Talk to any disciplined bettor and you'll hear the word "units." It's how they keep bet sizes consistent and comparable — and how they stop a bad night from becoming a disaster.
Define your unit
A unit is a fixed percentage of your bankroll, usually 1–2%. If your bankroll is $2,000 and a unit is 1%, one unit is $20. Every bet is then measured in units, not dollars, which makes results comparable over time and across bankroll sizes.
Flat betting vs. variable stakes
Flat betting means every wager is exactly one unit, regardless of confidence. It's the simplest, safest approach and it removes emotion from sizing entirely — a great default for most bettors.
Some bettors vary between, say, one and three units based on perceived edge. That can improve returns if your confidence is well-calibrated, and hurt them badly if it isn't. When in doubt, flat-bet.
Where Kelly comes in
The Kelly criterion is a formula that sizes bets according to your edge and the odds, maximizing long-run growth. Full Kelly is aggressive and swingy, so most who use it bet a fraction — half or quarter Kelly — to smooth the ride.
Kelly requires an accurate estimate of your edge, which most bettors don't have. If you can't reliably estimate your edge, flat unit betting is safer and nearly as good.
Key takeaways
- A unit is a fixed 1–2% of your bankroll.
- Measure bets in units, not dollars.
- Flat betting is the safe default; vary stakes only if well-calibrated.
- Fractional Kelly optimizes growth but needs an accurate edge estimate.
