Value betting masterclass · Module 3: Staking and variance · Lesson 14 of 25 · About 7 min
Betting records are the only reliable way to see how your bets are really going. Memory tends to hold on to the big winners and blur everything else, so a simple log keeps you honest.
This guide covers what to write down, how to calculate ROI and yield, and how closing line value tells you whether an edge is genuine or just good fortune.
Read the transcript
Without a record of your bets, there's no real way to know whether you have an edge. Here's what's worth keeping.
Log every single bet. The date, the sport and market, the odds you took and the closing odds, your stake and result, and the bookmaker you used.
From that you get two useful measures. Yield is your profit divided by everything you've staked. Return on bankroll is your profit divided by the bankroll you started with.
Here are five bets. Judged on results, the yield is minus fourteen per cent. But on average they beat the closing price by three point two per cent. The prices were good, and the results were just unlucky.
Results are noisy, and even five hundred bets can't prove an edge on their own. Closing line value gives a faster signal, because it doesn't depend on results. The free Bet Tracker on ValueBets.uk does all of this for you. Keep honest records, and please bet responsibly.
Key points
- 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, and even 500 bets can’t prove an edge by themselves.
- Closing line value (CLV) gives a quicker signal because it doesn’t depend on results.
Why records matter
A log swaps guesswork for facts. You can see your real profit, your average odds and which markets suit you best.
Records also help you stay within budget. When the month’s total stakes are in front of you, it is much harder to drift past your limit, so a log is as much a safer gambling tool as a maths one.
And records let you test your ideas. You might believe you read over 2.5 goals (Lesson 16 out of 25 in the Masterclass) prices well, and a log will show whether the numbers back that up.
What to write down
Use one row per bet. A spreadsheet is ideal, but a notebook works too. These eight columns are the ones that count:
- Date: when you placed the bet, not when it settled.
- Sport: football, tennis, racing and so on.
- Market: match result, both teams to score, over 2.5 goals and so on.
- Odds taken: the decimal price you actually got.
- Closing odds: the price just before the start.
- Stake: the amount you bet, in pounds.
- Result: won, not won, void or half-won, with the amount returned.
- Bookmaker: where you placed it.
Fill in the row as soon as you place the bet, then add the closing odds and result afterwards. Leave it until the end of the week and the details slip. Give free bets and boosts their own rows, so they don’t flatter your everyday results. The free Bet Tracker has all of these columns ready to go.
Yield and ROI: two different measures
ROI and yield are often used as if they were the same, but they answer different questions.
Yield is profit divided by total staked, so it shows your return for each £1 bet. 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, so it shows how your betting pot has changed. It depends on how hard you work that pot, which means high turnover can make a small edge look big.
The calculator below works out profit, ROI and yield from your own numbers.
ROI and yield calculator
How CLV shows whether your edge is real
Results take a very long time to settle down. Every bet carries a large slice of luck, so short-term profit tells you little. Our betting variance (Lesson 13 out of 25 in the Masterclass) guide explains why.
Closing line value (Lesson 9 out of 25 in the Masterclass) helps cut through that. CLV % is the odds taken divided by the closing odds, minus 1. If you regularly get better prices than the market finishes at, you are probably judging prices well, whatever your recent results look like.
So your records need that closing odds column. Without it you only have results, and results on their own are slow to tell you anything. Some bettors compare with the closing price after the margin is removed, which is a tougher test, and our fair odds (Lesson 3 out of 25 in the Masterclass) guide shows how.
A sample record, worked through
Here are five bets from an example log so you can follow the maths. Bookmakers are shown as A to C to keep the focus on the numbers.
| Date | Sport and market | Odds taken | Closing odds | Stake | Returned | CLV | Bookmaker |
|---|---|---|---|---|---|---|---|
| 3 Nov | Football, over 2.5 goals | 2.20 | 2.05 | £10 | £22.00 | +7.3% | A |
| 3 Nov | Football, both teams to score | 1.95 | 1.88 | £10 | £0.00 | +3.7% | B |
| 4 Nov | Tennis, match winner | 2.60 | 2.50 | £8 | £20.80 | +4.0% | A |
| 5 Nov | Football, home win | 3.40 | 3.10 | £5 | £0.00 | +9.7% | C |
| 6 Nov | Football, under 2.5 goals | 1.85 | 1.80 | £10 | £18.50 | +2.8% | B |
Worked example
Total staked: £10 + £10 + £8 + £5 + £10 = £43. Total returned: £22.00 + £20.80 + £18.50 = £61.30, so profit is £18.30.
That gives a yield of £18.30 ÷ £43 = 42.6%. It looks brilliant, but most of it is down to three bets landing in a row.
Now look at the CLV column. The average is (7.3 + 3.7 + 4.0 + 9.7 + 2.8) ÷ 5 = 5.5%, and all five bets beat the closing price.
Five bets prove nothing either way. But a steady positive CLV over hundreds of bets is a much more trustworthy sign than a yield that will swing a long way as more results come in.
How many bets does a record need?
More than most people expect. Suppose you place 500 bets of £10 at average odds of about 2.20. That is £5,000 staked, and if you finish £150 up your yield is 3%. With a £1,000 starting bankroll, your ROI on bankroll is 15%.
That sounds good. But ordinary luck can shift the yield on 500 bets at those odds by about 5 percentage points either way (one standard deviation), so a 3% yield sits well within the noise. It could be skill or it could be chance.
That is why consistent positive CLV matters more than a short profitable spell.
Keeping your records honest
- Log every single bet. Leaving out the awkward ones makes the whole record worthless.
- Record the price you got, not the best price you spotted later.
- Take closing odds from one source, such as the Betfair Exchange, so your CLV is consistent.
- Review once a month, not after every bet, so a single result doesn’t steer your decisions.
- Set your limits first. If the log shows you betting more than planned, stop and reset your budget.
Remember too that bookmakers can legally limit accounts for commercial reasons. A Gambling Commission review of 2024 data found 4.31% of active accounts at large online bookmakers had some kind of restriction, and your records will show you if it happens to you.
Related guides
- Value betting explained (Lesson 1 out of 25 in the Masterclass)
- Expected value betting (Lesson 4 out of 25 in the Masterclass)
- Bankroll management (Lesson 11 out of 25 in the Masterclass)
- The Kelly criterion (Lesson 12 out of 25 in the Masterclass)
- Betting account restrictions (Lesson 22 out of 25 in the Masterclass)
Lesson 14 of 25 · Staking and variance
18+ only. Betting should stay fun. Set a budget before you start, only bet what you can comfortably afford, and take a break whenever you need one. For free, confidential support, visit BeGambleAware.org or call the National Gambling Helpline on 0808 8020 133.