How to read tennis betting odds
Odds are just a probability in disguise, plus the bookmaker's cut. Once you can convert between the two, the whole board reads differently.
Decimal odds in one line
In decimal format, the number is your total return per unit staked, stake included. At @2.00, a winning 10€ bet returns 20€ (your 10€ back plus 10€ profit). At @1.50, it returns 15€. At @3.40, 34€.
Higher odds mean a bigger payout — and a lower chance the bookmaker thinks it will happen.
Odds are a probability in disguise
Every price contains an implied probability: just divide 1 by the odds.
- @1.50 → 1 / 1.50 = 66.7%
- @2.00 → 1 / 2.00 = 50%
- @3.40 → 1 / 3.40 = 29.4%
So a favorite at @1.30 is the market saying "about 77% likely", and a @4.00 underdog is "about 25% likely". Reading the board as percentages is the single most useful habit you can build.
Favorite and underdog
The lower the odds, the higher the implied probability, and the shorter the payout — that is the favorite. The higher the odds, the longer the payout and the lower the chance — the underdog. Neither label tells you who will win a single match; it only tells you what the market expects on average.
Why the two sides add up to more than 100%
Take a match priced @1.90 / @1.90. The implied probabilities are 52.6% and 52.6% — a total of 105.2%, not 100%. That extra 5.2% is the bookmaker's margin (the vig or overround), built into the prices.
It is the reason the odds are always a little shorter than the "true" chance, and why beating them over time is genuinely hard. The fair-odds guide unpacks the margin in detail.
Turning odds back into a read
Once a price is a percentage, you can compare it against an independent estimate — say, a model's probability for the same player. If the model says 60% and the market implies 51%, the model sees more chance than the price does. Whether that gap is real value or just noise is the subject of the expected value guide.
Baseline shows the implied probability alongside the model's own read on every match in Analyze.
Frequently asked questions
What does @1.80 mean in tennis betting?
A winning bet at decimal odds of 1.80 returns 1.8× your stake including the stake — a 10€ bet returns 18€. It implies about a 55.6% chance (1 / 1.80).
How do I convert odds to a percentage?
Divide 1 by the decimal odds. @2.50 → 1 / 2.50 = 40%. That is the market's implied probability for that outcome.
Why do the implied probabilities add up to more than 100%?
The extra above 100% is the bookmaker's margin (the vig or overround). It is baked into the prices and is how the book makes money regardless of the result.
Are decimal and fractional odds different?
They express the same thing differently. Decimal 2.00 equals fractional 1/1 (even money). Decimal is easier for converting to probabilities, which is why most models and analysts use it.