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Bankroll Management Tracker & EV Calculator
Two tools in one: find out whether a bet offers positive expected value (+EV) before you place it, then work out the right stake for your bankroll. Below the tools you’ll find a full guide to odds conversion, unit sizing, and the five bankroll rules that separate long-term winners from the rest.
Expected Value (EV) Calculator
Enter your own probability estimate and the bookmaker’s odds to see if the bet has mathematical edge
How is EV calculated?
EV = (Your Probability × Decimal Odds) − 1. A positive result means the bet is priced in your favour over the long run. A negative result means the bookmaker holds an edge.
Unit Size Calculator
Find out how much to stake per bet based on your total betting bankroll
Recommended stake tiers for a £0 bankroll:
Odds Converter
Instantly convert between decimal, fractional, American, and implied probability
The Maths Behind Winning
What Is Expected Value in Sports Betting?
Every bet you place has an expected value — a number that tells you, on average, how much you win or lose per pound staked over a large sample of identical bets. Finding bets where EV is positive is the entire foundation of professional sports betting.
When a bookmaker prices an event, they build a margin (also called the overround or vig) into the odds. This margin is what gives them their long-term profit. To beat them, you need to identify situations where your own probability estimate is more accurate than theirs.
The EV formula is straightforward:
EV = (Your Probability × Decimal Odds) − 1
If the result is above zero, the bet has positive expected value and is worth considering. If it is below zero, you are paying for the privilege of betting, on average.
A quick example
| Scenario | Bookie Odds | Your Prob. | EV | Verdict |
|---|---|---|---|---|
| Home win | 2.10 | 55% | +15.5% | ✓ +EV |
| Home win | 1.80 | 55% | −1.0% | ✗ −EV |
| BTTS Yes | 1.95 | 50% | −2.5% | ✗ −EV |
| Draw | 3.40 | 32% | +8.8% | ✓ +EV |
Odds Converter Guide
Understanding Betting Odds Formats
Different sportsbooks use different odds formats. Knowing how to read and convert between them quickly gives you a significant edge when line-shopping across bookmakers.
The three main formats
Used in the UK, Europe, and most international sportsbooks. The figure represents your total return per £1 staked, including your stake back. Odds of 3.00 return £3 for every £1 wagered — a £2 profit plus your £1 back. Convert to implied probability: divide 1 by the decimal odds. 3.00 = 33.3% implied probability.
Traditional UK betting shop format. The left number shows profit for every right-number staked. At 5/2, you profit £5 for every £2 wagered, getting £7 total back. To convert to decimal: divide the left by right, then add 1. 5/2 = (5÷2)+1 = 3.50.
Standard in the US. Positive numbers (+150) show profit on a £100 stake. Negative numbers (−200) show how much you must stake to win £100. To convert +150 to decimal: (150÷100)+1 = 2.50. For −200: (100÷200)+1 = 1.50.
| Decimal | Fractional | American | Implied % |
|---|---|---|---|
| 1.50 | 1/2 | −200 | 66.7% |
| 2.00 | Evens | +100 | 50.0% |
| 2.50 | 6/4 | +150 | 40.0% |
| 3.00 | 2/1 | +200 | 33.3% |
| 4.00 | 3/1 | +300 | 25.0% |
| 6.00 | 5/1 | +500 | 16.7% |
| 11.00 | 10/1 | +1000 | 9.1% |
Five Bankroll Rules Every Bettor Should Know
Most bettors focus on finding winners. The professionals focus on not going broke while doing it. These five principles protect your bankroll through losing runs — and every bettor has losing runs.
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01
Treat your bankroll as entertainment spend Decide in advance what you can comfortably afford to lose over a month or a season. This becomes your total bankroll. It should come from discretionary income only — never from rent, bills, or savings. Once the budget is set, do not top it up in the same period if you lose it.
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02
Divide into 100 units and risk no more than 3–5 at a time A unit is 1% of your total bankroll. On a £200 bankroll, one unit is £2. Most winning bettors stake between one and three units per bet on confident selections and half a unit or less on longer shots. This sizing ensures a twenty-bet losing run — which happens to everyone — does not wipe you out.
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03
Flat stake or Kelly — pick a system and stick to it Flat staking means every bet gets the same unit size regardless of confidence. It is the simplest and most forgiving approach. The Kelly Criterion sizes stakes in proportion to your estimated edge — more sophisticated but requires honest probability estimates. Mixing the two, or changing approach bet-to-bet, is worse than either.
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04
Never chase losses When you are losing, the temptation is to stake more to win it back quickly. This is the single most common cause of bankroll destruction. Your staking plan exists precisely for losing runs. Chasing losses with bigger bets turns a manageable drawdown into a financial problem. The discipline to keep staking the same amount after a loss is what separates bettors who survive from those who do not.
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05
Track every bet and review monthly Without records, you cannot know whether you are genuinely profitable or just lucky. Log the date, event, market, odds, stake, and result for every bet. Review monthly: which markets are performing, which are draining your bankroll, what your ROI looks like per sport or per bookmaker. The numbers will tell you the truth your gut will not.
Bankroll Management FAQ
Answers to the questions bettors ask most often.
