A CS2 bettor can win ten bets in a row by luck and lose ten in a row with a sound process. Win-loss records take a long time to tell the two apart. Closing line value is the shortcut serious bettors use: instead of asking "did it win?", it asks "did I get a better price than the market settled on?"
This guide assumes you can convert odds to implied probability. If not, start with how to read CS2 betting odds.
What closing line value is
The closing line is the last price available before a match starts. By then the market has absorbed the most information it will get before play: lineups, stand-ins, map pool news and, above all, money from bettors who price matches well. On busy markets the closing price is usually the most accurate estimate of the true chance that the market produces.
Closing line value is the gap between the price you took and that closing price. If you bet a team at 2.10 and it closes at 1.87, the market moved toward your view after you bet, and you hold a price nobody can get any more. Do that on most of your bets and you are very likely finding value, even through a losing run. Betting analyst Joseph Buchdahl puts it simply: the ratio of your price to the fair closing price is a reliable estimate of your expected advantage.
The two CLV formulas
1. Price-based CLV (quick)
CLV = (your odds ÷ closing odds) - 1
Easy to compute, but the closing odds still include the bookmaker margin, so this version flatters you. It tells you that you beat the market, not by how much in expected value.
2. No-vig CLV (better)
First strip the margin from the closing prices of both sides:
- Implied probability of each side = 1 ÷ its closing odds.
- Fair closing probability of your side = its implied probability ÷ the sum of both implied probabilities.
Then:
No-vig CLV = (your odds × fair closing probability) - 1
This is your expected return per unit if the fair closing price is the true probability. You can also express CLV in probability points: fair closing probability minus the implied probability of the price you took. The no-vig and hold calculator does the margin removal for you.
Worked CS2 examples
Example 1: you beat the close
You take Team A at 2.10 in a best-of-three. By match start the book shows Team A 1.87 and Team B 1.95.
| Price | Odds | Implied |
|---|---|---|
| Your price on Team A | 2.10 | 47.6% |
| Team A at close | 1.87 | 53.5% |
| Team B at close | 1.95 | 51.3% |
| Closing total | 104.8% | |
| Team A fair (no-vig) close | 1.96 | 51.0% |
- Price-based CLV: 2.10 ÷ 1.87 - 1 = +12.3%.
- Fair closing probability: 53.5 ÷ 104.8 = 51.0%, a fair price of about 1.96.
- No-vig CLV: 2.10 × 0.510 - 1 = +7.2% per unit.
- In probability points: 51.0% - 47.6% = +3.4 points.
The quick formula says +12.3%, the honest one says about +7%. Both say this was a good bet, whatever the result.
Example 2: the line moves against you
You take the favorite at 1.65. It closes at 1.72, with the underdog at 2.12.
- Price-based CLV: 1.65 ÷ 1.72 - 1 = -4.1%.
- Implied at close: 58.1% and 47.2%, a total of 105.3%.
- Fair closing probability of the favorite: 58.1 ÷ 105.3 = 55.2%, a fair price of about 1.81.
- No-vig CLV: 1.65 × 0.552 - 1 = -8.9% per unit.
Even if the favorite wins, this was a poor price. The market drifted away from your side, and the fair close suggests you paid well over the odds for the outcome. One bet like this means nothing. A record full of them is a warning.
Example 3: Polymarket
You buy shares in Team X at 44 cents. Just before the scheduled start, the market trades at 50 cents.
- Your price as decimal odds: 1 ÷ 0.44 = 2.27.
- CLV before fees: 0.50 ÷ 0.44 - 1 = +13.6%.
- Fees: Polymarket charges takers a fee of shares × fee rate × p × (1 - p), and its help center lists a 0.05 rate for sports. For 100 shares at 0.44 that is 100 × 0.05 × 0.44 × 0.56 = about $1.23, so the 100 shares cost $45.23 in total, an effective price of 100 ÷ 45.23 = 2.21.
- CLV after fees: 0.50 × 2.21 - 1 = +10.5%.
Prediction market prices on the two sides of a match add up to roughly 100%, so there is little margin to remove. The spread and the fee do the same job instead, which is why you should count them. Limit orders that add liquidity are not charged the taker fee. The odds edge calculator turns any price and probability estimate into expected value.
How to collect closing prices
- Sportsbooks: note both sides of the match winner market as close to the start as you can, ideally from the sharpest, highest-volume book you can see. Use the same book every time so the benchmark is consistent.
- Polymarket: take the last trade or, better, the midpoint of the best bid and ask just before the scheduled start. Polymarket's help center says that in sports markets, open limit orders are cancelled when the game begins, and warns that start times can shift. Write down the time of your snapshot.
- Delayed starts: CS2 matches often start late when the previous series runs long. Use the price at the real start, not the scheduled one, when you can.
- Your own price: log the odds you actually got, after any fee, not the odds you saw a minute earlier.
Why CLV tells you more, sooner
A bet at odds of 2.00 either wins 1 unit or loses 1 unit, so each result swings by about 1 unit. The uncertainty in your average ROI after n bets is roughly 1 ÷ √n:
- 100 bets: 1 ÷ 10 = 0.10, so a 95% range of about ±20 points of ROI.
- 400 bets: 1 ÷ 20 = 0.05, about ±10 points.
CLV per bet moves far less. Suppose your no-vig CLV numbers bounce around with a spread of about 5 points from bet to bet (check your own; this figure is only for illustration). After 100 bets the uncertainty in the average is 0.05 ÷ 10 = 0.005, or half a point. An average CLV of +2% would then sit four standard errors above zero, while an ROI of +2% over the same 100 bets would be lost inside a ±20 point range.
That is the whole case for CLV. It does not replace results, because the closing line is not perfect and you still have to be paid at the end. But it lets you judge a process, or a tipster, in a few hundred bets rather than a few thousand. Our pick process page shows the sample-size arithmetic for ROI in more detail.
Limits in thin CS2 markets
The case for CLV rests on the closing line being accurate. In CS2 that holds best for big tier 1 matches and gets weaker further down:
- Thin liquidity. In tier 2 and tier 3 matches, a single bet or trade can move the price. A "close" set by one order says little about the true chance.
- Wide spreads and high margins. The wider the gap between the two sides, the less precise the fair price you back out of it.
- Margin assumptions. The simple no-vig method spreads the margin in proportion to each side. If a book loads more of its margin onto one side, the fair price you back out for that side will be off.
- Late news. A stand-in or a changed map pool announced minutes before the start can move the price after the moment you recorded as the close.
- Soft benchmarks. Beating the closing price at one recreational book proves less than beating a high-volume market.
So treat CLV on small CS2 events as a rough signal. Weight it toward matches with real volume, and keep checking the actual results alongside it.
How to track it
For each bet, log six things: date, match, side, the odds you got, both closing prices, and the result. Then:
- Compute no-vig CLV for each bet.
- Average it across all bets, and separately for tier 1 and lower tiers.
- Compare it with your actual ROI over time.
If your average CLV is clearly positive across a few hundred bets, a losing run is more likely bad luck than a bad process. If it is negative, a winning run is more likely good luck. The ledger ROI calculator handles the results side, and the same checks are a good way to judge any CS2 tipster who posts odds.