Tool
Mines probability calculator
Choose the number of mines on a 5×5 board and the number of safe tiles you plan to reveal. The calculator shows the chance of surviving every pick, the fair multiplier (1 ÷ probability) and the multiplier after a house edge you set. It runs entirely in your browser.
—| Pick | Chance this pick is safe | Chance to get this far | Fair | With edge |
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The method
With m mines on 25 tiles, the chance that k picks are all safe is C(25−m, k) ÷ C(25, k): the number of ways to choose k tiles from the safe ones, divided by the number of ways to choose k tiles from all of them. The fair multiplier is 1 ÷ P. A game with a house edge of e pays (1 − e) ÷ P, so the expected return is always 1 − e, whatever you choose.
Check it in Python
from math import comb
def p_survive(m, k): return comb(25 - m, k) / comb(25, k)
p = p_survive(3, 5)
print(round(p, 4), round(1 / p, 4), round(0.99 / p, 4))
# 0.4957 2.0175 1.9974Real games may round multipliers or use a different edge, so the numbers on a site may differ slightly. For the full explanation, read the probability tables guide and fair vs house-edge multipliers.