Flat betting vs percentage staking: how much should you bet?

The three staking plans

Take a starting bankroll of €1,000 set aside only for betting.

• Flat betting: the same stake every time, for example €20 (2% of the starting bankroll). Simple to track, and the stake doesn't react to wins or losses. Many people call this stake one unit.
• Percentage staking: a fixed share of the current bankroll, for example 2%. At €1,000 you stake €20; after a fall to €800 you stake €16; after a rise to €1,500 you stake €30.
• Kelly fraction: the stake depends on your edge. The Kelly criterion says to stake f = (b × p − q) ÷ b of your bankroll, where b is the odds minus 1, p your win chance and q = 1 − p. Most people use a half or a quarter of that because full Kelly swings wildly.

Example for Kelly: odds of 2.10 and a true win chance of 50% give b = 1.10, so f = (1.10 × 0.50 − 0.50) ÷ 1.10 = 4.5% of your bankroll. Half Kelly is about 2.3%, quarter Kelly about 1.1%. At odds of 2.00 and a 48% chance, f comes out negative: Kelly's answer is “don't bet”.

Simulation 1: bets with negative EV

First the normal situation for most bettors: odds of 2.00 with a true win chance of 48%, so every euro staked has an expected value of −4%. We ran 20,000 simulations of 1,000 bets each, starting at €1,000.

Percentage staking falls more slowly because the stakes shrink as the bankroll shrinks. It can never quite reach zero. But it still goes the wrong way, and a typical run lost almost two thirds of the money. No staking plan can turn a negative expected value into a positive one: the expected result is always the total staked times −4%. The only plan that “wins” here is not betting, which is exactly what Kelly says.

Simulation 2: bets with an edge

Now assume you really have an edge: odds of 2.10 on an outcome that wins 50% of the time, an EV of +5% per euro. That is a generous assumption; few bettors manage it over time. Same setup, 1,000 bets from €1,000:

With a real edge, percentage plans compound: winning stretches lead to bigger stakes, so the best outcomes grow far beyond flat staking. Full Kelly has the highest median, but one run in ten still fell below half the starting bankroll, and the worst runs lost three quarters of it. Remember too that Kelly assumes you know your win chance exactly. If you overestimate it, “full Kelly” is really over-betting. That is why fractions are popular.

Drawdowns: the part you feel

A drawdown is the fall from your highest balance to a later low. It matters because it is what makes people abandon a plan or start chasing. Median of the largest drawdown in each run, from simulation 2:

Even with a genuine +5% edge, losing a third of your peak balance at some point is normal. That is variance at work, and it is why staking plans for single bets should be modest.

How arbitrage staking differs

With sure bets, the question “how much on each bet?” has a different answer. You back every outcome of one event at different bookmakers, and the split between the legs is set by the ratio of the odds, so that every outcome pays the same:

odds 2.06 at bookmaker A and 2.02 at bookmaker B, €200 in total
stake A = €200 × (1/2.06) ÷ (1/2.06 + 1/2.02) ≈ €99.02
stake B = €200 × (1/2.02) ÷ (1/2.06 + 1/2.02) ≈ €100.98
return either way ≈ €203.98, a profit of about €3.98 (2.0%)

So the split is not a choice. What you do choose is the total size, and that is limited by practical things rather than by a percentage rule: how much money sits in each bookmaker account, the maximum stake the bookmaker accepts, and how much you can afford to have tied up while bets are open. Because every outcome is covered, there is no losing streak to survive in the usual sense. The real risks are different: an odds change before the second leg, a voided bet, or a limited account. Our arbitrage calculator shows the split, and the guide to starting capital covers how much to spread across accounts.

Which plan suits a beginner

• If you don't know your edge (most people), stakes don't fix that. Keep them small and flat, set a budget, and track results honestly with a bet log.
• If you have a measured edge over hundreds of bets, a small percentage or a quarter Kelly is a sensible middle ground: some compounding, smaller drawdowns.
• For sure bets, let the odds set the split and let your account balances and limits set the size.

Whatever you choose, only bet money you can do without. If you find yourself increasing stakes to win back losses, stop and look at our responsible gambling page.

Frequently asked questions

Is flat betting or percentage staking better?

It depends on whether your bets have an edge. With negative expected value both lose, percentage staking just more slowly. With a real edge, percentage staking compounds and grows faster in good runs, at the cost of somewhat larger drawdowns. Neither plan changes the expected value per euro staked.

How much of my bankroll should I bet per bet?

Many bettors use 1 to 2 percent of their bankroll per single bet. In our simulation with a 5 percent edge, quarter Kelly at about 1.1 percent kept the typical largest drawdown near 25 percent, while full Kelly at 4.5 percent saw drawdowns near 73 percent.

Can a staking plan make losing bets profitable?

No. The expected result of any staking plan is the total amount staked times the expected value per euro. If that value is negative, every plan loses on average; the Kelly formula then recommends staking nothing.

How are stakes set for a sure bet?

Each leg's stake is proportional to one divided by its odds, so every outcome returns the same amount. You only choose the total, which in practice is limited by your account balances and the bookmakers' maximum stakes.

Sources

• Wikipedia: Kelly criterion
• Kelly, J. L. (1956): A New Interpretation of Information Rate. Bell System Technical Journal 35(4)
• Wikipedia: Drawdown
• Wikipedia: Gambler's ruin
• Wikipedia: Arbitrage betting

As of October 2026. Simulation by us: 20,000 runs of 1,000 independent bets each; all figures are worked examples, rounded. Past or simulated results say nothing about your future results.

Betting involves risk, including sure bets: prices move, bets get voided and accounts get limited. Only bet money you can do without. Our responsible gambling page lists free, confidential help.

Not betting, financial, legal or tax advice. 18+. As of October 2026.