Free Bet Value Calculator
What a stake-not-returned free bet is actually worth, and the lay odds that turn it into guaranteed cash.
This prices one stake-not-returned token at the two prices you type in, at the moment you type them, and says nothing about whether either price will still be there or how much of it either side will accept.
Converting it on an exchange
Guaranteed profit
$14.07
the same amount whichever side of the event wins
Held by the exchange
$45.93
$3.27 of balance per $1 locked in, for as long as the event runs
Lay stake
$14.35
to lay on the exchange, at the lay odds
Retention
70.3%
guaranteed, as a share of face value
Where the face value goes
- Kept, whichever side wins70.3%
- Spread and commission4.7%
- The stake you never get back25.0%
If the free bet wins
If the lay wins
Every price field reads an American price (+150). Switch the format above to enter prices the way your book quotes them, or open the odds converter to see one price in all of them.
Retention across back odds
This curve holds the lay price at 3% above the back price plus $0.02, so it describes odds in general rather than the two prices you entered above. It rises the whole way, reaching about 87% at odds +1100, which is where the chart stops and not where retention peaks. What rises with it is the liability the exchange holds while the event runs.
Written and reviewed by Alexander Korsager · last reviewed September 27, 2026 · corrections
The idea
What this tool shows
A free bet is almost never worth its face value. With a "stake not returned" (SNR) token you only ever collect the winnings, not the stake, so a $20 free bet at even money returns $20, not $40. Its real worth depends entirely on the odds you use it at and what you do with it.
If you lay the same selection on an exchange, you can convert the free bet into cash that is yours whichever way the event goes.The lay stake is the free bet times the back odds minus one, divided by the lay odds minus the commission. At close prices a token used somewhere around 4.0 to 6.0 keeps roughly 70–80% of its face value, and retention keeps climbing from there rather than turning over: what grows with the back price is the liability the exchange holds while the bet runs, not a point where the arithmetic stops paying.
If you simply place the free bet and hope, its expected value is your win probability times the potential winnings.At fair odds that works out to (odds − 1) / odds of the face value (about two-thirds at odds of 3.0) but with real variance attached.
FAQ
Questions players ask
Do longer back odds convert a free bet better?
Under this arithmetic, yes, and it does not turn over. Retention is (back odds − 1) × (1 − commission) ÷ (lay odds − commission), so as long as the lay price tracks the back price by a fixed rule, retention rises with the back odds the whole way. The chart's rule is 3% above the back price plus $0.02, and under it the curve climbs from 31.7% at odds of 1.50 to 87.2% at 12.00, where the chart stops rather than where the curve peaks. What grows alongside it is the money the exchange holds. Under that same rule, converting a $20 token at 4.00 ties up $45.73 of liability; the same token at 12.00 ties up $202.56, in a market that is usually thinner and wider than a fixed rule assumes. That is the real ceiling on this, and it is a limit on your exchange balance rather than on the retention percentage.
Why is retention not 100%?
Three things take a share, and the biggest one is not a fee. The stake you never get back costs the most: even at a perfect price, laying at exactly the back odds with no commission at all, a token converts to (odds − 1) ÷ odds of its face value, which is 75% at odds of 4.00. The exchange's spread and its commission take what is left. At the shipped 4.00 backed, 4.20 laid and 2% commission the figure is 70.3%, so of the 29.7% that goes missing, 25 points is the stake rule and under 5 points is friction.
Is using a free bet at very high odds a good idea?
For raw expected value it can be, and the outcome is almost always nothing: placed at 12.00 the token pays on roughly one attempt in twelve. Laying it off converts that lottery into an amount that lands whichever way the event goes, and the gap between the two figures is the friction rather than a view about which route suits you. One token's arithmetic is also not a strategy. Nothing on this page says how many offers an account will see, at what size either side will accept them, or for how long.
Methodology
How this is calculated
A stake-not-returned token pays the winnings only, so a winning free bet at decimal odds B returns free × (B − 1) and the stake stays with the bookmaker.
Laying the same selection for L on an exchange risks L × (lay − 1) to win L × (1 − commission), and the two branches of the event are free × (B − 1) − L × (lay − 1) if the back wins and L × (1 − commission) if the lay wins. Setting them equal gives the lay stake the panel prints: free × (B − 1) ÷ (lay − commission).
Put that back into either branch and the token size cancels out, so retention is (B − 1) × (1 − commission) ÷ (lay − commission) and the same percentage holds for a $5 token and a $500 one.
Just place it prices the other route from the reader's own number rather than the bookmaker's: the token pays free × (B − 1) with probability 1 ÷ your fair odds and nothing otherwise, so its expected value is that product, which at fair odds collapses to (B − 1) ÷ B of face value.
At the shipped 4.00 backed, 4.20 laid and 2% commission the panel locks in $14.07 on a $20 token, 70.3%, against $15.00 of expected value for placing it at fair odds of 4.00.
Common misreadings4
- The locked-in figure is a figure, not an outcome, until both bets are on. Between placing the free bet and getting the lay matched you are holding a single one-way bet at a price you chose for a pair.
- Retention is the value of one token converted once. It is not a rate of return on the bankroll that funds the liability, and multiplying it by a number of offers per month produces an income figure this page does not support.
- Placing does not always price higher than laying off, even though it does at the shipped defaults. The two are the same trade until friction: at fair odds a placed token is worth exactly what a frictionless lay-off would keep, so the comparison turns on whose margin is larger, the exchange's or the bookmaker's in the price you are being offered. Placing prices higher only while your fair odds are shorter than (lay odds − commission) ÷ (1 − commission), which is 4.27 at the panel's shipped 4.20 and 2%. Estimate the same selection at 4.50 instead and the placed value falls to 66.7% while the lay-off still keeps 70.3%.
- A higher retention percentage is not a larger amount of money against the same exchange balance. Converting at longer odds keeps more of the token and ties up several times as much for the same event, and the two move together.
Assumptions6
- The token is stake not returned. A free bet whose stake comes back with the winnings, or a bonus credited as withdrawable cash, is worth more than any figure here and is priced by different arithmetic.
- The lay is matched in full, at the price shown, in one go. Everything on the panel is the arithmetic of a completed pair of bets.
- Every price field reads whichever format the odds format control is set to, and only that one. The control exists, rather than a field that takes anything, because 150 is a real decimal price as well as the American price +150: a field reading both would have to guess which you meant on exactly the input where guessing wrong is invisible, since a wrong price of that kind still prints a complete and correctly formatted panel. A price that does not read in the selected format shows nothing rather than a figure, and the page names the format it would read in when there is one. Switching the format rewrites the prices already entered, so a field never holds a number in a format the page is no longer reading. The retention chart's axis follows the same switch. The CSV behind it stays in decimal whichever format is showing, and says so in its own header, because a file read away from this page cannot see which control was set.
- Commission is charged on the winnings of the lay at the rate you enter. An exchange that charges on net market winnings instead, or that applies a loyalty discount, settles at a different number.
- Both bets settle on the same result under the same rules. A void event, a non-runner, a dead heat or a deduction can settle one side and not the other, and a pair that settles apart was never a pair.
- Nothing is taken off the token before it pays. A free bet capped below its face value, restricted to a minimum price, or credited at a boosted price the bookmaker will not honor at size, pays less than free × (B − 1).
Limits7
- The chart and the panel answer slightly different questions, and the chart says so rather than reading your inputs. It sets the lay price at 3% above each back price plus $0.02, so it is a claim about odds in general rather than about the two prices above it. At the shipped 4.00 the panel prints 70.3% from a 4.20 lay and the chart sits at 71.4% from its own assumed 4.14, which is 4.00 × 1.03 + 0.02. The panel is the one using your prices, and that one rule is every other point on the curve, so you can rebuild any of it without the page.
- The curve rises across the whole range it is drawn over, so its high point is the right-hand edge, 12.00. That is the end of the chart, not a maximum the arithmetic produces. Retention approaches (1 − commission) ÷ 1.03 as the odds get longer and never reaches it, which is 95.1% at the shipped 2% commission against the 87.2% the right-hand edge actually prints.
- The spread rule is the assumption doing the most work at long odds, and it is closest to a flat percentage there rather than at the short end. The two cents is 1.3% of a 1.50 price and 0.2% of a 12.00 one, so the curve models a 1.50 as laid 4.3% over the back price and a 12.00 as laid 3.2% over it. Real exchange prices widen in absolute terms and thin out as the price gets longer, so the right-hand end of the curve is the most optimistic part of it.
- Liability is not shown on the chart and it is what limits this in practice. The exchange holds lay stake × (lay − 1) for the whole event. Under the chart's own spread rule that is $45.73 against a $20 token at 4.00 and $202.56 at 12.00, so the sixteen points of retention between those two odds cost four and a half times the exchange balance. The panel's shipped 4.20 lay is a third figure again, $45.93, because it is a different price from the one the chart assumes.
- Stakes are priced to the cent. Rounding a lay stake down leaves the back branch paying less than the lay branch, and the amount you actually keep is then the smaller of the two, not the figure printed.
- Every retention figure here is the value of a lay you can actually get on, so a two-sided market with a stated commission is the thing the whole page rests on rather than one input among several. Having one is an ordinary assumption in the UK and Australia and an uneven one in the US, where a lay side is more often quoted by a federally regulated prediction market than by a state-licensed sportsbook exchange. With no lay side there is no conversion to price at all, and the token is worth whatever the single bet returns, which is the Just place it figure rather than any retention percentage above it. Check what is open to you before treating a lay stake on this page as an order.
- Just place it is priced off the fair odds you supply. It is your estimate of the true probability, and the expected value moves with it directly: nothing on this page checks it or derives it for you.
Evidence
The model is an identity rather than a source: with a stake-not-returned token the two branches are algebra on the payout rule, so there is nothing here transcribed from a table that could be out of date. math.test.ts pins it from the other direction, hand-deriving retention as (B − 1)(1 − commission) ÷ (lay − commission) without computing a lay stake and checking it against the implementation across five real price pairs; it pins the frictionless case at exactly (odds − 1) ÷ odds, that the two modes agree there, that retention does not move with the token size, that the curve rises at every one of the 42 steps between its 43 points, and that the 87% the chart prints is its right-hand endpoint at odds of 12.00.
What none of that can check is whether the price you typed is one you will actually get matched at.
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