Odds calculator
Convert any price between American, decimal and fractional, read the win chance it implies, and check whether it beats your own estimate.
- American
- -110
- Decimal
- 1.909
- Fractional
- 10/11
- Implied chance
- 52.38%
- Value per $1
- +5.00%
- Kelly stake
- $55.00
The calculator is the first step.
STRATOS compares live market prices and shows where the price differs from the model's fair estimate.
Reading a price
A minus price is what you risk to win $100: -110 risks $110 for $100. A plus price is what $100 wins: +150 wins $150. Decimal odds fold the stake back in, so 2.50 returns $2.50 for every $1 including the stake.
Implied chance is simply 1 ÷ decimal. Two sides of the same market always add up to more than 100% — that gap is the sportsbook's margin, which is why shopping the best price matters more than picking winners.
Stratos compares every price across real books and keeps a public settled record. Build a parlay or see the track record.
Odds conversion table
Common American prices with their decimal and fractional equivalents, the win chance each one implies, and the profit on a $100 stake.
| American | Decimal | Fractional | Implied chance | Profit on $100 |
|---|---|---|---|---|
| -400 | 1.250 | 1/4 | 80.00% | $25.00 |
| -250 | 1.400 | 2/5 | 71.43% | $40.00 |
| -200 | 1.500 | 1/2 | 66.67% | $50.00 |
| -150 | 1.667 | 2/3 | 60.00% | $66.67 |
| -130 | 1.769 | 10/13 | 56.52% | $76.92 |
| -110 | 1.909 | 10/11 | 52.38% | $90.91 |
| +100 | 2.000 | 1/1 | 50.00% | $100.00 |
| +120 | 2.200 | 6/5 | 45.45% | $120.00 |
| +150 | 2.500 | 3/2 | 40.00% | $150.00 |
| +200 | 3.000 | 2/1 | 33.33% | $200.00 |
| +300 | 4.000 | 3/1 | 25.00% | $300.00 |
| +500 | 6.000 | 5/1 | 16.67% | $500.00 |
Worked example
A book offers +150 on a side you think wins 45% of the time. In decimal that is 2.50, an implied chance of 40%.
Your estimate is 5 points higher than the price, so the expected value is 0.45 × $150 − 0.55 × $100 = $12.50 per $100 staked, or +12.5%. On a $1,000 bankroll the full Kelly stake would be about $83 — most bettors would take a quarter of that.
Flip your estimate to 38% and the same price turns negative: 0.38 × $150 − 0.62 × $100 = −$5. The price never changed; the honesty of the estimate did.
Odds questions people ask
- How do you calculate a payout from betting odds?
- Multiply your stake by the decimal odds to get the total payout. $50 at +150 (2.50) pays $125, a $75 profit; $50 at -150 (1.667) pays $83.33, a $33.33 profit.
- How do you turn odds into a probability?
- Divide 1 by the decimal odds. +150 is 1 ÷ 2.50 = 40%; -150 is 1 ÷ 1.667 = 60%. That is the chance the price needs to break even, including the book's margin.
- What does -110 mean?
- You risk $110 to win $100. In decimal that is 1.909, and it implies a 52.38% break-even win chance — the extra 2.38% over an even bet is the sportsbook's margin.
- How do I convert American odds to decimal?
- For a plus price, divide it by 100 and add 1 (+150 becomes 2.50). For a minus price, divide 100 by the number and add 1 (-150 becomes 1.667).
- What is implied probability?
- One divided by the decimal price, shown as a percentage. It is how often the bet must win just to break even, margin included.
- Why do both sides add up to more than 100%?
- That overround is the book's built-in margin. Two -110 sides imply 52.38% each, or 104.76% together — the 4.76% is the house edge on that market.
- What is expected value on a bet?
- Your estimated win chance multiplied by the profit, minus the chance of losing multiplied by the stake. Positive means the price is better than your estimate; negative means it is worse.
- Should I bet the full Kelly stake?
- Most bettors use a half or quarter of it. Full Kelly assumes your probability estimate is exactly right, and a small error there produces a very large swing in bankroll.
See which book has the best price
Converting a price is the easy half. Stratos compares the same market across live sportsbooks, shows the fair price behind it, and grades every published pick in public.