How to Calculate Closing Line Value (CLV) in Sports Betting

Closing line value (CLV) measures how the odds you bet compare with the final widely available market price before an event starts. If you consistently place a bet at better odds than the closing line, you are likely beating the market, even when individual results include short-term variance.

The simplest decimal-odds formula is:

CLV = (your betting odds ÷ closing odds − 1) × 100

A positive percentage means your price was better than the closing price. A negative percentage means the market moved against your selection after you placed the bet.

How to calculate CLV with decimal odds

Suppose you back a football team at decimal odds of 2.10, and the best comparable closing price is 1.90.

• Your odds: 2.10
• Closing odds: 1.90
• Calculation: (2.10 ÷ 1.90 − 1) × 100
• Closing line value: 10.53%

The market shortened the selection from 2.10 to 1.90, so your bet was placed at a more attractive price. The eventual match result does not change this CLV calculation. A losing bet can have positive CLV, while a winning bet can have negative CLV.

Calculating CLV with American odds

American odds should be converted to decimal odds before applying the basic CLV formula. For positive American odds, use:

Decimal odds = 1 + (American odds ÷ 100)

For negative American odds, use:

Decimal odds = 1 + (100 ÷ absolute value of American odds)

For example, a bet placed at +120 converts to 2.20 decimal odds. If the market closes at +105, the closing price converts to 2.05.

• Your decimal odds: 2.20
• Closing decimal odds: 2.05
• CLV: (2.20 ÷ 2.05 − 1) × 100
• Result: 7.32%

For a favourite, the same process applies. Odds of -110 equal approximately 1.9091 in decimal format. If the closing price is -125, or 1.80 decimal, the CLV is approximately 6.06%.

Using implied probability to measure closing line value

Some bettors prefer to express CLV as a change in implied probability. For decimal odds, implied probability is:

Implied probability = 1 ÷ decimal odds

The probability-based formula is:

CLV = (closing implied probability ÷ your implied probability − 1) × 100

Using the 2.10 and 1.90 example:

• Your implied probability: 1 ÷ 2.10 = 47.62%
• Closing implied probability: 1 ÷ 1.90 = 52.63%
• CLV: (52.63% ÷ 47.62% − 1) × 100
• Result: 10.53%

This method produces the same direction and percentage as the decimal-odds comparison when comparing one price with another. It also makes the market movement easier to understand: the closing market assigned a higher implied chance to the outcome than the price available when you bet.

How to remove bookmaker margin from closing odds

Raw implied probabilities include the bookmaker’s margin, also called the overround or vig. For a more accurate estimate of market movement, remove the margin from all outcomes in the market.

For a two-outcome market, first convert both closing prices into implied probabilities:

• Outcome A: 1 ÷ its closing decimal odds
• Outcome B: 1 ÷ its closing decimal odds

Add those probabilities together. Then divide each individual probability by the total:

No-vig probability = individual implied probability ÷ total implied probability

For example, closing odds of 1.90 and 1.90 produce raw implied probabilities of 52.63% and 52.63%, or 105.26% combined. After removing the margin, each side has a no-vig probability of 50%.

No-vig CLV is particularly useful when comparing prices across different sportsbooks or analysing markets with varying levels of bookmaker margin. In three-way football markets and other multi-outcome betting markets, include every outcome when calculating the total implied probability.

Which closing line should you use?

The closing line should represent the final price available in the same market immediately before the event begins. Use the same bet type, handicap, total, and settlement rules as your original wager.

Useful comparisons include:

• The final price at the sportsbook where you placed the bet.
• A market consensus closing price from several reputable sportsbooks.
• The sharpest widely available price, if your aim is to measure market efficiency.

Do not compare a full-game spread with a first-half spread, or a moneyline with a draw-no-bet market. Small differences in market definition can make the CLV result misleading. Record the timestamp, bet type, odds format, stake, and closing price so the comparison can be checked later.

How to track CLV over a betting sample

One bet does not show whether your prices are strong. Track a meaningful sample in a spreadsheet or betting log. Useful columns include the event, market, selection, opening odds, odds taken, closing odds, stake, result, and CLV percentage.

You can calculate average CLV by adding the individual CLV percentages and dividing by the number of settled or recorded bets. A stake-weighted version gives more influence to larger wagers:

Weighted average CLV = total CLV contribution ÷ total stake

Keep the measurement consistent. Mixing different closing-line sources, including only successful bets, or recording closing prices after the event starts can distort the results. CLV is a process metric, not a guarantee of profit, and a positive average can coexist with a losing short-term record.

Common mistakes when calculating CLV

• Using the result instead of the closing price: CLV measures price movement, not whether the selection won.
• Comparing different markets: The original wager and closing wager must have identical terms.
• Ignoring odds format: Convert American or fractional odds consistently before applying the formula.
• Using an unreliable closing timestamp: Prices can change rapidly near the start time.
• Comparing only one sportsbook: A consensus closing line can provide a more representative market benchmark.
• Overreacting to a small sample: Variance affects both results and line movement, so evaluate CLV across many bets.

Use CLV as one way to assess your betting decisions, alongside expected value, price shopping, record keeping, and sensible bankroll limits. Only bet money you can afford to lose and follow the rules that apply where you live.