Cold storage means your private keys have never touched an internet-connected computer. That is the whole idea. Everything else - the devices, the metal plates, the ritual around seed phrases
- is machinery built to serve that one sentence.
What a hardware wallet actually does
It is not a container. Your bitcoin is not "on" the device, and if the device is destroyed your coins are not destroyed with it. The blockchain holds the coins; the device holds a secret that proves they are yours to move.
When you spend, your computer builds an unsigned transaction and hands it to the device. The device shows you the amount and destination on its own small screen, you approve on its own buttons, and it hands back a signature. The key never leaves. That is why a compromised laptop cannot drain a hardware wallet - though it can absolutely show you a swapped address, which is why you check the address on the device screen and not on the monitor.
Which one
Any of these is fine, and the differences matter far less than actually using one:
- Coldcard - bitcoin-only, air-gapped workflow via SD card, the choice of people who enjoy this. Steepest learning curve.
- Trezor Safe - open source, straightforward, well documented.
- Ledger - the most common, good hardware, closed firmware and a corporate history that irritates people. Still far better than an exchange balance. Our full review, including the parts Ledger would rather we left out.
- Blockstream Jade - inexpensive, bitcoin-only, open source.
- SeedSigner - you build it yourself from commodity parts and it stores nothing at all.
Buy directly from the manufacturer. Never from a marketplace listing, never secondhand, never one that arrives already set up with a seed phrase printed on a card. That last one is a known scam and it is convincing.
The seed phrase is the wallet
On setup the device shows you twelve or twenty-four words. Those words are your bitcoin. Any device anywhere in the world, from any manufacturer, can reconstruct your entire wallet from them. That cuts in both directions and it is the single thing to get right.
Write them on paper, then get them onto metal. Paper survives most things but not fire or a burst pipe, and both are more common than burglary. A stamped steel plate costs about £30 and removes the whole category.
Never photograph or type them. Not into a password manager, not into a notes app, not into cloud storage, not into a "temporary" text file. Every one of those has lost people money. If it has ever been on an internet-connected device, treat it as compromised.
Test the backup before you fund it. Set the device up, write the words, wipe the device, restore from the words. Only when the restore works do you send real money. Almost nobody does this and it catches a shocking number of transcription errors - a misread word, two words swapped, one line skipped.
The honest risk ranking. Far more bitcoin has been lost to bad backups than to hackers. Your threat model is not a state actor; it is you, in six years, trying to remember which drawer the card went in, and a family who do not know the drawer exists.
Where to keep it
The device and the seed phrase should not live in the same place. If they do, one burglary or one fire takes both.
A reasonable setup for most people: device at home, metal backup at a parent's house or in a bank deposit box. A more paranoid setup splits the seed across locations, but split schemes invented at the kitchen table are how people lock themselves out permanently. If you want redundancy beyond two locations, use a real multisig setup rather than an improvised one.
The passphrase question
Hardware wallets support an optional extra word - a "passphrase" or "25th word" - that creates an entirely separate wallet. It is genuine protection against someone who finds your seed phrase.
It is also a superb way to lose everything. The passphrase is not stored anywhere. Forget it and the coins are gone with no recovery path, and unlike the seed phrase there is no standard convention for how to back it up. Skip it unless you have a specific threat you are defending against and a written plan for how your heirs will ever find it.
What cold storage does not solve
It protects against theft and exchange failure. It does nothing about three other problems:
- You selling at the wrong moment. The keys are in the drawer and the drawer opens. If your problem is discipline rather than security, cold storage is not the tool - a timelock is.
- You dying. A hardware wallet nobody can find is indistinguishable from coins that never existed. That needs an actual plan.
- You forgetting. Check your backup once a year. Put it in the calendar.
For the difference between locking coins away from thieves and locking them away from yourself, see timelock versus cold storage.