CLV calculator

Why CLV beats P&L

Profit over a few hundred bets is mostly noise. A good month can come from luck and a bad one can hide genuinely sharp betting, which is why P&L alone is such a slow and unreliable teacher.

The closing line is the market's best estimate of true probability, arrived at after all available money and information. Beating it repeatedly is hard, and it is hard for reasons that cannot be explained by variance — which is exactly what makes it evidence. CLV tells you whether you are good long before your balance does.

One caveat worth stating plainly: a single bet with strong CLV means nothing. It is a signal that only becomes meaningful across hundreds of bets.

Worked example

Working out a deduction? Use the Rule 4 calculator.

Questions

What is closing line value?

Closing line value (CLV) compares the price you took against the price the market settled at. If you backed a horse at 5.0 and it started at 4.0, you have +25% CLV — you got a better price than the market's final assessment.

Why does CLV matter more than profit?

Profit over a small sample is mostly variance; a losing month tells you very little on its own. The closing line is the market's most accurate estimate of true probability, so consistently beating it is the clearest evidence your results come from judgement rather than luck. CLV converges on the truth far faster than P&L does.

How is CLV calculated?

Divide the odds you took by the closing odds, subtract one, and express as a percentage. 5.0 taken against a 4.0 close is 5.0 / 4.0 − 1 = 0.25, so +25%.

Does a Rule 4 deduction affect CLV?

Yes, and ignoring it overstates your edge. A Rule 4 reduces the price you effectively struck, so the comparison should use that reduced price rather than the one shown on your slip. Most CLV calculators skip this.

What counts as good CLV?

Any consistent positive figure is meaningful, because the closing line is hard to beat. Sustained CLV of a few percent across hundreds of bets indicates a genuine edge. A single bet with high CLV proves nothing.

Should I use SP or the final exchange price?

Either works provided you are consistent. Starting price is the usual reference for horse racing; the final exchange price before the off is generally the sharper benchmark, because it reflects money rather than on-course fluctuations.