Make a 24-word seed with dice

How a seed works

A seed is 24 words from a fixed list of 2048 words. Each word stands for 11 coin flips. That makes 23 words of pure chance, plus a last word.

The last word is special. Part of it is a built-in typo check, called the checksum. You can’t just pick it. It has to be calculated.

So the plan: dice choose words 1 to 23. An offline SeedSigner calculates word 24.

Never pick words yourself. People are bad at random. Thieves try “random-looking” word choices first.

Get ready

1. Print the official English word list. Number the lines 1 to 2048 if your print has no numbers.
2. Check the list: word 1 is abandon and word 2048 is zoo.
3. On paper, draw 23 rows of 11 boxes. Write these numbers above the columns: 1024, 512, 256, 128, 64, 32, 16, 8, 4, 2, 1.
4. Go somewhere private. No phones, cameras or smart speakers in the room.

Why casino dice? They are cut to exact sizes with sharp corners, so every side lands equally often. Cheap rounded dice can favour some numbers.

Roll for words 1 to 23

1. Roll one die for each box, left to right.
2. Rolled 1, 2 or 3? Write 0. Rolled 4, 5 or 6? Write 1.
3. Fill all 23 rows. That is 253 rolls, about 45 minutes.
4. If a die lands tilted against the edge, roll it again.

Never re-roll a result you don’t like. Every roll counts, even boring ones like many 0s in a row.

Turn each row into a word

Here is one example row:

1. Add up the column numbers above every 1. In the example: 512 + 256 + 8 + 2 + 1 = 779.
2. Add 1. The example becomes 780.
3. Find that number in the word list and write the word next to the row. In the example, line 780 is “gesture”.
4. Do all 23 rows. Then check every sum a second time.

A row of all 0s is word 1, “abandon”. A row of all 1s is word 2048, “zoo”. If your printed list starts at 0, skip the “add 1”.

Calculate word 24 on the SeedSigner

1. Start your SeedSigner. Choose Tools → Calc 12th/24th word (keyboard icon) → 24 words.
2. Enter words 1 to 23. Type the first letters, then pick the word.
3. Choose Coin flip entropy. It asks for 3 flips.
4. Roll the die 3 more times. 4, 5 or 6 = Heads = 1. 1, 2 or 3 = Tails = 0. Enter them.
5. SeedSigner shows the 24th word. Write it as word 24.

Only on an offline device. Never type your words into a phone, computer, website or app to find the last word. That exposes the seed forever.

Load the seed and note the fingerprint

1. Choose Next → Load seed.
2. Skip the passphrase option for now. Choose Done.
3. SeedSigner shows the fingerprint: 8 characters that name this seed. Write it with your words.

Test it before you fund it

1. Unplug the SeedSigner, then plug it back in.
2. Seeds → Enter 24-word seed. Type all 24 words from your paper.
3. The fingerprint must match. If not, a word or sum is wrong. Recheck your rows.
4. Connect it to Sparrow, receive a small amount and do a test send. Follow steps 11 to 17 of the SeedSigner guide.

Only then move more. A seed is only proven once you have received and spent with it.

Copy it onto steel

1. Number your steel slots 1 to 24.
2. Stamp or punch at least the first 4 letters of each word. In the BIP-39 list, the first 4 letters are always enough to tell words apart.
3. Test the steel copy: enter it into the SeedSigner from the steel only. Same fingerprint? Good.

Any reputable steel plate works. Look for stainless steel and letters you stamp or punch, not engrave by hand.

Store it and clean up

1. Keep the steel copy and the paper copy in two different safe places.
2. Never store them with your SeedSigner.
3. Burn your worksheet. The rows of 0s and 1s are your seed too.
4. Plan how your family would find your backup if something happened to you.

No photos, no cloud, no typing. Not even “just for a moment”. Not in a password manager either.