Kelly stake
Turn an edge and a bankroll into a disciplined stake. Bet bigger when the edge is bigger — and never more than your bankroll can survive.
| Fraction | Bet size | Stake |
|---|---|---|
| Full Kelly | 2.5% | $25.00 |
| Half KellyDefault | 1.3% | $12.50 |
| Quarter Kelly | 0.6% | $6.25 |
Full Kelly is aggressive and assumes your edge estimate is exactly right. Because real edges are uncertain, most disciplined bettors use half or quarter Kelly to cut variance and protect their bankroll. Bet within your means.
Find the +EV bets worth sizing
EVSTREAM flags positive-EV prices live, so you know what to stake on
Bet bigger when the edge is bigger.
- ▸Kelly maximises long-run growth. Stake too little and you leave money on the table; too much and a losing run can wipe you out. Kelly is the mathematically optimal middle.
- ▸Fractional Kelly tames variance. Half Kelly keeps ~75% of the growth with far smaller swings. When your edge estimate is uncertain — and it always is — fractional is the safer call.
- ▸No edge, no bet. If the price is −EV, Kelly returns zero — there’s no stake that grows a bankroll on a bad bet. The tool flags it instead of suggesting a number.
Kelly staking, answered.
How much to bet — without the guesswork.
What is the Kelly criterion?
A staking formula that sizes each bet in proportion to your edge and the odds, to maximise the long-run growth rate of your bankroll. Bigger edge → bigger stake; no edge → no bet.
Should I use full, half or quarter Kelly?
Most experienced bettors use half or quarter. Full Kelly is theoretically optimal only if your probability is exactly right — but estimates are noisy, so full Kelly tends to over-bet. Fractional Kelly sacrifices a little growth for much smaller drawdowns.
Why does it sometimes say "no bet"?
When your true-chance estimate implies the price is −EV, the Kelly fraction is zero or negative. There's no positive stake that grows a bankroll on a −EV bet, so the tool tells you to pass rather than invent a number.
How does this relate to the EV calculator?
Directly — the numerator of the Kelly formula is the EV fraction. Use the EV calculator to confirm a bet is +EV, then use Kelly here to decide how much to stake.
Find the edge. Size it right.
EVSTREAM surfaces the +EV bets across 60+ books in real time. Bring the price and edge straight into this calculator and stake with discipline.