Storing a seed phrase well means solving two problems that pull in opposite directions: it has to survive you losing it, and it has to survive someone else finding it. Optimise only for the first and you end up with copies everywhere. Optimise only for the second and you end up with one perfectly hidden backup that nobody — including you, in ten years — can produce.
Almost every storage question resolves once you decide which of those two you are actually more likely to face. For most people it is the first one. Seed phrases are lost far more often than they are stolen.
Start with the threats that are real
A storage plan is only sensible relative to a threat list. Here is an honest one, roughly in order of how often it actually bites people:
- You lose it or forget where it is. Moves, deaths, decluttering, a “safe place” nobody remembers.
- It degrades. Ink fades, thermal paper goes blank, damp destroys paper, pencil smudges.
- Fire or flood. Rarer, but total.
- Casual discovery. A guest, a cleaner, a contractor, a family member finds an envelope marked “crypto”.
- Targeted theft. Someone who knows you hold crypto and comes looking.
- Coercion. Rare, and the only threat on this list where a well-hidden backup does not help you.
Notice that four of the six are about loss, not theft. That is why the single most common mistake is keeping exactly one copy.
Paper is a floor, not a plan
The card that came in your hardware wallet box is fine for a week. It is not a decade-scale backup, for a physical reason worth knowing: paper ignites at roughly 220–250 °C, while a house fire commonly runs 600–1,000 °C. A domestic fire does not merely singe a paper backup; it removes it.
If you are using paper anyway, at least do these:
- Write in pencil or a pigment-ink pen, not ballpoint or gel — pencil graphite does not fade or run.
- Never use a receipt or thermal paper. It self-erases with heat and age.
- Write in block capitals, numbered 1 to 12 or 1 to 24. Order is part of the secret.
- Keep it flat and dry, in a sealed bag, away from sunlight.
Metal, and why it is the default for anything long-term
Stainless steel melts somewhere around 1,400 °C — comfortably above what a house fire produces. It also does not care about water, humidity, insects or time. That is the entire pitch, and it is a good one.
The formats fall into three groups, and the trade-off is always speed of setup against resistance to being read:
- Stamped plates. You hammer letter punches into steel. Slow, permanent, cheap, and effectively indestructible.
- Tile or washer systems. Pre-engraved letter tiles you slot into a holder. Fast, reusable, and the most likely to be assembled wrongly if dropped.
- Engraved or etched cards. Fast with a rotary tool, but shallow marks can be polished away by heat and abrasion.
Only the first four letters of each BIP-39 word are needed to identify it uniquely, which is why most metal kits give you four columns per word. That is a real space saving, not a shortcut.
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How many copies, and where
Two copies in two buildings is the sensible default for most people. One copy is fragile. Five copies is five things to secure and five chances to be found.
Reasonable locations: a home safe that is bolted down, a trusted relative’s house, a second property. A bank safe deposit box works for fire and theft but adds a real inheritance problem — access after a death can take months and a court order, which is exactly when your family needs it. Treat it as one leg of a plan, never the only one.
Two locations that feel clever and are not: a car (heat, theft, write-offs) and a workplace desk (you may leave that job faster than you expect).
Where it must never go
Anything digital, connected, or synced is out. Specifically:
- Photos. Your camera roll syncs to a cloud account protected by a password and a phone number — both of which are attackable in ways your seed phrase is not.
- Cloud notes and documents. Same problem, plus full-text search makes “seed phrase” trivially findable by anyone who gets in.
- Email to yourself. Permanent, searchable, and copied across every device you ever signed in on.
- Messaging apps, including messages to yourself.
- Password managers. More defensible than the rest, and genuinely better than nothing — but it collapses your security into one master password, and a compromise of that vault now costs you your crypto as well as everything else.
The general rule: a seed phrase should never exist on a device that has ever been online.
Splitting the phrase: mostly a trap
A tempting idea: write words 1–6 on one card, 7–12 on another, store them apart. Now no single find gives up the wallet.
It is weaker than it looks, in both directions.
It does not halve the security — it guts it. A 12-word phrase carries 128 bits of entropy. Someone holding half the words does not face 2128 guesses; they face roughly 262 after the checksum constrains the possibilities. That is still a big number, but it has moved from “impossible for anyone, ever” into a range that well-funded, patient attackers can reason about. You have converted an unbreakable secret into a merely difficult one.
And it doubles your loss risk. Now either half going missing loses everything. You have taken the most common failure mode and made it twice as likely.
If genuine splitting is what you want, the correct tool is a proper threshold scheme — Shamir-style backups, where you define something like “any 2 of 3 shares reconstruct the secret, and 1 share reveals nothing at all”. Some hardware wallets implement this natively. It gives you redundancy and secrecy, which naive splitting gives you neither of.
Labels, and the mistake of hiding too well
Do not write “Bitcoin seed phrase — Ledger” on the envelope. Equally, do not make it so anonymous that it gets thrown out as junk, or so hidden that nobody finds it when you are gone.
The workable middle: the backup itself is unlabelled and unremarkable, and a separate document — kept with your will or your important papers — says that it exists, roughly where, and who should be told. That document never contains the words. See inheritance for how to write it.
The step nearly everyone skips
An untested backup is a guess. Transcription errors are common, order mistakes are common, and you will not discover either at the moment you need them.
Test it properly before you rely on it — and never by typing it into a website. This is important enough to have its own page.
One standing rule here: no tool on SteelPhrase will ever ask you to enter a recovery phrase, and neither should anything else you did not personally go looking for.