Storing Your Seed Phrase Safely: Metal Backups and Mistakes

Storing a seed phrase safely means: the 12 or 24 words are offline on stainless steel, complete and numbered, in a place only you control, separate from the wallet. Paper is fine to start with. For savings you need metal that survives fire and water, and one test that the recovery works.

Why almost all losses happen with the backup

Hackers don't crack seed phrases. Bitcoin get lost because the slip of paper ends up in the recycling during a move, because a word was copied wrongly, because the photo in the cloud is stolen or because the family doesn't know where it is.

Your wallet shows you the words exactly once, during setup. After that, everything depends on this one backup. Device broken, phone stolen, manufacturer bankrupt: with the words you restore your bitcoin in any compatible wallet. Without them you can't, and no one can help you.

What a seed phrase is and which kind of custody suits which amount is explained in the big custody guide. Here it is about the one question that follows: how do you keep the words so that they last for decades and still belong only to you?

Two dangers that pull against each other

Every seed backup has to do two things at once:

• It must not get lost. Against fire, water, forgetting and death, what helps is: sturdy material, a second copy, instructions for the family.
• It must not be found. Against burglars, curious visitors and scammers, what helps is: few copies, inconspicuous hiding places, nothing digital.

Every additional copy lowers the first risk and raises the second. You find the right point between them with the question: what is more likely for me, that I lose the words or that someone finds them? For most holders the answer is: lose them.

Paper or metal: which material survives what?

Paper is the right start. During setup you write the words with a ballpoint pen on the card that came with the wallet. For savings over years, paper is not enough: it burns, gets soaked, fades and gets thrown away.

A house fire at full blaze often reaches 800 to over 1’000 °C. The material of your backup should lie well above that.

Look for stainless steel, not just "steel". Ordinary steel rusts, and over time rust eats away stamped letters.

Which design: plate, capsule or washers

Metal backups come in three basic designs. They differ less in material than in how the letters are held in place.

Bitcoin developer Jameson Lopp heated, crushed and soaked 75 metal backups in a corrosive solution in stress tests. Solid stainless steel plates with punched or embossed letters almost all got the top grade. Designs with loose tiles did worse in the crush test, and some devices made of thin material failed completely. His grades per product are listed under the sources.

Making a metal backup in six steps

This is how you transfer your seed phrase from paper to metal without anyone seeing it:

1. Work alone and offline. No phone on the table, no camera in the room, no video call on the side.
2. Check the words against the word list. Every word must be in the BIP39 list. Easily confused are, for example, "sea" and "seat" or "fit" and "fix".
3. Transfer them numbered. Each word with its position, 1 to 12 or 1 to 24. The order matters.
4. Stamp cleanly. Practice on a test piece first. Every letter must be clearly legible, with no interpretation needed.
5. Restore from the metal. Reset a device or use your wallet's backup check and enter the words from the metal, not from the paper. If you see the same wallet with the same balance, the backup is correct.
6. Destroy the paper or keep it deliberately. Either tear it up and burn it, or store it as a second copy in a different place. Never just throw it in the wastebasket.

How to set up the wallet itself and do the first recovery test is shown step by step in the guide Setting up a bitcoin wallet.

How many copies, and where?

One copy in one place is a single point of failure: one fire, one water leak or one burglary, and it's gone. Two copies in two places are the better balance for most holders.

For the location: dry, inconspicuous, not next to the device. Anyone who finds device and seed together only needs the PIN. Not in the obvious safe in the bedroom, not in the folder labeled "Bitcoin".

A bank safe deposit box protects well against fire and burglary at home. In return, the bank knows you have a box, and you can only get to it during opening hours. With a trusted person, what matters is that they keep the envelope sealed and don't know what is inside. How to keep your home, mail and data low-profile is shown in the article Discretion and physical security for bitcoin holders.

What a metal backup costs in proportion

Most well-rated stainless steel backups cost between 20 and 150 euros or francs; a DIY version with washers and letter stamps about €20 to €40. That sounds like a lot for a few words, until you set it against what they protect.

What your holdings would be worth at today's floor, you can work out here:

Splitting the seed: why you never cut it in half

The idea is tempting: words 1 to 12 in one place, 13 to 24 in another. Then a single find is no use to anyone. That sounds safe, and it isn't.

• You double the risk of loss. If one half is missing, the whole seed phrase is worthless. Instead of one place that has to survive, there are two.
• With 12 words, you weaken the seed. Anyone who knows six words only has to try out the other six. That is a job for computing farms, no longer one for eternity.

If you really want to spread your keys over several places, use a method built exactly for that:

• Multisig: several complete seeds, for example 3, of which 2 are enough for a payment. If one is lost, the wallet stays accessible. How that works is explained in the article Multisig wallet: more security through several keys.
• Shamir backup (SLIP39): some hardware wallets generate several shares instead of one seed phrase, for example 2 of 3. A single share reveals nothing about your keys. Note: SLIP39 is a different standard from the usual seed phrase and is not compatible with every wallet.

The most common seed backup mistakes

• Photo or file. A picture in your gallery is automatically synced to the cloud. Whoever takes over your account has your bitcoin.
• Password manager or notes app. Even encrypted, that is a device with internet. A single stolen master password is enough.
• Typing the words into a website. Fake wallet sites and "support" forms want exactly that. You only enter the words into your own device, during a real recovery. The scams behind it are shown in the article Spotting bitcoin scams.
• No numbers, or incomplete. One missing or swapped word turns the recovery into a puzzle.
• Never tested. A typo only shows up when it's too late. Restore once, and then you know.
• Passphrase on the same sheet. If you use a passphrase, it belongs in a different place. Otherwise it doesn't protect anything.
• Multisig without the wallet descriptor. With multisig, the seeds alone are not enough. The wallet descriptor has to be with every seed.
• Seed next to the device. The burglar who finds both only needs the PIN.
• Nobody knows it exists. For your family, a perfect backup is worthless if they don't know where it is and what it is.

So that your family finds the backup

The safest hiding place has a drawback: it is hidden from your heirs too. So, separately from the seed, leave a letter saying what exists, where the words are and how to use them. The letter reveals the place, not the words.

How to keep your will, emergency letter and keys properly separate, so that your family gets to the coins and no stranger does, is shown in the article Inheriting bitcoin. You practice seed, passphrase and backups step by step in the academy, stage 2: Understand and secure.