Betting Maths Guides
Short, practical guides to the numbers behind a bet slip. Each one links to the calculator that does the sums for you.
How to use the calculatorsHow to use our betting calculatorsBetting odds explainedHow decimal, fractional and American odds work, how to turn any price into a return in naira and what the implied probability behind the odds tells youBookmaker marginWhat the bookmaker margin is, how to measure it from the odds of a market, why it grows in accumulators and how to compare prices between bookmakersAccumulator betsHow accumulator odds multiply, why each extra leg cuts your chance, how acca bonuses and void legs are settled, and how to check a slip before you place itSystem betsSystem and full-cover bets in one guideFree bets and rolloverHow free bets pay out, why the stake is usually kept, what a rollover requirement costs and how to judge a welcome bonus before you accept itMatched bettingHow backing and laying cancel each other out, what liability and commission mean, how a free bet is turned into cash and the limits of the methodHedging and cash outHow to hedge a running bet or acca, how a cash out offer compares with its fair value and when locking in a smaller sure profit is worth itArbitrage and dutchingHow surebets and dutching split one stake across several outcomes, how to spot an arbitrage from the odds and the practical risks before you try itValue betting and KellyWhat expected value means for a bet, how to estimate an edge honestly and how the Kelly criterion turns that edge into a stake size you can live withAsian handicapHow Asian handicap lines settleBankroll managementHow to set a betting bankroll, size each stake as a unit, survive losing runs and keep records, with naira examples and the limits that protect you
Where to start
If you are new to betting maths, read them in this order: how odds work, then the bookmaker margin, then accumulators. Together they explain most of what happens to your money on a slip.
Guides FAQ
Do I need maths to use the calculators?
No. The guides are for people who want to know why a result looks the way it does.
Are the guides about one bookmaker?
No. They explain general rules. Each bookmaker's own terms decide how a bet is settled.