How the draw is fair

You should not have to trust us. Every draw is built so that you can check it yourself, after the fact, with nothing but the numbers on your receipt.

Two seeds, one answer

Before you pay, we pick a secret random number, our seed, and show you its fingerprint: a code computed from the seed that cannot be reversed to find it. Then you pick your own seed. We can no longer change ours, because the fingerprint is already on your screen. You could not have known ours, because it is still secret.

The result is a fixed calculation of both seeds together. After the draw we reveal our seed. You check that its fingerprint matches the one you saw, then re-run the calculation and get the same roll we did.

The calculation

Combine your seed and the line number: yourSeed:lineNumber.
Sign it with our seed using HMAC-SHA256, a standard one-way hash. The result is 64 hex characters.
Take the first 13 hex characters. That is a whole number between 0 and 2⁵² − 1, evenly spread.
The item’s odds set a threshold: the chance to win, multiplied by 2⁵². If the roll is below the threshold, the spin wins.

A worked example

item: Rolex Submariner, retail $10,250, spin $51.25

chance = 0.65 × 51.25 / 10,250 = 0.00325 (1 in 308)

threshold = floor(0.00325 × 2^52) = 14,636,698,788,954

our seed (hex, 64 chars): a3f…9c1

fingerprint = SHA-256(our seed), shown before you paid

your seed: lucky-13, line 0

roll = first 13 hex of HMAC-SHA256(key = our seed, msg = "lucky-13:0")

roll = 0x0009fa3c11e2b = 2,747,395,310,123 → below the threshold → win

roll = 0x7b21d0aa93f04 = 2,166,738,456,301,316 → above → loss

What the odds mean

A spin costs half a percent of the retail value. Sixty-five cents of every dollar spent is, on average, paid back out as prizes over time; the house keeps thirty-five, before card fees. So on an item that costs us its retail value, the chance is 0.65 × 0.5% = 0.325%, about one in 308. If we can source an item below retail, the chance goes up. Every item page shows its exact figure, and that figure is frozen onto your order when you lock in.

One in 308 means most spins lose. Buying more spins buys more independent chances; it never improves any one of them.

Check one now

Open any receipt in your account and press Verify, or paste the numbers into the verifier. It runs entirely in your browser. The same maths in any language: HMAC_SHA256(serverSeed, `${clientSeed}:${nonce}`), first 13 hex digits, compare to the threshold.