Simple Overround Calculator For 2026

What The Overround Calculator Works Out

• Book total: every outcome's decimal odds converted to an implied probability (1 divided by the odds) and added up. A fair market sums to exactly 100%; odds of 2.0, 3.5 and 4.0 on a three-way market sum to 103.6%.
• Bookmaker margin: the book total minus 100%. Major football match odds at big firms run 2% to 5%, exchanges effectively 0% plus commission, while racecards, correct scores and specials can carry 20% to 40%. Beating a 5% margin long term means being 5% better than the market.
• Fair odds: each price lengthened in proportion so the book comes to exactly 100%, which is the honest benchmark to judge a price against.
• Result of backing every outcome (advanced): spreads your stake across all outcomes in inverse proportion to the odds (the dutching arithmetic). With an overround this locks in a loss equal to the margin; a book under 100% across different bookmakers would lock in a profit, though such arbs are small, brief and a well-known route to account restrictions.
• Margin after commission (advanced): exchange odds look margin-free but 2% to 5% commission on winnings is an equivalent cost. The card recalculates the book using net odds after commission.
• Margin compounded in an acca (advanced): accumulator legs multiply their margins: four legs at 5% each is a 21.6% combined take, eight legs about 48%. Enter the number of legs to see the compounded figure for this market's margin.
• Value in your pick (advanced): expected value per GBP 1 is your estimated chance multiplied by the odds, minus 1. Using the fair chance it comes out slightly negative (the margin); enter your own probability for an outcome to see whether the price beats your assessment.
• Market table (advanced): implied and fair chances for every outcome side by side, plus the dutching stake for each, so you can see exactly where the margin is loaded.
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