Odds are not just a multiplier for your stake. They are the bookmaker telling you, quite precisely, how likely they think something is. Once you can read that, every slip looks different, and some of them look a lot scarier.
This guide shows you how to turn odds into a win chance in your head, why accumulators shrink your chances faster than intuition says, and how Convat's Slip Analysis does it for every slip you convert.
Odds to win chance: the one formula you need
For decimal odds, the implied probability is:
win chance = 1 ÷ odds
| Odds | Implied win chance | Roughly |
|---|---|---|
| 1.25 | 80% | 4 times in 5 |
| 1.50 | 66.7% | 2 times in 3 |
| 2.00 | 50% | a coin flip |
| 3.00 | 33.3% | 1 time in 3 |
| 5.00 | 20% | 1 time in 5 |
| 10.00 | 10% | 1 time in 10 |
That is the bookmaker's view, slightly flattered in their favour, which brings us to the margin.
The bookmaker's margin, in one example
Add up the implied chances of every outcome in a market and you get more than 100%. Take a match priced 1.90 home, 3.40 draw, 4.20 away:
- Home: 1 ÷ 1.90 = 52.6%
- Draw: 1 ÷ 3.40 = 29.4%
- Away: 1 ÷ 4.20 = 23.8%
Total: 105.8%. The extra 5.8% is the bookmaker's margin. It means the true chance of each outcome is a bit lower than the odds suggest. On a single bet that is small. On an accumulator, it compounds on every leg.
How accumulator odds and chances multiply
An accumulator's total odds are every leg's odds multiplied together. Its win chance is every leg's win chance multiplied together. Here is a six-leg slip:
| Leg | Odds | Win chance | Band |
|---|---|---|---|
| Strong home favourite | 1.35 | 74.1% | Strong favourite |
| Over 1.5 goals | 1.50 | 66.7% | Favourite |
| Double chance | 1.65 | 60.6% | Favourite |
| Both teams to score | 1.90 | 52.6% | Even call |
| Away win | 2.10 | 47.6% | Even call |
| Underdog to win | 4.50 | 22.2% | Long shot |
| Slip | 60.0 | 1.67% | Long shot |
Five of the six legs are better than a coin flip. The slip as a whole lands about once in sixty tries. That gap between "every pick looks likely" and "the slip almost never lands" is why accumulators feel so cruel.
Find the leg carrying the risk
Look at what happens when you take legs off the bottom of that slip:
- All six legs: 60.0 odds, 1.67% win chance.
- Drop the 4.50 underdog: 13.3 odds, 7.5% win chance, about four and a half times more likely.
- Also drop the 2.10 away win: 6.35 odds, 15.75% win chance.
One long shot was doing most of the damage. Spotting that leg is the single most useful thing you can do with any slip, and it is exactly what Slip Analysis points out.
How Convat's Slip Analysis grades a slip
After every conversion, tap Slip analysis on the result. It works from the odds on your slip and shows:
Every leg, with its band
| Band | Odds |
|---|---|
| Strong favourite | under 1.40 |
| Favourite | 1.40 to 1.79 |
| Even call | 1.80 to 2.49 |
| Underdog | 2.50 to 3.99 |
| Long shot | 4.00 and above |
A combined win chance and a verdict
| Verdict | Combined win chance |
|---|---|
| Strong slip | 25% or more |
| Balanced slip | 10% to 25% |
| High risk | 3% to 10% |
| Long shot | under 3% |
A one-line summary
For example: "6-leg accumulator with a 1.67% chance of landing in full. 1 long-shot leg carries most of the risk, balanced by 3 favourites." Plain English, so you know what you are holding before you stake.
What to do with the verdict
- Long shot or high risk and you did not mean it? Drop the long-shot legs, or use Optimize Slip to rebuild to a target.
- Too many legs? Split the slip into balanced smaller tickets.
- Happy with a long shot for fun? Fine. Just stake it like a long shot.
Implied probability is the bookmaker's estimate, not a guarantee, and it already includes their margin. Nothing here makes a bet safe. It makes the risk visible, which is the first step to staying in control. See our responsible use page for more.
Frequently asked questions
How do I calculate the probability from betting odds?
Divide 1 by the decimal odds. Odds of 2.00 imply a 50% chance, 4.00 implies 25%, and 1.50 implies about 66.7%.
How do I calculate the win chance of an accumulator?
Multiply the win chances of every leg together. That is the same as dividing 1 by the slip's total odds, so a 20-odds accumulator implies about a 5% chance.
What is the bookmaker's margin?
It is how far the implied chances of every outcome in a market add up to more than 100%. A match priced 1.90, 3.40 and 4.20 adds up to about 105.8%, a margin of 5.8%.
What does Slip Analysis show?
Every leg's implied win chance and risk band, the slip's combined win chance, a verdict from Strong slip to Long shot, and a short summary of which legs carry the risk.
Why does my accumulator lose when every pick looked likely?
Because chances multiply. Six legs that each win 60% of the time land together less than 5% of the time.
Is Slip Analysis free?
Slip Analysis is a Pro feature, included in the Weekly and Monthly plans. The formulas in this guide work on any slip, by hand, for free.
