fundamentally different approach. Instead of letter tiles, you use a center punch to press dots into a thick stainless steel plate printed with a grid of letters. Each word gets its own column, and you punch one dot per letter for its first four letters.

Material: 304 stainless steel plate, 11-gauge on its last product page. Thicker than the Cryptosteel or Billfodl, with no moving parts or small components.

Durability: Blockplate rated it for heat up to 1,149 degrees Celsius (2,100 degrees Fahrenheit). In Lopp’s tests it lost no data in heat, acid or the press. Grade: A. Because each letter is a dent in the metal rather than a loose tile, there is nothing to fall out or get out of order.

Setup experience: Different from tile-based products. You need a center punch: an automatic one marks with a firm press, a plain one needs a hammer. The physical act of punching is simple but requires care to hit the correct grid positions. A mistake means starting over with a new plate. Plan for 15-30 minutes.

Availability: Blockplate’s online store was unavailable when we checked on 7 November 2026, and its 24-word plate was already listed as sold out ($79) in January 2026. Check before you plan around it.

Blockplate’s advantage over tile-based products is that there are no loose parts. In Lopp’s tests the Billfodl’s tiles fell out in the heat and under the press; a punched plate’s dots cannot move because they are dents in the steel. This permanence is both a strength (nothing can fall out) and a weakness (mistakes are permanent).

Seedplate by Coinkite ($59.97)

Made by the same company behind the Coldcard hardware wallet, the Seedplate uses the same punched-grid approach as Blockplate. You use a center punch to mark the first four letters of each word on a steel plate printed with a grid of letters.

Material: 2 mm steel, cut and etched in Canada, with the letters chemically blackened so they are easy to read. Coinkite doesn’t publish the steel grade.

Durability: In Lopp’s tests the heat left only some discoloration and no data loss, the acid had no effect, and 20 tons of force bent it only a few millimetres. Grade: A.

Setup experience: Similar to Blockplate. Center punch approach with a grid layout. Clear instructions included.

Capacity: 24 words (12 per side), or 12 words on the smaller Tiny 12.

Price: $59.97 for the 24-word plate and $39.97 for the Tiny 12, plus $14.99 for Coinkite’s automatic center punch (sale prices; the 24-word plate lists at $69.99).

Of the two punched plates in this guide, the Seedplate is the one you can order today. It works with any BIP39 wallet; if you are already in the Coldcard ecosystem, it is a natural complement.

SAFU Ninja (DIY)

SAFU Ninja is not a product you buy but a do-it-yourself recipe: you stamp your letters into stainless steel washers with a letter punch set, stack the washers on a stainless steel bolt and close it with a cap nut. It is one of the most affordable options available and has gained a following in the Bitcoin community for offering solid durability at a low price point.

Material: A stainless steel bolt, cap nut and washers from any hardware store.

Durability: No letters lost in Jameson Lopp’s heat, acid and crush tests. The washers are loose parts, though, so number each one to keep the stack in order.

Setup experience: Slower than a punched plate: stamping letters into small, round washers takes patience.

Capacity: As many words as you stack washers.

SAFU Ninja proves that effective metal seed storage does not need to be expensive. For Bitcoiners on a tight budget, this is a perfectly functional option that dramatically outperforms any paper backup.

Comparison Table

Product	Price (7 Nov 2026)	Material	Maker’s fire claim	Lopp grade	Method	Loose Parts
Cryptosteel Capsule (Seed24)	$80 ($50 sale)	303/304 SS	1,400°C / 2,500°F	A−	Letter tiles	Yes (tiles)
Billfodl	$99	316 marine SS	No figure stated	C	Letter tiles	Yes (tiles)
Blockplate	Out of stock	304 SS	1,149°C / 2,100°F	A	Center punch	No
Seedplate	$59.97 (24 words)	2 mm steel	None stated	A	Center punch	No
SAFU Ninja	DIY	Stainless steel	None stated	A−	Letter stamps on washers	Yes (washers)

Fire claims are the makers’ own. Grades are Jameson Lopp’s overall grades from his heat, acid and crush tests (checked 7 November 2026). He gives an A to a test with no data lost; lower grades mark lost letters or a backup that is harder to read afterwards.

Tile-Based vs Stamped: Which Approach Is Better?

This is the most important design decision in the metal backup space, and it affects both setup experience and disaster resilience.

Tile-Based Products (Cryptosteel, Billfodl)

Advantages:

• Reusable: if you make a mistake or generate a new seed, you can rearrange the tiles
• Easier to read: individual letter tiles are immediately human-readable
• No punch or hammer needed

Disadvantages:

• Loose tiles can fall out if the case deforms: in Lopp’s heat test the Billfodl’s tray warped and letters fell out
• More complex setup with many small parts to sort and place
• Higher cost due to manufacturing many individual precision-cut tiles
• The container must maintain structural integrity for the tiles to remain in order

Stamped Products (Blockplate, Seedplate)

Advantages:

• Permanent: stamped marks cannot move, fall out, or become disordered
• No loose parts means nothing to scatter in a disaster
• Simpler construction with fewer potential failure points
• Generally less expensive
• Fastest setup once you understand the grid system

Disadvantages:

• Permanent: mistakes cannot be corrected. A wrong punch means starting over.
• Requires a center punch and a steady hand
• Slower to read back: each letter is a dot in a grid, read from the row it sits on
• Cannot be reused if you generate a new seed phrase

For pure disaster resistance, stamped products win. For ease of use and reusability, tile products win. Both approaches dramatically outperform paper. If you are backing up a seed phrase that you intend to use for years without changes, a stamped plate is the most robust choice. If you expect to rotate seeds periodically, a tile-based product offers more flexibility.

How to Set Up Your Metal Backup

Regardless of which product you choose, follow these security practices during setup.

Before You Start

1. Work in private. Set up your metal backup in a private room with no cameras, no windows facing public areas, and no other people present. Your seed phrase gives anyone who sees it full access to your bitcoin.
2. Disconnect from the internet. If you are referencing a wordlist on a computer, use an offline copy of the one your backup uses: BIP39 for 12 or 24 words, SLIP39 for a Trezor 20-word backup. Better yet, use a printed copy.
3. Verify your seed phrase first. Before committing it to metal, run your hardware wallet’s built-in backup check (Trezor’s Check backup or Ledger’s Recovery Check, for example): you type the words from your paper on the device, and it tells you whether they match without erasing anything. On a Trezor Model One, the standard check has you type the words on the computer instead, so choose Advanced recovery there: the computer never learns your words. Do not stamp a seed phrase you have not verified. Our backup test guide covers each brand.
4. Clear your workspace. Work on a clean, well-lit surface. For tile products, use a tray or towel to prevent tiles from rolling away. For stamped products, use a solid surface that can handle hammer strikes.

Setting Up a Tile-Based Backup (Cryptosteel or Billfodl)

1. Sort the letter tiles into alphabetical groups. This makes finding specific letters much faster.
2. For each word in your seed phrase, find the first 4 letters. The first 4 letters of any BIP39 word uniquely identify that word. For example, “abandon” becomes “ABAN” and “abstract” becomes “ABST.”
3. Slide or place the tiles into the corresponding slot for that word position.
4. After placing all tiles, read through the entire sequence to verify accuracy against your paper backup.
5. Secure the device: for Cryptosteel, screw the cap on firmly. For Billfodl, close the gate that holds the tiles in their rails, lock it with the screwdriver, and swing the cover plate back over the tiles.
6. Store the leftover tiles separately. Do not store them with the backup, as scattered tiles near a seed backup could aid an attacker in decoding it.

Setting Up a Stamped Backup (Blockplate, Seedplate)

1. Write down the first four letters of each seed word (the whole word if it has only three letters, like “act”). For example, “abandon” becomes ABAN.
2. Place the plate on a hard, solid surface. A concrete floor or anvil works well. A wooden table may dent.
3. Using the center punch, mark one dot per letter: in the column for that word, on the row of that letter.
4. Use moderate, controlled strikes. One clean hit per position is better than multiple light taps.
5. After stamping all words, verify each position against your original seed phrase by reading back the letters and matching them to your words.
6. Double-check everything. A single misplaced dot could make recovery impossible.

Storage Best Practices

A metal backup that sits next to your hardware wallet in a desk drawer defeats the purpose. Proper storage requires geographic separation and physical security.

• Separate locations: Store your metal backup in a different physical location from your hardware wallet. If both are in your home, one burglar can find both, and the plate alone is enough to take your bitcoin. A safe deposit box, a trusted family member’s safe, or a second property are all valid options.
• Fire-rated safe: A well-designed metal backup survives a house fire on its own, but a fire-rated safe keeps it out of casual view, and a heavier safe bolted down also slows a burglar.
• Consider a passphrase: If you use a BIP39 passphrase (25th word), someone who finds your metal backup still cannot access your funds without the passphrase. This adds a layer of security that makes geographic distribution safer.
• Multiple backups: For significant holdings, consider making two metal backups and storing them in different locations. The cost of a second backup ($40-$100) is trivial compared to the bitcoin it protects.
• Do not label it: Do not write “Bitcoin seed phrase” or “crypto backup” on or near your metal backup. Plausible deniability matters. A plain metal plate in a safe deposit box attracts far less attention than one labeled with its purpose.

Independent Fire, Acid and Crush Testing

Jameson Lopp, a well-known Bitcoin security researcher, has stress-tested dozens of metal seed storage devices and published the results. In his current method, each device faces a propane torch flame of about 1,093 degrees Celsius (2,000 degrees Fahrenheit) for up to 10 minutes, followed by a plunge into a bucket of water; up to 12 hours in hydrochloric (muriatic) acid; and a 20-ton hydraulic press. The products in this guide were tested in rounds he published between July 2018 and August 2020. The first round, which included the Billfodl, used a butane torch and a shorter acid bath. A product may also have changed since it was tested.

Key findings from stress testing:

• The steel survived the heat; one design did not. None of the five products in this guide melted, but the Billfodl’s tray warped enough to loosen its letters and a number of them fell out, which Lopp counted as a catastrophic failure. The Cryptosteel Capsule came through the heat with every tile in place.
• Tile-based products are only as strong as their case. Under the 20-ton press, the Billfodl lost nearly all of its letters. The Capsule’s tube bent and the cap could no longer be unscrewed. Lopp judged the tiles inside intact but did not open it: reading them would mean cutting the tube open without letting tiles slip off the rod.
• Punched plates lost nothing. Blockplate and Seedplate came through heat, acid and the press with no data loss. Because each letter is a dent in the metal, nothing can fall out, and the dots stay put short of the steel melting (which requires temperatures no house fire reaches).
• Corrosion had no effect on any of the five, whatever the design. An acid bath far harsher than any flood did not cost any of them a letter.

The bottom line: stainless steel itself survives any realistic disaster. What can fail is the part of a design that holds the letters in place, which is why loose tiles need a sturdy case and punched plates need none. Even the cheapest stamped plate dramatically outperforms the best paper backup.

Which Metal Backup Should You Buy?

Best overall: a punched plate. Seedplate ($59.97 for 24 words, plus a center punch) scored A in all three of Lopp’s tests and is in stock. Blockplate did as well, but its store was unavailable when we checked on 7 November 2026. With no loose parts, there is nothing to fall out in a fire or under a crushing weight.

Best budget option: the Seedplate Tiny 12 ($39.97) for a 12-word seed, or SAFU Ninja (DIY). SAFU Ninja is the do-it-yourself route, with letters stamped into washers, and it lost no letters in Lopp’s tests (grade A−).

Best tile-based: Cryptosteel Capsule, now sold as the Seed24 ($80 list, $50 on sale when we checked on 7 November 2026). It kept every tile in place through Jameson Lopp’s heat test, where the Billfodl’s tray warped and letters fell out. If you prefer the readability and reusability of tiles, the Capsule is the one to get.

Best for multiple seeds: If you run a multisig setup with multiple seed phrases to back up, punched plates are the most cost-effective approach. Three 24-word Seedplates cost about $180 at the 7 November 2026 sale price, and one $14.99 center punch marks all three. Every plate scored A in Lopp’s tests, which makes them a good fit for a 2-of-3 multisig setup.

No matter which product you choose, the most important thing is that you actually use one. A $40 metal backup protecting a significant Bitcoin holding is one of the highest-value security investments you can make. And once your metal backup is in place, verify it works by typing the words from the metal into your hardware wallet’s built-in backup check, as our backup test guide explains.

Frequently Asked Questions

Do I need to store all 24 words or just the first 4 letters of each?

The first 4 letters of each BIP39 word uniquely identify that word from the entire 2,048-word wordlist. No two words in the BIP39 list share the same first 4 letters. So “ABAN” can only mean “abandon,” and “ABST” can only mean “abstract.” Most metal backup products use this 4-letter approach because it saves space while maintaining perfect recoverability. The same holds for the 1,024-word SLIP39 list behind Trezor’s 20-word backups: every word is at least 4 letters long and no two share the same first 4 letters. A Trezor multi-share backup is several 20-word shares, so give each share its own plate and its own location.

Can I make my own metal backup instead of buying a commercial product?

Yes. Some Bitcoiners buy plain stainless steel plates or washers and a letter punch set from a hardware store for under $30 total. Jameson Lopp has stress-tested several do-it-yourself designs, and they did well: SAFU Ninja, stamped washers on a bolt, lost no letters in his heat, acid and crush tests. A commercial plate saves you the stamping and gives you a neater grid. What matters most is the design, not the brand: some commercial products scored worse in his tests than the DIY ones.

Should I store my passphrase on the same metal backup as my seed?

No. The entire point of a passphrase is that it serves as a second factor separate from your seed. If someone finds a metal backup containing both the seed phrase and the passphrase, the passphrase provides zero additional security. Store the passphrase separately, ideally in a different location and on a different medium.

How often should I verify my metal backup is still readable?

Annually is sufficient. Stainless steel does not degrade under normal storage conditions, so this is more about verifying the backup is still where you left it and has not been tampered with. If you store it in a safe deposit box, check it during your annual box visit.

Is a fireproof safe sufficient without a metal backup?

Fireproof safes are rated for specific temperatures and durations (typically 1 hour at 927 degrees Celsius for good models). In a severe fire that burns longer than the rating, a fireproof safe can fail, and the paper inside is destroyed. A metal backup inside a fireproof safe gives you two layers: the safe keeps the plate out of casual view and shields it from short fires, and the metal is what still holds your words if a long fire defeats the safe. Using both together is the recommended approach. A fire rating says nothing about theft, though: only a heavy safe bolted down, or one with its own burglary rating, slows a burglar.

What about titanium seed storage products?

Titanium has a higher melting point than stainless steel (1,668 degrees Celsius vs roughly 1,400 degrees Celsius) and is more corrosion resistant. Some manufacturers offer titanium plates at a premium price. For practical purposes, the difference is academic. No house fire will reach temperatures that threaten either material. Save the money and buy stainless steel unless you are protecting against threats that go well beyond normal disaster scenarios.