How to Use

The basics

Sportsbooks build a margin (the vig or juice) into every price, so the implied probabilities of all sides add up to more than 100%. Devigging strips that margin out of a sharp book's line to estimate the true, "fair" chance of each outcome.

Compare that fair probability with the price your sportsbook is offering. If the sportsbook pays more than the fair price, the bet has positive expected value (+EV). The calculator then tells you how much to stake using the Kelly criterion.

To use it, enter the sharp market, enter the price you're getting, and press Calculate. You can leave every other field at its default.

Sharp Odds

The market from a sharp (low-margin, well-informed) book. Use American odds. Put / between the sides of one market, and put a comma between the legs of a parlay.

One-way lines: estimated juice

Some markets, such as player props and longshot alternates, only show one side. You can't devig a single price, so you supply an estimate of the market's total juice with a % sign: +300/10% means "+300, in a market that's about 10% overround."

• The % is required. A bare +300/10 is rejected because 10 isn't a real American price.
• The percentage is total overround: all sides' implied probabilities add up to 100% + X%. It is not the book's hold.
• Juice must be greater than 0% and no more than 50%. Decimals are fine: +300/10.5%.
• The fair value depends heavily on this guess. +300 at 5%, 10% and 20% juice gives fair odds of roughly +359, +451 and +1055. Results that use an estimate are labelled (est.).

Up to 12 legs. The Clear link empties both odds boxes.

Sportsbook Odds

The American odds you're actually getting, one price per leg, in the same order as the sharp legs. Separate legs with spaces or commas: +475 or +475, -105. A parlay's prices are multiplied together into one final price.

If your book already shows the combined parlay price, you can enter just that single number.

Boost (%)

A profit boost, as a whole number. Leave it blank for no boost. A 25% boost on +200 increases the profit by 25%, from 2.00 to 2.50, so the price becomes +250. Boosts apply to the winnings, not the stake, which is how most books calculate them.

Promo types

Tick one of these if the bet comes with a promo. Only one can be selected at a time, because books almost never let you stack these promo types.

Free Bet

You're placing a bonus bet, which doesn't return the stake when it wins. Instead of EV, the result shows FB%, the conversion rate: the expected cash you get back per dollar of free bet. For example, FB=72% means a $100 free bet is worth about $72. Higher is better. Bet sizing is hidden because the free bet carries no bankroll risk.

Risk-Free

Sometimes called "second chance" or bet insurance. If the bet loses, you get your stake back as a bonus bet. The EV includes that refund at your conversion rate.

Draw Breaker

If a leg ends in a draw, your stake comes back as a bonus bet. Enter the sharp market for those legs as 3-way, in Win/Draw/Loss order (e.g. +150/+240/+190), so the calculator can find the draw probability. Two-way and one-way (estimated-juice) legs count as having no draw.

Bet & Get

You receive a bonus bet just for placing the wager, win or lose. Its value at your conversion rate is added to the EV.

Free Bet Conversion %

What a $1 bonus bet is worth to you in cash, as a percentage. Leave it blank to use the default of 70%, which is a typical rate if you place bonus bets on longshots. It's used by Risk-Free, Draw Breaker and Bet & Get to value the bonus bet you might receive. Plain Free Bet mode doesn't use it, because there the conversion rate is the result.

Bet Title

Optional free text, such as "Lakers ML + Celtics -4.5" or "DK 30% NBA parlay boost". It becomes the heading on the results page and the first line of the copied result, which makes it easy to label picks you share.

Sharp

Which book the sharp odds came from. This is only a label: it appears as "Devigged to …" in the results and doesn't change any calculation. Pick Other to type a book name yourself.

Bankroll

The total amount you've set aside for betting, in dollars. It's used to turn Kelly percentages into dollar stakes and units. One unit is 1% of your bankroll. Your browser remembers the value for next time (it's never sent anywhere except with the calculation). The default is 10,000.

Devig Method

There's more than one reasonable way to remove the vig. The methods differ mostly in how they split the margin between favorites and longshots.

Multiplicative

Scales every side down by the same proportion. Simple, and it's the most common baseline.

Additive

Subtracts the same amount of probability from every side. This is harsher on longshots.

Power

Raises each probability to a power until they add up to 100%. It assumes books overcharge longshots, which tends to match real markets.

Probit

Shifts the probabilities on a bell-curve (normal) scale. Only available for 2-way markets.

Worst Case

Runs every method over the whole bet and shows the one with the lowest EV.

Worst Case (Per Leg) default

For each leg, picks whichever method gives that leg the lowest fair probability, then combines the legs. This is the most conservative choice and a sensible default: if a bet is +EV here, it's +EV under every method.

Show All Methods

Shows a separate result card for each method, so you can compare them.

Reading the results

EV / FB

Expected value as a percentage of your stake. EV=+5% means you'd expect to profit $5 per $100 wagered over the long run. In Free Bet mode this is the conversion rate instead (see above).

Fair Value

The devigged fair odds and the probability of the whole bet winning.

QK / EK

Quarter Kelly and Eighth Kelly. The Kelly criterion gives the stake that grows a bankroll fastest when your probabilities are exactly right. They never are, so most bettors stake a fraction of it. QK is shown in units and dollars, and EK in dollars.

Juice

The total vig across the sharp legs. The chip for each leg is green between 0% and 10%, and red otherwise. Very high juice makes the devig less reliable. Negative juice usually means a typo, such as a wrong sign, and you'll get a warning.

Copy

Copies a plain-text summary that's ready to paste into Discord or a group chat. It includes an Edit Devig link that reopens the calculator with all your inputs filled in.