How tennis prices work: why 62¢ means a 62% chance

A price of 62¢ means the market thinks that player has about a 62% chance of winning. That's because each share pays $1 if they win and nothing if they lose, so a fair price is the chance of winning times $1. As the match goes on, that chance changes with every point, and so does the price.

The $1 rule

Everything starts with one fact: a winning share pays $1. Imagine the same match could be played 100 times. If Player A wins 62 of them, a share in A pays $1 in 62 matches and nothing in the other 38. On average it's worth 62¢ a match. That's the fair price.

If you pay less than the true chance, you've got a good deal. If you pay more, you've overpaid. The hard part is that nobody knows the true chance. The price is the market's best guess.

Why the two prices add up to about $1

Exactly one player wins, so between them the two shares always pay out $1. That's why A at 62¢ means B is near 38¢.

In practice they rarely add up to exactly 100¢. Each player has a price to buy at (the ask) and a slightly lower price to sell at (the bid). Add the two buy prices together and you might get 101¢ or 102¢. That gap is the spread, and it's what you pay for being able to trade straight away. On busy matches it's often 1¢. On a quiet Challenger match it can be several cents.

Price, probability and odds

If you're used to bookmaker odds, the price is the same information written another way. Here's how a few prices convert:

To go from price to decimal odds, divide 1 by the price in dollars: 1 ÷ 0.62 = 1.61. To go back, divide 1 by the decimal odds. The free odds converter does all of these for you, including fractional and American odds.

One difference is worth knowing. A bookmaker builds a margin into their odds, so their implied chances for both players add up to more than 100%, sometimes 105% or more. On a busy prediction market the two prices usually add up much closer to 100%, so the price is a cleaner read of what people think. You still pay to trade, though, through the spread and, on Polymarket, a fee on orders that fill straight away. Check their fee page for the current rates.

How the price moves point by point

Here's where tennis gets interesting. The scoring system means some points barely matter and others matter a lot.

To show this, I ran a simple point-by-point model of a close men's match on a hard court. Both players win about 64% of points on their own serve, which means they each hold serve roughly 80% of the time. The table follows Player A's price through one service game at 4-4 in the first set.

A few things stand out. The first point of the game moves the price by only 2¢. Going down 15-30 costs 5¢, because a break is now a real threat. And the difference between holding and being broken is 25¢ for that one game. That's why traders watch break points so closely.

Real prices follow the same pattern, but they're noisier. People react to how the players look, not just the score, and the market can overreact or underreact. More on that in why the price jumps on a break of serve.

Which points matter most

• Break points. Win one and the returner takes a big step towards the set.
• Set points and tiebreaks. A tiebreak decides a whole set in a handful of points, so each point swings the price hard.
• The deciding set. A break in the final set is worth far more than the same break in the first. In my model, a break at 2-2 in the final set of that close match moved the leader from 53¢ to 82¢, against 55¢ to 69¢ in the first set.
• Points on serve. Losing a point on your own serve hurts more than losing one on return, because you're expected to win your service games.

What the price can't see

The price is a crowd's estimate, not the truth. It can be wrong, and it can be slow. Some common reasons:

• Injuries. A player struggling with a knee might not show it in the score for a few games.
• Delays. Scores reach different people at different speeds. On the 77 Tennis board, prices and scores refresh about every 18 seconds, so a quick point can come and go before you see it.
• Thin trading. On small matches with few traders, one big order can push the price away from where it should be.
• Big names. Famous players can attract money because people like them, not because the numbers say so.

None of this makes the price easy to beat. Most of the time it's a decent estimate. But it explains why the price sometimes jumps when nothing seems to have happened.

Using this when you trade

When you look at a price, turn it into a question: "Do I think A wins more than 62% of the time from here?" If yes, buying makes sense. If you're not sure, the honest answer is to leave it. You don't have to trade every match.

The 77 Tennis board shows each player's price next to the score, with a chart of how it's moved since the start, so you can watch this happen live. It's a good way to get a feel for how much each point is worth. If you're just starting out, the beginner's guide puts all of this in context.

FAQ

Why don't the two prices add up to exactly 100¢?

Because each side has a buy price and a slightly lower sell price. The gap between them is the spread. On busy matches it's usually small, about 1¢, and on quiet ones it can be bigger.

Is the price always right?

No. It's the market's best guess, and it can be wrong or slow, especially on small matches or when a player is hiding an injury. Over many matches it tends to be a fair estimate, which is why it's hard to beat.

Why did the price move when no point was played?

Usually because of something the score doesn't show: a medical timeout, a player looking hurt, rain, or a big order on a quiet market. Sometimes it's because the scores you're seeing are a few seconds behind.

What does a price of 99¢ mean?

The market thinks the player is almost certain to win, for example at match point with a big lead. Buying at 99¢ risks 99¢ to make 1¢, so a single upset wipes out the profit from about 99 wins.

How do I convert a price to decimal odds?

Divide 1 by the price in dollars, so 62¢ is 1 ÷ 0.62 = 1.61. The odds converter also does fractional and American odds.