Betting Strategy · 2026-07-16 · By Moneyline Staff · 7 min read
Bankroll Management for Sports Betting: Unit Sizing Explained
Updated July 2026
Bankroll management for sports betting is the practice of setting aside a fixed sum you can afford to lose (your bankroll), then risking a small, consistent percentage of it on each bet. The standard range is 1 to 5 percent per wager, with 1 to 2 percent being the sharp default.
Most bettors do not go broke because they pick the wrong side. They go broke because they bet too much on the wrong side. Bankroll management is the boring discipline that separates people who last from people who reload their account every month.
Key numbers to know
- Standard unit size range: 1 to 5 percent of bankroll per bet, with 1 to 2 percent as the common sharp default.
- At standard -110 odds you need to win 52.4 percent of your bets just to break even.
- The Kelly Criterion, published by physicist John L. Kelly Jr. in a 1956 Bell System Technical Journal paper, gives a formula for the mathematically optimal bet size when you have a real edge.
What is a bankroll, and how big should it be?
Your bankroll is money set aside strictly for betting. It is not your rent, it is not your grocery budget, and it is not money you need back for anything real. The first rule of bankroll management is that this number should be an amount you can lose entirely without changing your life.
What percentage of my bankroll should I bet?
Between 1 and 5 percent per bet, with 1 to 2 percent the recommended default for most bettors. Under 1 percent is very conservative, and above 5 percent exposes you to serious risk of ruin during normal losing streaks.
What is a betting unit?
A unit is one standard bet, expressed as a fixed percentage of your bankroll. The common baseline is 1 unit equals 1 percent of your bankroll. Conservative bettors use 1 percent, moderate bettors use 2 percent, and aggressive bettors push toward 3 to 5 percent.
What is a unit in sports betting?
A unit is one standard bet expressed as a fixed percentage of your bankroll, commonly 1 percent. If your bankroll is $1,000 and a unit is 1 percent, then 1 unit equals $10.
| Bankroll | 1% unit (conservative) | 2% unit (moderate) | 5% unit (aggressive) |
|---|---|---|---|
| $500 | $5 | $10 | $25 |
| $1,000 | $10 | $20 | $50 |
| $5,000 | $50 | $100 | $250 |
Flat betting vs percentage betting vs Kelly
| Method | How it works | Best for |
|---|---|---|
| Flat betting | Bet the same dollar unit every time, based on your starting bankroll. Recalculate occasionally, not after every bet. | Almost everyone. The simplest and most durable method. |
| Percentage betting | Bet a set percentage of your current bankroll, so your unit shrinks when you lose and grows when you win. | Bettors who want built-in downside protection and slower, compounding growth. |
| Kelly Criterion | Sizes each bet by your estimated edge and the odds. Powerful but punishing if your edge estimate is wrong. | Advanced bettors who can accurately estimate their edge, usually at half Kelly. |
Is flat betting or percentage betting better?
Flat betting is simpler and works well for the vast majority of bettors. Percentage betting adds built-in protection because your bets shrink after losses, but it grows your bankroll more slowly.
What is the Kelly Criterion?
The Kelly Criterion gives a formula for the optimal fraction of a bankroll to wager when you have an edge, a principle first set out by physicist John L. Kelly Jr. in his 1956 Bell System Technical Journal paper. In practice, most bettors deliberately stake below full Kelly to survive the swings.
A worked example with real math
Why do I need to win more than 50 percent to profit?
At standard -110 odds you need to win 52.4 percent of your bets just to break even. Sizing bets sanely is what keeps you in the game long enough for a real edge above that line to actually show up.
Say your bankroll is $1,000 and you are a moderate flat bettor at 2 percent. That makes 1 unit equal to $20. A standard single bet is 1 unit, so you risk $20 at -110. If it wins, you profit about $18.18.
Now imagine you lose 5 in a row, a completely normal streak. You are down $100, or 10 percent. Annoying, but survivable. You still have 45 units left to work with.
Compare that to a bettor with the same $1,000 who fires $250 "when they feel it." Five losses and they are broke. Same picks, same skill, completely different outcome.
Common bankroll management mistakes
- Chasing losses by increasing bet size after a bad night.
- Betting scared money you cannot actually afford to lose.
- Using inconsistent unit sizes based on gut feel instead of a fixed plan.
- Never tracking results, so you cannot tell if your process is actually working.
How this connects to smarter betting
Bankroll management is the foundation everything else sits on. It works alongside, not instead of, finding a real edge. If you are also working on estimating your own probabilities rather than just following the market, our guide on how to build a sports betting model walks through turning a probability estimate into an actual betting edge, using the same $100 style worked math as above. Keep the two disciplines separate: your model tells you what to bet on, and your unit sizing tells you how much, and mixing the two together is one of the fastest ways to undo a genuine edge.
Frequently asked questions
What percentage of my bankroll should I bet?
Between 1 and 5 percent per bet, with 1 to 2 percent the recommended default for most bettors. Under 1 percent is very conservative, and above 5 percent exposes you to serious risk of ruin during normal losing streaks.
What is a unit in sports betting?
A unit is one standard bet expressed as a fixed percentage of your bankroll, commonly 1 percent. If your bankroll is $1,000 and a unit is 1 percent, then 1 unit equals $10.
Is flat betting or percentage betting better?
Flat betting is simpler and works well for the vast majority of bettors. Percentage betting adds built-in protection because your bets shrink after losses, but it grows your bankroll more slowly.
What is the Kelly Criterion?
It is a formula, published by John L. Kelly Jr. in 1956, that calculates the optimal bet size based on your edge and the odds.
Why do I need to win more than 50 percent to profit?
Because of the vig. At standard -110 odds you risk $110 to win $100, so you need to win about 52.4 percent of your bets just to break even.
The bottom line
Bankroll management will not make you a winning bettor by itself, but bad bankroll management can turn a winning process into a losing one. Fix your unit size before you worry about anything else.
Related reading: run line vs moneyline in MLB, live betting strategy, what is closing line value, puck line vs moneyline, teaser vs parlay, what is vig in betting, what is a moneyline bet.
21+ where legal. Bet only what you can afford to lose. Betting carries real financial risk and there are no guaranteed outcomes. If gambling stops being fun or feels out of control, call 1-800-GAMBLER for confidential help.
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