How to Convert Betting Odds in 2026: American, Decimal, Fractional and Percentage Prices

The quick answer

• American to decimal: for positive odds, 1 + odds / 100. For negative odds, 1 + 100 / the odds without the minus sign. +150 is 2.50 and -150 is 1.6667.

• Decimal to fractional: subtract 1 and write what's left as a fraction. 2.50 becomes 3/2.

• Implied probability: 1 divided by the decimal odds. 2.50 is 40%.

• Prediction-market price: a 40c contract pays $1 if it wins, so the price is the implied probability and the decimal odds are 1 / 0.40 = 2.50. On a Novig pre-game straight there's no fee to add, so that price is the whole cost.

• Percentage to American: above 50%, -100 x p / (1 - p). Below 50%, +100 x (1 - p) / p.

• Profit vs payout: profit is stake x (decimal - 1), and payout adds the stake back. $50 at +150 profits $75 and pays out $125.

The four formats describe the same price in different units. It's easiest to start with decimal, since every other format converts to and from it in one step and it already includes the stake.

What each format means

American odds are written around $100. A plus number is the profit on a $100 stake, so +150 wins $150. A minus number is what you stake to win $100, so -150 risks $150 to win $100.

Decimal odds are the total return per $1 staked, stake included. At 2.50, $1 comes back as $2.50.

Fractional odds are profit over stake. At 3/2 you win $3 for every $2 staked, and 1/1 is even money, usually written "evens."

Prediction markets quote prices in cents or percentages. Kalshi's guide to reading its prices says "A 'Yes' contract pays $1 if the event happens and $0 otherwise," and "A 'Yes' price of p cents implies a market-implied probability of about p% that the event will happen." Novig shows the same thing as a percentage. Its odds calculator says "odds are shown as percentages: the market's implied probability that an outcome happens," and gives the payout rule: "Divide your stake by the percentage: $100 at 40% returns $250."

How we checked

The formulas are standard odds arithmetic, and every figure below was computed exactly and rounded only at the end. We checked them against the reference table in Novig's odds calculator, which lists +200 at 33.3% and 3.00, +100 at 50% and 2.00, -110 at 52.4% and 1.91, -150 at 60% and 1.67, and -200 at 66.7% and 1.50. All five match. Kalshi's description of its contracts comes from its March 2026 guide to reading probabilities and Novig's fees from its fee schedule, all opened on 7 October 2026.

The conversion formulas

American to decimal: Positive odds: decimal = 1 + American / 100. +110 is 2.10. Negative odds: decimal = 1 + 100 / |American|. -110 is 1 + 100 / 110 = 1.9091.

Decimal to American: Decimal of 2.00 or more: American = (decimal - 1) x 100. 2.10 is +110. Decimal under 2.00: American = -100 / (decimal - 1). 1.80 is -125.

Fractional to decimal: decimal = fraction + 1. 7/4 is 2.75.

Decimal to fractional: fraction = decimal - 1, reduced. 1.6667 is 2/3.

Any format to implied probability: convert to decimal, then take 1 / decimal. 7/4 is 1 / 2.75 = 36.36%.

Percentage or cents to the other formats: decimal = 1 / p. A 62% price is 1 / 0.62 = 1.6129 decimal, and -100 x 0.62 / 0.38 = -163.16, which rounds to -163. A 35% price is +100 x 0.65 / 0.35 = +185.71, about +186.

Conversion table for common prices

Profit and payout are on a $100 stake. The implied probability column is also the prediction-market price, in cents, for the same odds.

Each payout is the profit plus the $100 stake, and each implied probability is 1 divided by the decimal in the same row.

Profit vs total payout

Decimal odds quote the payout, while American and fractional odds quote the profit.

$50 at -150 makes a profit of 50 x 2/3 = $33.33 and a payout of $83.33. The same $50 at +150 makes $75 in profit and pays out $125.

On Novig, $50 at 40% returns 50 / 0.40 = $125, the same payout as +150, because 40% and +150 are the same price. Kalshi's guide gives the cents version: a 25c price is a 25% probability and 3-to-1 odds, and 3/1 is +300 in the table.

Implied probability and the margin

Implied probability is the chance a price implies, margin included, and a sportsbook prices both sides above fair value. At -110 on each side, each implies 52.38% and the two add to 104.76%; the extra 4.76 points is the book's margin.

A prediction market's two prices can also add to a bit more than 100% when you take the best available price on each side. That gap is the difference between what two users will pay. Novig's fee schedule states "There's no vig or juice built into our prices," and charges no fee on pre-game straight trades for either side.

Novig's live straight taker fee is 0.03 x price x (1 - price) per contract, which is $0.75 on 100 contracts at 50%. Those 100 contracts cost $50.75 all in and pay $100, so the effective decimal is 1.9704 and the effective implied probability is 50.75%.

Common conversion mistakes

-110 converts to 1.9091 in decimal; a price of 1.10 decimal is a -1000 favorite.

Novig's reference table rounds -110 to 1.91, which doesn't matter for reading a price, but at $1,000 the exact 1.9091 pays $1,909.09, against $1,910 at the rounded price.

A 25c contract pays $1 if it wins, so it profits 75c on a 25c cost.

A fraction below evens is a favorite: 1/3 is -300 in American odds, and 3/1 is the underdog at +300.

What to look for

• Format: convert everything to decimal first, then to whatever format you need.

• Payout vs profit: decimal includes the stake; American and fractional don't.

• Rounding: keep four decimal places until the final number.

• Margin: add the implied probabilities of every side; anything above 100% is margin or spread.

• Fees: on a venue that charges per contract, convert the all-in cost with the fee included. Where no fee applies, the quoted price is already the all-in cost.

Odds conversion FAQ

How do you convert American odds to decimal?

For positive odds, divide by 100 and add 1, so +150 is 2.50. For negative odds, divide 100 by the number without the minus sign and add 1, so -150 is 1.6667.

How do you convert odds to implied probability?

Divide 1 by the decimal odds. 2.50 is 40%, and -110 (1.9091) is 52.38%.

What is -110 as a percentage?

52.38%. Two sides at -110 add to 104.76%, and the 4.76 points above 100% are the book's margin.

What do 60% odds mean in American odds?

60% is -150 in American odds, 1.6667 in decimal and 2/3 in fractional. A $100 stake profits $66.67 and pays out $166.67.

Is +200 the same as 2/1?

Yes. Both are 3.00 in decimal and imply 33.33%, so $100 profits $200 and pays out $300.

How do prediction markets show odds?

As a price per $1 contract, which is also the implied probability. Kalshi quotes in cents, so a 25c price is 25%. Novig quotes percentages, and a winning bet returns the stake divided by the percentage, so $100 at 40% returns $250.

Sources

All opened 7 October 2026.

Novig odds calculator and conversion table: tools.novig.com/odds-calculator

Novig fee schedule: support.novig.com/en/articles/16195057-fees-on-novig

Kalshi News, "How to translate Kalshi market prices into real-world odds and probabilities," 12 March 2026: news.kalshi.com/p/how-to-read-probabilities