CLV betting: measuring the price you took against the close
- The vig, the amount over 100 (%)
- 4.76
- First side, implied probability as priced (%)
- 52.38
- Other side, implied probability as priced (%)
- 52.38
Every figure on this site comes out of the prices you type and the arithmetic printed beside them. There is no feed, no price of our own and no third-party data: the site holds no odds at all, only the method for reading the ones you already have. Conversions are exact, not approximations, and the American-to-probability step is written out on each page so you can check it by hand.
Closing line value is one subtraction: the probability your price implied, against the probability the closing price implied, both with the margin taken out. It is a measurement of the price you got and not a prediction of anything, which is why it can be worked out precisely and why it is the one figure in this subject that is entirely arithmetic. This page sets out how to compute it honestly, and what it cannot tell you.
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Take the vig out of both prices, not one
The number people usually compare is a raw opening price against a raw closing price, and both carry a margin that is rarely the same size. Strip each two-sided market to its fair probabilities first; a market that tightened between open and close will otherwise show a value that is entirely the margin moving.
Subtract the two fair probabilities
Your fair probability minus the closing fair probability, in percentage points, is the closing line value. A positive number means the price you took was longer than the price the market settled on, for the same outcome. That is the whole definition, and it is worth writing it down in points rather than in odds, because points are comparable across markets.
Convert the difference into what it was worth
Points are not money. Feed your price and the closing fair probability into the expected value calculator to see what the difference was worth per unit staked, which is almost always a much smaller figure than the gap in points suggests. Doing this for one price is arithmetic; doing it across a record is a measurement of a process.
Be clear about what it does not say
Closing line value measures the price you obtained against the price the market reached. It is not a result, it does not become one, and a record of positive closing line value is not income and must not be read as any kind of forecast. It says one thing: you were on the long side of where the market ended up.
CLV betting and closing line value: what people ask about the arithmetic
What does CLV betting actually mean?
It is shorthand for comparing the price you took with the closing price on the same outcome, both converted to probabilities and stripped of margin. The comparison is a measurement of the price, not of the outcome, and it is complete before the event even happens.
Why take the vig out before comparing?
Because the margin is part of the posted number and it changes between open and close. Comparing raw prices measures the margin's movement as well as the market's, and on a market that tightened, most of what looks like value is the charge shrinking.
Is positive closing line value a guarantee of anything?
No. It is a description of one price against another price. It makes no claim about any outcome, about a run of outcomes, or about money, and this site makes no such claim anywhere.
How do I express it: in odds or in percentage points?
In percentage points of fair probability. Odds are a non-linear scale, so a ten-point move at short prices and a ten-point move at long prices look wildly different in odds and are the same size in probability, which is what makes points the comparable unit.