Closing Line Value (CLV) in Sports Betting, Explained
Related book: The Sports Investing Blueprint by Ethan Cole · Amazon
Closing line value tells you whether you beat the market’s final price. If the price you took has a lower implied probability than the no-vig closing price on the same side, you got a better number than the close. Tracking it gives you a read on your process long before win-loss results settle down.
The steps below use the same arithmetic as implied probability and the vig. Every price on this page is a made-up example, chosen so the math comes out clean.
What the closing line is
The closing line is the last price offered before a game starts and betting on it stops. By then the market has absorbed injury news, lineup changes, weather and the money that came in all week. That is why many bettors use the close as their benchmark: it is the most informed price the market produced for that bet.
CLV compares the price you took with that final price. You took the earlier price, so if the market later moved toward your side, you got a number the closing market would not give you.
How to measure CLV
Use four steps.
- Convert the price you took into its implied probability.
- Write down the closing prices on both sides of the market.
- Remove the vig from the closing pair, so the two sides add to 100%.
- Subtract: no-vig closing probability on your side minus the implied probability of your price.
A positive result means you beat the close. A negative result means the close was a better price than the one you took.
For a negative American price, drop the minus and call that number A. The implied probability is A / (A + 100). For a positive price P, it is 100 / (P + 100). To remove the vig from a two-way pair, divide each side’s implied probability by the sum of both.
Example: beating the close
You take Side A at -105. The market closes at Side A -120 and Side B +100.
Your price: -105 implies 105 / 205 = 21 / 41, which is 51.22%.
The close: -120 implies 120 / 220 = 6 / 11, which is 54.55%. +100 implies 100 / 200 = 1 / 2, which is 50.00%. The pair adds to 23 / 22, which is 104.55%, so the vig is in there. Side A’s no-vig share is (6 / 11) ÷ (23 / 22) = 12 / 23, which is 52.17%.
CLV = 12 / 23 − 21 / 41 = 9 / 943, which is +0.95 percentage points.
| Step | Exact | Displayed |
|---|---|---|
| Price taken (-105) | 21 / 41 | 51.22% |
| Close, Side A (-120) | 6 / 11 | 54.55% |
| Close, Side B (+100) | 1 / 2 | 50.00% |
| No-vig close, Side A | 12 / 23 | 52.17% |
| CLV | 9 / 943 | +0.95 pts |
Comparing -105 with -120 directly gives 54.55% − 51.22% = 3.33 points. That bigger figure counts the vig on the closing price as if it were part of your edge. The no-vig comparison is the fairer one.
What that is worth in expected value
Suppose the no-vig close, 12 / 23, were the true chance of Side A winning. A $100 stake at -105 profits 2,000 / 21 if it wins, which is $95.24.
EV = (12 / 23 × 2,000 / 21) − (11 / 23 × 100) = 24,000 / 483 − 23,100 / 483 = 900 / 483 = 300 / 161
300 / 161 is 1.8633…, displayed +$1.86 on $100. The same bet at the closing price of -120 profits 250 / 3 on $100, displayed $83.33, and its EV at that chance is −100 / 23, displayed −$4.35, because -120 needs 54.55% to break even. The method is laid out step by step in expected value in sports betting.
Example: the close moves against you
You take Side A at -110. The market closes at Side A +100 and Side B -120.
Your price: -110 implies 110 / 210 = 11 / 21, which is 52.38%.
The close: Side A at +100 is 1 / 2 and Side B at -120 is 6 / 11. Side A’s no-vig share is (1 / 2) ÷ (23 / 22) = 11 / 23, which is 47.83%.
CLV = 11 / 23 − 11 / 21 = −22 / 483, which is −4.55 percentage points. If the no-vig close were the true chance, the EV of $100 at -110 would be (11 / 23 × 1,000 / 11) − (12 / 23 × 100) = −200 / 23, displayed −$8.70.
| Price taken | No-vig close | CLV | EV on $100 at the close |
|---|---|---|---|
| -105 (51.22%) | 52.17% | +0.95 pts | +$1.86 |
| -110 (52.38%) | 47.83% | −4.55 pts | −$8.70 |
Either bet can win or lose tonight. CLV grades the price you got, not the result.
Why CLV beats win-loss for feedback
Results take a long time to say anything. At prices near -110, a few dozen bets can swing well above or below the long-run average on luck alone. Understanding variance covers why a short record is a noisy grade.
CLV is measured on every bet the moment the game starts, whether it wins or loses. A record of consistently beating the close says your timing and price selection are adding value. A record of consistently losing to the close says the market keeps moving away from you, even through a hot streak.
How to get better CLV
Line shopping is the most direct lever. Comparing legal books before you bet means you start from the best available number, so even when the market moves against you, you lose less to the close.
Timing is the other lever. Prices move as news arrives. If your read on a game comes before the market prices it in, the earlier number is the one worth taking.
Keeping a CLV log
Add a few columns to your bet record: the price you took, both closing prices, the no-vig close on your side, and the CLV in points. Use one consistent source for closing prices so the comparison means the same thing every time.
The American odds to implied probability table covers the conversions, and the bankroll and line-shopping worksheet is a ready place to keep the stake next to each price. Keep stakes sized to a separate bankroll, as in bankroll management and unit sizing; good CLV does not change how much you can afford to lose.
Bottom line
CLV is the no-vig closing probability on your side minus the implied probability of the price you took. Taking -105 on a side that closes -120 / +100 beats the close by 0.95 points. Taking -110 on a side that closes +100 / -120 loses to it by 4.55 points. Shop for the best number, track CLV on every bet, and judge your process on it over time rather than on last week’s record.
For how price, records and bankroll fit together into one system, see the book.