Odds Calculator: Convert Odds and Work Out Your Return

The odds calculator below converts a price between fractional, decimal and American formats, shows the implied probability and works out what your stake returns. Type the odds exactly as the bookmaker shows them, add a stake, and the results update as you type.

How to use the odds calculator

There are two fields to fill in and six numbers to read.

• Enter the odds in whatever format you have. Fractions take a slash (5/2, 11/8, 100/30), decimals take a point (3.50, 1.91) and American prices take a sign (+250, -200). You can also type evens.
• Enter your stake as a plain number. The tool has no currency symbol, so £10, $10 and ₹10 all go in as 10 and the results come back in the same unit.
• Read the outputs: decimal, fractional and American odds, implied probability, total return and profit.
• Change the odds to compare prices from different bookmakers on the same selection.

Two input details save confusion. A number with no sign that is 100 or higher, such as 150, is read as an American price (+150), because decimal odds that big are rare. Anything below 100 without a sign or a slash is read as decimal odds, so 2.5 means 2.50. The total return always includes your stake, and profit is the return minus the stake.

The formulas behind the odds calculator

Every result starts by turning the price into decimal odds, because a decimal price already includes the stake. The conversions are short:

• Fractional to decimal: divide the first number by the second and add 1. 5/2 becomes 2.5 + 1 = 3.50.
• American plus to decimal: divide by 100 and add 1. +250 becomes 2.5 + 1 = 3.50.
• American minus to decimal: divide 100 by the number and add 1. -200 becomes 0.5 + 1 = 1.50.
• Implied probability: 1 divided by the decimal odds. 1 / 3.50 = 0.2857, shown as 28.6%.
• Total return: stake x decimal odds.
• Profit: total return minus stake.

Going the other way, decimal odds of 2.00 or more become a plus American price: subtract 1 and multiply by 100, so 2.75 is 1.75 x 100 = +175. Below 2.00 the American price is a minus number: divide 100 by the decimal price minus 1, so 1.50 is 100 / 0.50 = -200.

Worked examples: a 5/2 shot and a -110 spread

Start with a UK price. You back a team at 5/2 with £10. The decimal price is 5 / 2 + 1 = 3.50, so the total return is £10 x 3.50 = £35 and the profit is £25. The American equivalent is +250, meaning a $100 stake wins $250. The implied probability is 1 / 3.50 = 28.6%, so the price says the team wins a little more than one time in four. If you rate the real chance higher, the price looks generous. That comparison is the whole basis of value betting.

Now a US price. A point spread at -110 is the standard line at many American sportsbooks. In decimal that is 1 + 100 / 110 = 1.909. A $110 stake returns $110 x 1.909 = $210, a profit of $100, which is where the bet-110-to-win-100 shorthand comes from. The implied probability is 1 / 1.909 = 52.4%. Both sides of a -110 spread add up to 104.8%, and the 4.8 points above 100% are the sportsbook's margin.

The fractional result for -110 is 10/11, a price UK bookmakers use too. Type 1.91 instead and the calculator shows ≈ 10/11, because 1.91 is a rounded version of the same price and does not match the fraction exactly.

What the odds calculator does not cover

The tool assumes a single bet that either wins or loses at the price you enter. These cases change what you are actually paid:

• Void bets and non-runners. If the event is cancelled or your selection does not take part, the stake is usually returned and there is no profit to work out.
• Dead heats. When selections tie, the stake is normally divided between them, so you are paid on part of it at the full price.
• Rule 4 deductions. In UK and Irish horse racing, a late withdrawal can cut the winnings on fixed-odds bets by a set amount per pound, depending on the price of the horse that came out. The calculator shows the payout before any deduction.
• Each-way bets. Place terms add a second bet at a fraction of the odds. Use the each way calculator for those.
• Exchange commission. On a betting exchange your net winnings are reduced by the commission rate, which the calculator does not subtract.
• Maximum payouts. Bookmakers limit what a single bet or customer can win, and the limit varies by operator and sport.

When the result matters, read the settlement rules of the bookmaker you use.

Related guides and a quick check before you bet

How betting odds work explains the three formats and where each one is used. The implied probability guide shows how to add up a whole market, measure the overround and strip out the margin to reach a fair price. If you are combining selections, the parlay calculator multiplies the legs for you, and the guide to parlays and accumulators covers how they settle.

Before you place the bet, run three checks. Convert the price to implied probability and compare it with your own estimate of the chance. Compare the price at more than one bookmaker, since 2.00 instead of 1.91 pays about 4.7% more on every winning bet. And size the stake from a fixed bankroll rather than from what you hope to win; our guide to bankroll management sets out simple staking plans. Betting laws differ by country and, in the US and India, by state, so check the rules where you live and use a licensed operator. If betting stops being fun, our responsible gambling page lists where to get help.