Methodology
How our numbers are calculated.
Every calculator on this site uses a stated formula and public data. Here they are, so you can check our work.
Lottery odds
A game with a main pool of N numbers from which k are drawn has C(N, k) = N! / (k! (N − k)!) combinations. With a bonus draw of b from M, multiply by C(M, b). Jackpot odds are one in that number. For a prize tier matching m main numbers and j bonus numbers, the probability is [C(k, m) × C(N − k, k − m) / C(N, k)] × [C(b, j) × C(M − b, b − j) / C(M, b)]. We check our results against published odds for Powerball (1 in 292,201,338), Mega Millions (1 in 290,472,336), EuroMillions (1 in 139,838,160), UK Lotto (1 in 45,057,474) and Lotto 6/49 (1 in 13,983,816), and our automated tests fail if they differ.
Several tickets and many draws
For n different tickets the jackpot chance is n divided by the number of combinations. For n random tickets, 1 − (1 − 1/C)ⁿ. Over d draws with n tickets, 1 − (1 − n/C)ᵈ, and the draws needed to reach a target probability P are ln(1 − P) / ln(1 − n/C).
US tax estimates
We use the 2026 federal income tax brackets and standard deductions from IRS Revenue Procedure 2025-32. The extra tax caused by a win is the tax on (other income + winnings − standard deduction) minus the tax on (other income − standard deduction), so a big prize is taxed at your marginal rates. The 24% withholding applies to prizes over $5,000. State tax is a flat rate you enter. We do not model deductions, credits, the alternative minimum tax or local taxes unless you include them in the rate.
Lump sum and annuity
The advertised jackpot is treated as the sum of 30 payments, each 5% larger than the last, so the first payment is jackpot × 0.05 / (1.05³⁰ − 1), about 1.5%. Each payment is taxed in its own year. Present value divides each year's take-home by (1 + discount rate) raised to the number of years elapsed.
Bitcoin mining odds
Your share of a block is h / (H + h), where h is your hashrate and H the network's, taken live from mempool.space. With about 144 blocks a day, blocks found follow a Poisson process with rate 144 × share per day, so the chance of at least one block in t days is 1 − e−144 × share × t and the expected wait is its reciprocal.
Winning-number statistics
Frequency tables count each number in every draw of the current format, from the State of New York's open data portal. We compare counts with the expected count (draws × numbers per draw / pool size) with a chi-square test, using the Wilson-Hilferty approximation for the p-value. The test is a sanity check that draws are consistent with chance, not a prediction.
The CryptoDrawz draw
Tickets in a draw are sorted and fingerprinted with SHA-256. The seed is SHA-256(drand value + ":" + fingerprint). For k = 0, 1, 2 …, the pick is the first eight bytes of SHA-256(seed + ":" + k), read as a number, modulo the ticket count, skipping repeats. See how to verify a draw.
Testing and limits
Our maths is covered by automated tests against published figures. All calculators are estimates for information. Formats, prices, tax rules and laws change, so check official sources before relying on a figure. See our editorial policy.