Calculate the figures
Illustrative mathematics only. Values do not predict outcomes or guarantee a return.
Three odds formats express one underlying price
Decimal odds express gross return per unit staked, fractional odds represent potential net profit relative to the stake and American odds express a net profit per 100 staked or the stake necessary to win 100. Correct conversions should produce equivalent returns before rounding. In this calculator, the user chooses a format, enters a valid price and optionally provides a positive stake. The results display equivalent price formats, implied break-even probability and potential single-bet returns.
Decimal, fractional and American conversion formulas
For fractional a/b, decimal odds equal 1 + a/b, with positive a and b. For positive American +A, decimal odds equal 1 + A/100. For negative American −A, with A as the positive magnitude, decimal odds equal 1 + 100/A. The inverse American conversion for decimal d ≥ 2 is +(d−1)×100; for 1 < d < 2 it is −100/(d−1). Equivalent displayed fractional values can be approximate when the decimal price is not an exact small-ratio fraction.
Convert a common odds example
Decimal 2.50 corresponds to fractional 3/2 and American +150. Each implies a break-even probability of 1/2.50 = 40 percent. With a 20-unit stake, the gross return on a winning selection is 50 units, including the original stake; net profit is 30 units. If the selection loses, the stake is lost. This calculation does not estimate actual probability and cannot make an outcome more likely.
Use implied probability cautiously
Implied probability is a transformation of the listed price: 100 divided by decimal odds. It is useful as a break-even threshold under the simplified one-bet model, but the bookmaker margin and true uncertainty are not separately identified. For a two-outcome market with prices 1.90 and 1.90, the implied probabilities total about 105.26 percent. Avoid claiming the arithmetic implied probability is the objectively correct forecast of either outcome.
What the tool does not calculate
A single-price converter does not remove overround, model outcome probabilities or account automatically for tax, fees, promotions, boosts, partial settlement, refunds, cash-out offers or dead heats. These factors require separate case-specific rules. Fractional approximations are rounded for readability, while the internal decimal value is retained for the payout calculation. Read the original market settlement conditions before treating the result as a final payment expectation.
Validation and accessibility rules
Decimal odds must exceed 1.00. Fractional odds must be entered as positive numerator and denominator separated by a slash. American odds must be positive or negative with magnitude at least 100; pick’em and specialty prices need their own clearly stated convention. The form reports errors without silently converting invalid inputs, updates a live result region and leaves all calculations on the visitor’s device.
Compare a selection before risking money
To assess a possible wager, compare the quoted price with a defensible independent probability estimate and a predetermined entertainment budget. Use the expected value calculator if you already have a probability model; do not treat a decimal-to-percentage conversion as a prediction. If betting becomes financially or emotionally difficult, stop and seek independent support rather than trying to use a calculator to recover losses.
Read a converted price in context
Two sportsbooks may display equivalent odds using different conventions, so converting to one standard can help compare their offers. Yet prices are time-sensitive and can change before a bet is accepted. Wager conditions, maximum stakes, boost eligibility and settlement rules can also vary. Conversion is useful for translation, not for determining whether an operator is appropriate for a particular country or whether a promotional claim is accurate. If prices differ across markets, check that the selections represent the same outcome, timing, and rules before treating them as a comparable pair.
How rounding changes displayed fractions
The exact decimal representation of some quoted fractional prices involves many digits. The converter searches for a readable approximate numerator and denominator and labels approximations when needed. Display rounding may make one output differ by a small amount from a hand calculation using a shortened price, but the gross and net payouts use the full internal decimal conversion. This also explains why adding displayed implied percentages for several outcomes may show a slight rounding discrepancy. The tool does not fetch live odds and cannot verify whether any price is still available.
Verify payout arithmetic independently
A straightforward check is to multiply the decimal odds by the original stake and subtract the stake for net profit. For a price of 1.80 and a stake of 25 units, gross return would be 45 units and net profit 20 units if the selection wins. Compare that output with a fraction of 4/5 and American -125. The stake is included in gross return but not in net profit. Keeping those terms separate avoids exaggerating the potential gain described in promotional materials and comparison articles.
Related guides and responsible gambling
For additional explanations, read the odds and probability guide, value betting guide, sports betting strategies, and responsible gambling information. Independent support is available from the National Council on Problem Gambling. Promotional links on this site refer to Shuffle, not bet365.