More than most people think. Over 100 bets, a win rate has a margin of error of about ±9.8 points; at 1,000 bets it's still about ±3.1. A bettor with no edge at -110 has a 27% chance of winning 55% or more of 100 bets by luck alone, and a 5% chance even over 1,000. Track closing line value to get a faster read.
Key points
- Your break-even at -110 is 52.4%; a good bettor might be at 54–56%. The gap is tiny compared with the noise.
- Distinguishing a 55% bettor from break-even takes on the order of 1,000+ bets.
- Closing line value has far less noise and says more after fewer bets.
Margin of error by sample size
A win rate measured over n bets has a 95% margin of error of roughly ±1.96 × √(0.25 ÷ n):
| Bets | 95% margin of error |
|---|---|
| 100 | ±9.8 points |
| 250 | ±6.2 |
| 500 | ±4.4 |
| 1,000 | ±3.1 |
| 2,500 | ±2.0 |
How often luck fools you
Two bettors at -110: one is exactly break-even (52.4%), one is genuinely good (55%). How often does each look like the other?
| Bets | Break-even bettor shows 55%+ | 55% bettor shows a loss |
|---|---|---|
| 100 | 26.7% | 30.7% |
| 250 | 20.4% | 18.7% |
| 500 | 13.0% | 11.3% |
| 1,000 | 5.2% | 4.6% |
After a full NFL season of betting every game, you still can't be sure which one you are.
Getting a faster answer
- Closing line value. Whether the market moved toward your bets is a much less noisy signal than wins and losses. See CLV explained.
- Units, not wins. Underdog bettors can win under 50% and still profit; count profit in units.
- Separate your bet types. Parlays and props have much more variance than straight bets and can hide a good or bad record.
A real example
FakeBet's Crowd Report tracks the side most players backed in each game. In September 2026 the crowd went 49–46, which is 51.6% over 95 calls: a margin of error of around ±10 points, so it says almost nothing yet. That's why we keep counting (Crowd Report).
Try it with free coins. FakeBet gives you real sportsbook odds, 500 free coins to start and a full record of every bet, so you can practice all of this without risking money. Get FakeBet on Google Play.