ROI = net profit ÷ total amount staked × 100. On £400 staked and £420 returned: net profit +£20, ROI +5%. ROI measures an observed performance on bets already settled. On its own, it doesn't tell you whether that performance is significant or whether it will repeat. Read it with the volume, the average odds and the variance they produce.
ROI in two sentences
ROI sets the net profit of your bets against the total you staked. ROI = net profit ÷ total amount staked × 100. On £400 staked and £420 returned, net profit is +£20 and ROI is +5%.
It's an observed performance, not a demonstrated one. An ROI only means something once you know how many bets produced it and the average odds they were taken at.
Net profit and volume staked
Net profit on its own tells you very little. Two records can show the same gain on very different volumes. +£40 on £100 staked is an ROI of 40%. +£40 on £4,000 staked is 1%.
ROI exists to compare those two situations. It scales the result to the volume staked, which net profit doesn't do.
The formula
ROI = net profit ÷ total amount staked × 100. Net profit is the sum of returns collected minus stakes, across every settled bet.
This page uses the most common convention: ROI measured against total stakes. Another one circulates under the same name. It measures profit against average bankroll and is sometimes called "yield". The denominator changes, but the idea stays close. Always state the base before comparing two figures, including your own from one period to the next.
Calculate a net profit and an ROI
Enter the total staked and the total returned over the period you're looking at.
The sum of every stake already settled over the period observed.
The sum of every return collected on those same bets, winnings included.
Result
- Net profit
- +€20.00
- ROI
- +5.00%
Warning:
ROI describes a performance observed on the bets entered. It says nothing about whether it is significant or reproducible.
ROI or yield: what the two words cover
In everyday use, ROI and yield describe the same calculation. Where a difference exists, it sits in the denominator: total staked for one, average bankroll committed for the other. There's no separate page for yield. The intent behind the two words is too close to justify two URLs.
The break-even point by odds
At given average odds, there's a minimum strike rate below which you lose money: 1 ÷ average odds. At average odds of 1.50, you need about 66.7% to avoid losing. At 2.50, you need 40%.
| Average odds | Break-even point (1 ÷ odds) |
|---|---|
| 1.50 | 66.7% |
| 2.00 | 50.0% |
| 2.50 | 40.0% |
| 3.00 | 33.3% |
This threshold is why a strike rate never reads on its own. A 55% strike rate gives a clearly negative result at average odds of 1.50 (break-even 66.7%). At 2.50 it sits well above break-even (40%), so the result is positive.
Two profiles, same number of bets
A strike rate can rank two records in the opposite order to their ROI. Two punters, 20 bets each, £10 a bet, £200 staked on each side.
| Indicator | Profile A | Profile B |
|---|---|---|
| Bets won | 10 / 20 | 8 / 20 |
| Strike rate | 50% | 40% |
| Average odds | 1.50 | 2.50 |
| Returns collected | £150 | £200 |
| Net profit | −£50 | £0 |
| ROI | −25% | 0% |
The gap between these two profiles is easy to see. A wins 10 bets out of 20, B only 8, and yet it's B that ends up level. A strike rate means nothing without the average odds beside it.
"+20% ROI, my method works."
Without the number of bets and the average odds behind that figure, you can't interpret it. A high ROI over a handful of bets looks a lot like a lucky run.
10 bets at +30% or 2,000 bets at +3%?
Take two records: 10 bets at +30% ROI, and 2,000 bets at +3%. Is the first one better? You can't tell from those figures alone. You'd need the variance, the sample size, the stability of the odds and the period covered.
Profit is an amount. ROI is that amount set against the volume staked. Bankroll growth tracks how your capital changes, and it also depends on stake sizes and how they vary.
An ROI of +30% over 10 bets sits almost entirely inside the range variance produces on a sample that small. An ROI of +3% over 2,000 bets has far less room to be explained by luck alone. That doesn't guarantee it will repeat.
Why variance dominates on a small sample →
What determines how much data you need to decide →
What ROI doesn't tell you
ROI says nothing about the risk taken to get it, or about the quality of the prices the bets were placed at. Two records with the same final ROI can have gone through very different dips in capital.
A positive ROI doesn't prove a method holds up over the long run. A negative ROI doesn't prove the opposite: over a small sample, both can come from variance.
What the final ROI never shows: the path taken →
The data you need to keep to calculate it
An honest ROI needs a complete record, losses included, with no period erased. The tracking method, column by column, has a page of its own.
The data to record for every bet →
ROI looks at what happened. Expected value describes what should happen on average, if the estimate behind it is sound. It's the next step towards understanding why a result often drifts from what was expected.
Responsible gambling: a good ROI over one period tells you nothing about the next. Sports betting carries a risk of financial loss. Set yourself a budget, don't chase your losses, and use the deposit limits and self-exclusion tools available. Learn more about responsible gambling.
Put it into practice
Apply this guide to real odds.
See a market reading
A real match with its odds, movements and 0-100 signal.
Open the demoMargin calculator
Measure a bookmaker's margin on any market.
Calculate the marginDig into the market
Odds movements are only part of the story. Here are the next topics to read.
Profitability and risk: the complete guide
The full picture: profit, ROI, expected value, variance, sample size, drawdown, risk.
Read the guideTracking your bets
The data to record so you can calculate an honest ROI.
See how to trackVariance: why results swing
What separates a solid ROI from one down to luck.
Understand varianceHow many bets does it take to judge a performance?
What the reliability of an observed ROI depends on.
See the methodDrawdown: measuring the dips in a bankroll
What the final ROI never shows: the path taken to get there.
Understand drawdownAssessing a tipster
Why a high strike rate can hide a negative ROI.
See the methodFrequently asked questions
How do you calculate the ROI of a betting record?
Divide net profit (returns collected minus stakes) by total staked, then multiply by 100. A £20 profit on £400 staked gives an ROI of +5%.
What's the difference between ROI and yield?
In everyday sports betting talk, the two words mean the same calculation: net profit divided by total staked. Some conventions use total stakes, others use average bankroll. Always say which base you're using before comparing two figures.
Is an ROI of +10% a good result?
It depends on the number of bets and the average odds behind it. A +10% over 15 bets is almost entirely down to variance. The same figure over 3,000 bets tells a very different story.
Does ROI measure skill?
Not on its own. It describes what happened over a set of settled bets. It says nothing about the risk you went through to get there, or how likely it is to happen again.
What is the break-even point by odds?
It's the minimum strike rate you need to avoid losing money at given average odds: 1 ÷ average odds. At 1.50 you need about 66.7%. At 2.50, 40% is enough.
Why can two identical ROIs describe different situations?
Because ROI says nothing about volume, average odds or the variance that comes with them. An ROI of +5% over 20 bets and +5% over 3,000 bets don't carry the same weight of evidence.
Sources & methodology
This page draws on the standard definition of return on investment applied to betting, on academic research estimating expected loss rates in betting markets, on the Gambling Commission and BeGambleAware, and on OddScore's odds analysis method.
- Calculate ROI as net profit against total amount staked, and never against average bankroll without saying so.
- Treat a positive ROI as an observed performance on a given record, not as proof of repeatable skill.
- Read an ROI alongside the number of bets and the average odds that produced it.
- Distinguish ROI from yield when two calculation conventions circulate under the same name.
- Whelan, K. (2025). Estimating expected loss rates in betting markets: theory and evidence. Applied Economics.
- Hegarty, T. & Whelan, K. (2026). Market structure and prices in online betting markets. Oxford Economic Papers, 78(1), 90-113.
- Gambling Commission: information for players
- BeGambleAware: free support and advice