Sports Betting Odds Explained: Fractional, Decimal, and Moneyline

You open a sportsbook and see -110, 2.00, and 5/2 on the same game. They look simple, yet they hide real math and real cost. In a few minutes, you will read any odds format, switch between them, and see the true chance behind each price. If you want a short base first, the American Gaming Association has a clear primer on sports betting basics.

Quick cheat sheet (read this first)

Here is a fast table you can use right away. It shows what each odds line means in plain words, the implied chance, profit on a fixed $100 stake, and the closest match in other formats. Note: “profit” is what you win; “total return” is stake plus profit. For math ideas in plain language, see Britannica on probability.

Note on the table: “Profit on $100 stake” is set to the same $100 for easy compare. For American odds, books often quote profit on $100 or stake for $100 profit; here we fix the stake at $100 so you can scan fast.

Moneyline odds: favorites and underdogs, in dollars

Moneyline (also called American odds) show a plus or a minus. A minus means the team is a favorite. A plus means an underdog.

• -150: you need to risk $150 to profit $100. If you stake $100 instead, profit is $66.67.
• +200: you risk $100 to profit $200. If you stake $37, profit is $74. If you stake $250, profit is $500.

To find chance from a moneyline without a tool, use these quick forms:
For a minus price: chance = odds / (odds + 100). Example -150 → 150 / 250 = 0.60 → 60%.
For a plus price: chance = 100 / (odds + 100). Example +200 → 100 / 300 = 0.333 → 33.3%.

If you want a deeper read on the math and what books “imply” with a price, see Investopedia’s guide to implied probability.

Decimal odds: clean and fast for mental math

Decimal odds show total return. 2.40 means $1 becomes $2.40 total (so profit is $1.40). Many bettors like decimals because the chance is just 1 / odds.

• 1.80 → chance ≈ 1 / 1.80 = 0.556 = 55.6%.
• 2.40 → chance ≈ 1 / 2.40 = 0.417 = 41.7%.
• 3.75 → chance ≈ 1 / 3.75 = 0.267 = 26.7%.

If you need a short refresh on ratios and percents, The Open University has a clear note on percentages and ratios.

Fractional odds: 5/2, 10/11, and “Evens”

Fractional odds show profit relative to stake. The first number is profit, the second is stake. So 5/2 means profit $5 per $2 stake. Your total return is stake + profit.

• 5/2 → profit $250 on $100 stake; return $350; chance ≈ 1 / (1 + 5/2) = 1 / 3.5 = 28.6%.
• 10/11 → common spread price; very close to -110 and decimal 1.91.
• 1/1 → “Evens.” Profit equals stake. Decimal 2.00. American +100.

Not sure what “evens” means in sports talk? The BBC has a simple explainer on evens explained.

Convert odds without a calculator

Here are the core swaps you will use most. Keep them close. After two or three tries, you will do them in your head.

• Moneyline to Decimal: If plus: D = 1 + (ML / 100). Example +140 → 1 + 1.40 = 2.40. If minus: D = 1 + (100 / |ML|). Example -125 → 1 + (100/125) = 1.80.
• Decimal to Moneyline: If D ≥ 2.00: ML = (D − 1) × 100. Example 2.40 → +140. If D < 2.00: ML = −100 / (D − 1). Example 1.80 → −100 / 0.80 = −125.
• Fractional to Decimal: D = (A/B) + 1. Example 7/5 → 1.4 + 1 = 2.4.
• Decimal to Fractional: F = D − 1, then write as a simple ratio. Example 1.91 → 0.91 ≈ 10/11.

One more core idea is value. Price is not the same as chance. A short read on expected value helps you test if a price is fair for your view.

Implied probability and the bookmaker’s margin (vig/overround)

Implied probability is the chance that matches a price. In a fair world, all outcomes in one market would add to 100%. But a book adds a fee inside the prices. This fee is called vig, margin, or overround.

Example, a 1X2 soccer line:

• Home 1.80 → chance 1/1.80 = 55.56%.
• Draw 3.50 → chance 1/3.50 = 28.57%.
• Away 4.60 → chance 1/4.60 = 21.74%.

Sum = 55.56 + 28.57 + 21.74 = 105.87%. The extra 5.87% is the book’s margin on that market. This is the “tax” you pay to bet. You can read more on the math and term in the overround article. For an industry view and historical data on hold and margins, see UNLV’s Center for gaming research.

Odds in context: spreads, totals, and line moves

Why is -110 so common on spreads and totals? It often splits the fee between sides. You pay about 4.5% to 5% in the long run if you flip coins at -110. On some books or sports it can be -108, -112, or other small steps. Half-points (like -3.5) stop ties and push outcomes to a side.

Lines move. They move when news hits, when sharp money comes in, or when the book balances risk. “Closing line value” (CLV) is how your price compares to the final price before the game. If you beat the close often, you most likely bet into good numbers. For a data angle, the Harvard Sports Analysis Collective has a post on closing line value.

Where each odds format shows up

Moneyline odds are standard in the U.S. and Canada. Decimal odds rule in Europe, Australia, and most of the world. Fractional odds are still a big thing in the U.K. and on horse racing cards. Most apps let you switch formats in Settings. In the U.K., the regulator has useful public guides on betting in Great Britain.

Common mistakes to avoid

• Mixing profit with total return. Decimal shows return; fractional shows profit; moneyline is mixed. Always check if the number is profit or return.
• Wrong chance math. A fast fix: decimal chance is 1/odds. Moneyline needs the short forms above. Write it down once, then it sticks.
• Forgetting the vig. Two sides at -110 are not even. The gap is the fee.
• Chasing “boosts” without limits in mind. Many boosts have low max stake or cover only part of the fee.
• Betting a number, not a price. The team may win, yet a bad price can kill long-run results.

If you want a short piece on how our brains read chance (and how to do better), this FiveThirtyEight article on thinking about probabilities is a nice start.

Tools, habits, and responsible play

Use a simple routine:

• Keep an odds cheat sheet close (like the table above).
• Log your bets. Note stake, price, line time, and closing line.
• Compare prices across books before you bet. A tiny edge each time adds up.
• Read house rules. Know how pushes, voids, and tie-breakers work.

Editor’s note: we test and compare odds displays, fees, and settings across many sportsbooks. If you like clean side‑by‑side format checks and clear pricing notes, you can browse independent reviews and tools at bestecasinoer.biz.

Please play within your budget. If betting stops being fun, pause and speak with someone you trust. In the U.S., you can get help. In the U.K., see safer gambling advice and support services.

Myth vs fact (short and direct)

• Myth: Decimal and American odds pay differently. Fact: Payout is the same at true equal prices; only the format changes.
• Myth: Boosted odds always mean profit. Fact: Some boosts are small, capped, or offset by rules. Check stake limits and true chance.
• Myth: A good team at any price is fine. Fact: Price matters more than the team. Long-term gain comes from numbers, not names.

FAQ

Which odds format is easiest to learn?

Decimal is the simplest for most people. One step: chance ≈ 1 / odds. Profit is (odds − 1) × stake. Still, learn moneyline too if you bet U.S. markets.

How do I convert -150 to decimal and to fractional?

Decimal: 1 + (100 / 150) = 1.67. Fractional: 0.67 profit per 1 stake → about 4/6 (often shown that way in books). American -150, Decimal 1.67, Fractional 4/6 are the same price.

Why are so many spreads priced at -110?

It bakes in the book’s fee and keeps sides balanced. At -110, you need 52.38% hit rate just to break even. Some books shift to -108 or -112 based on market flow.

What’s the difference between profit and return?

Profit is what you win on top of your stake. Return is stake plus profit. Decimal odds show return. Fractional shows profit. Moneyline is mixed and needs a quick check.

How do I estimate implied probability from decimal odds quickly?

Use chance ≈ 1 / odds. Example 2.50 → 1/2.50 = 40%. That is fast and good enough for most use.

Are boosted odds always better?

No. Many boosts have small limits or special rules. Compare the new price to the market and check if the boost beats the fee by a fair margin.

Sources, method, and update notes

Formulas used: moneyline chance (minus) = odds/(odds+100); (plus) = 100/(odds+100). Decimal chance = 1/odds. Fractional to decimal = (A/B)+1. We checked math with hand tests and cross‑read with public guides. Numbers round to two decimals or to neat fractions where common in markets. We update when format options or house rules change in major apps. Last updated: 2026-02-16.

About the author

Our editor has hands‑on work with odds models, pricing checks, and line move tracking across U.S. and EU books. We test examples with real market snapshots and re‑run the math before each update. A second editor reviews the numbers and language for clarity.

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