Betting records are the only honest way to know how your bets are really doing. Memory is kind to wins and quick to forget losses, so a simple log keeps you straight.
This guide shows you what to log, how to work out ROI and yield, and how closing line value tells you whether an edge is real or just luck.
The short version
- Log every bet: date, sport, market, odds taken, closing odds, stake, result and bookmaker.
- Yield is profit divided by total staked. ROI on bankroll is profit divided by your starting bankroll.
- Results are noisy. Even 500 bets can’t prove an edge on their own.
- Closing line value (CLV) gives a faster signal, because it doesn’t depend on results.
Why betting records matter
A log replaces guesswork with facts. So you can see your real profit, your average odds and which markets cost you most.
Good betting records also help you stick to a budget. When you can see the total you have staked this month, it is much harder to drift past your limit. In short, a record is a safer gambling tool as much as a maths tool.
Finally, records let you test ideas. For example, you might think you judge over 2.5 goals prices well. A log will show whether the numbers agree.
What to log in your betting records
Keep one row per bet. For example, a spreadsheet works well, but a notebook is fine too. These are the 8 columns that matter:
- Date: the day you placed the bet, not the day it settled.
- Sport: football, tennis, racing and so on.
- Market: for example, match result, both teams to score or over 2.5 goals.
- Odds taken: the decimal price you actually got.
- Closing odds: the price just before the event started.
- Stake: the amount you risked, in pounds.
- Result: won, beaten, void or half-won, plus the profit in pounds.
- Bookmaker: where you placed it.
Fill in the row when you place the bet, then add the closing odds and result later. If you wait until the end of the week, you will forget the misses first. Also, log free bets and boosts in their own rows, so they don’t flatter your normal results.
ROI vs yield: two ways to measure betting records
People often use ROI and yield as if they mean the same thing. However, they answer different questions.
Yield is profit divided by total staked. It tells you your return for each £1 you bet. So it is the fairest way to compare two bettors, or two markets, with very different volumes.
ROI on bankroll is profit divided by your starting bankroll. It tells you how your betting pot has changed. But it depends on how hard you bet that pot, so a bigger turnover can make a small edge look large, or a small dip look huge.
Use the calculator below to work out profit, ROI and yield from your own figures.
ROI and yield calculator
How CLV shows whether your edge is real
Results take a very long time to settle down. That is because each bet has a large element of luck, so short-term profit says little. You can read more about this in our guide to betting variance.
Closing line value helps here. CLV % is the odds taken divided by the closing odds, minus 1. If you often get better prices than the market settles on, that suggests you are judging prices well, even during a bad run.
That means your betting records need the closing odds column. Without it, you only have results, and results alone are slow to tell you anything. Note that some bettors use the no-margin closing price, which is a stricter test. Our guide to fair odds shows how to remove the margin.
A worked example of betting records
Below are 5 bets from a sample log, so you can see the maths. The bookmakers are labelled A to C to keep the focus on the maths.
| Date | Sport and market | Odds taken | Closing odds | Stake | Profit | CLV | Bookmaker |
|---|---|---|---|---|---|---|---|
| 12 Oct | Football, over 2.5 goals | 2.10 | 1.95 | £10 | +£11.00 | +7.7% | A |
| 12 Oct | Football, both teams to score | 1.90 | 1.85 | £10 | −£10.00 | +2.7% | B |
| 13 Oct | Tennis, match winner | 2.50 | 2.60 | £8 | −£8.00 | −3.8% | A |
| 14 Oct | Football, home win | 3.20 | 3.00 | £5 | +£11.00 | +6.7% | C |
| 15 Oct | Football, under 2.5 goals | 1.80 | 1.75 | £10 | −£10.00 | +2.9% | B |
Worked example
First, add up the stakes: £10 + £10 + £8 + £5 + £10 = £43. Next, add up the profit: £11 − £10 − £8 + £11 − £10 = −£6.
So the yield is −£6 ÷ £43 = −14.0%. On results alone, this looks poor.
Now check the CLV column. The average is (7.7 + 2.7 − 3.8 + 6.7 + 2.9) ÷ 5 = about +3.2%. Also, 4 of the 5 bets beat the closing price.
In short, the results are negative but the prices were mostly good. Of course, 5 bets prove nothing either way. But if that pattern holds over hundreds of bets, it is a far better sign than a lucky profit.
How many bets do betting records need?
More than most people think. For example, say you place 500 bets of £10 at average odds of about 2.20. That is £5,000 staked. If you finish £150 up, your yield is 3%. With a £1,000 starting bankroll, your ROI on bankroll is 15%.
At first, that sounds good. However, normal luck alone can move the yield on 500 bets at those odds by about 5 percentage points either way (one standard deviation). So a 3% yield is well inside the noise. It could be skill, or it could be chance.
This is why steady positive CLV matters more than a short profit run.
Keep your betting records honest
- Log every bet. Leaving out the bad ones makes the whole record useless, because the gaps hide your losses.
- Record the price you got, not the best price you saw later.
- Take the closing odds from one source, such as Betfair Exchange, so your CLV is consistent.
- Review monthly, not after every bet, so one result doesn’t drive your choices.
- Set limits first. If your log shows you are betting more than you planned, stop and reset your budget.
Also, keep in mind that bookmakers can legally limit accounts for commercial reasons. A Gambling Commission review of 2024 data found that 4.31% of active accounts at large online firms were restricted in some way. Your record will show you this happening, too.
Related guides
- Value betting explained
- Expected value betting
- Bankroll management
- The Kelly criterion
- Betting account restrictions
18+ only. Betting should be fun, and every bet can lose. Set a budget you can afford to lose and stick to it. For free, confidential support, visit BeGambleAware.org or call the National Gambling Helpline on 0808 8020 133.