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Betting Odds Converter — Decimal, Fractional, American & Probability

Use this free tool to instantly convert between decimal odds, fractional odds, American (moneyline) odds, and implied probability. Type into any field and every other format updates automatically. Includes a payout calculator so you can see your exact return for any stake.

Odds Converter
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How to Use This Converter

Type your odds into any of the four fields — decimal, fractional, American, or implied probability — and all other formats update instantly. You don't need to select a "from" format. Click any of the three example boxes above to load common UFC odds directly into the tool.

The payout calculator lets you enter any stake and instantly see your total return and profit. The break-even win rate shows the minimum win percentage needed to profit at those odds.


The Four Odds Formats Explained

Decimal odds

The dominant format in Europe, Australia, and on betting exchanges. The number represents your total return per unit staked — profit plus your stake back. Decimal 2.50 on a $100 bet returns $250 total ($150 profit + your $100 stake).

Calculation: Stake × Decimal = Total return

$100 × 2.50 = $250 return · $150 profit

Below 2.00 = favourite. Above 2.00 = underdog. Exactly 2.00 = evens.

Fractional odds

The traditional UK and Irish format. The left number is profit, the right is stake. Unlike decimal, your stake is not included in the return figure — it's returned separately on top.

Example: 6/4 means stake $4, win $6 profit, collect $10 total.

Convert to decimal: (numerator ÷ denominator) + 1 → (6÷4) + 1 = 2.50

American (moneyline) odds

Standard on US sportsbooks — DraftKings, FanDuel, ESPN BET. Positive odds show profit on a $100 stake. Negative odds show how much you must stake to profit $100.

+150 → profit $150 on a $100 stake · total return $250

-200 → stake $200 to profit $100 · total return $300

Implied probability

The win percentage built into the odds by the sportsbook. Comparing it to your own probability assessment is how you find value bets. Both sides of any market always sum to more than 100% because of the vig.

Decimal 2.50 → 1 ÷ 2.50 × 100 = 40.0%

-110 each side → 52.4% + 52.4% = 104.8% total · vig = 4.8%


Conversion Formulas

Every calculation this tool makes uses these exact formulas.

Decimal → probability (1 ÷ decimal) × 100
e.g. 1÷2.50×100 = 40%
Fractional → decimal (num ÷ den) + 1
e.g. (3÷2) + 1 = 2.50
American (+) → decimal 1 + (american ÷ 100)
e.g. 1+(150÷100) = 2.50
American (−) → decimal 1 − (100 ÷ american)
e.g. 1−(100÷−200) = 1.50
Probability → decimal 100 ÷ probability
e.g. 100÷40 = 2.50
Decimal → American (−) −100 ÷ (decimal − 1)
e.g. −100÷(1.50−1) = −200

Odds Conversion Table

Common UFC and MMA odds across all four formats. Favourites above the evens line, underdogs below.

Fractional Decimal American Implied probability

Why Implied Probability Is the Number That Actually Matters

The format your sportsbook uses is just presentation. The number that determines whether a bet has value is the implied probability. Once you can translate any format into a percentage, you can make the only comparison that matters: does the market's implied probability match your own assessment?

If a UFC fighter is priced at +150 (40% implied) and your analysis says they win 52% of the time, you have a 12-point edge. That gap is where long-term profit lives. It is also the foundation of closing line value (CLV) — the metric that separates genuine bettors from lucky streaks.

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Every pick released through this service has been independently tracked at betMMA.tips and bettin.gs since 2016. Positive closing line value every year. Nothing deleted, nothing reset.

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Frequently Asked Questions

Decimal odds include your stake in the return. Decimal 3.00 on a $10 bet returns $30 total — $20 profit plus your $10 stake back. Fractional odds show profit only — 2/1 on a $10 bet gives $20 profit, with your $10 stake returned separately. Both describe the same bet. Decimal is simpler for calculating implied probability; fractional is the traditional UK and Irish format.

For positive American odds: decimal = 1 + (american ÷ 100). So +200 → 1 + 2.00 = 3.00.

For negative American odds: decimal = 1 − (100 ÷ american). So -150 → 1 + 0.667 = 1.667.

Because of the vig — the sportsbook's built-in margin. A typical UFC line at -110 both sides implies 52.4% + 52.4% = 104.8%. The extra 4.8% is the book's edge regardless of outcome. To profit long-term you need to consistently find bets where your assessed probability exceeds the implied probability.

Evens (1/1 fractional · 2.00 decimal · +100 American) means you profit exactly your stake if you win. A $50 bet at evens returns $100 total — $50 profit plus your $50 stake back. It implies exactly 50% probability.

Use decimal for your own analysis — it is the simplest format for working out implied probability and expected value. Most sportsbooks let you switch display formats in settings. If you use US books like DraftKings or FanDuel and see American odds, use this converter to translate them before doing your analysis.

Closing line value (CLV) measures whether you consistently get better implied probability than the final market price before an event. If you bet a fighter at +150 (40% implied) and the line closes at +120 (45.5% implied), you had positive CLV. Consistent positive CLV over hundreds of bets is the strongest evidence that a betting edge is genuine. Read the full CLV guide →


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