Betting variance is how far your real results swing away from what your bets are worth. Even with a genuine 5% edge at odds of 3.0, £10 bets expect £500 profit over 1,000 bets, but the result could land anywhere from about -£387 to £1,387. Short runs of results say little about whether you're good.
What variance in betting means
Every bet has an expected value: what it's worth on average if you could place it thousands of times. Your results don't follow that average closely. They wander above and below it, sometimes for a long time. That wandering is variance.
Variance is why a punter with an edge can lose for months, and why someone with no edge can be well up after a lucky few weeks. It doesn't go away. It only gets smaller compared with your total profit as you place more bets.
Why longer odds mean bigger swings
At odds of 2.0 you win about half your bets, so results even out quickly. At 6.0 you win about one in six, and long losing runs are normal. The same edge takes far longer to show up at bigger prices.
| Odds | 100 bets | 500 bets | 1,000 bets | 5,000 bets |
|---|---|---|---|---|
| 2.0 | 31% | 13% | 6% | 0% |
| 3.0 | 36% | 22% | 13% | 1% |
| 6.0 | 41% | 31% | 24% | 6% |
Even after 1,000 bets at 6.0, a punter with a real 5% edge has about a one in four chance of being down. That's what normal looks like at those odds.
The likely range after 1,000 bets with a 5% edge
| Odds | Expected profit | Likely range |
|---|---|---|
| 2.0 | £500 | -£119 to £1,119 |
| 3.0 | £500 | -£387 to £1,387 |
| 6.0 | £500 | -£913 to £1,913 |
The expected profit is the same £500 in every row, because the edge and the total staked are the same. The range is what changes. At bigger odds you could easily finish well down or well up.
Try your own odds, stakes and edge with the betting variance calculator, and watch twenty random runs play out.Variance calculator →How many bets it takes to prove an edge
To be fairly confident a profit isn't luck, you need enough bets for your edge to stand clear of the swings. The table below shows roughly how many level stake bets you need, at about 95% confidence.
| Odds | 3% yield | 5% yield | 10% yield |
|---|---|---|---|
| 2.0 | 4,445 | 1,600 | 400 |
| 3.0 | 8,889 | 3,200 | 800 |
| 6.0 | 22,223 | 8,000 | 2,000 |
A tipster with 200 tips at an average of 4.0 and a 10% yield hasn't proved anything yet. The same yield over 2,000 tips at 2.0 is much stronger evidence.
Four ways to live with betting variance
- Keep stakes small compared with your bankroll, so a normal losing run can't finish you.
- Stake the same amount, or a fixed share of your bank, instead of chasing losses.
- Judge your bets by the price you got, not the result. Closing line value shows skill much sooner than profit does.
- Judge tipsters and value betting tools on thousands of bets, not one good or bad month.
Calculators for staking and edge:Variance calculatorKelly criterion calculatorOdds converter
Value betting tools and tipsters we've reviewed
Questions people ask
What is variance in betting?
Variance in betting is how far your results stray from what your bets are worth on average. It's why good bets lose and bad bets win in the short run.
How long can a losing run last with an edge?
Much longer than most people expect, especially at bigger odds. With a 5% edge at 6.0, about one in four punters is still down after 1,000 bets.
Does variance go away over time?
Not completely. The swings in pounds keep growing, but more slowly than your expected profit, so over enough bets the edge stands out.
How many bets does it take to be profitable?
It depends on your odds and yield. To be fairly confident a profit isn't luck, you need roughly 1,600 level stake bets at 2.0 with a 5% yield, 3,200 at 3.0 and 8,000 at 6.0.
How do I reduce variance?
Bet at shorter odds, keep stakes level and small compared with your bankroll, and place more bets, so your edge stands out more clearly from the swings. Matched betting removes most variance because the result doesn't matter.