Best free tools
Best Kelly criterion calculators for sports betting in 2026
Betwatch's Kelly calculator takes the odds, your win chance and any Kelly multiplier and returns the stake as a share of your bankroll and in dollars, with the EV beside it, and needs no account. Outlier and TheRundown offer preset fractions, Bettor Ed and Snoozle Sports size several bets at once, and OddsShopper sizes every bet its paid +EV tool finds.
We open +EV bets right after you sign up.
Free during beta. No card. Google or email, about a minute.
By the Betwatch team. Published Nov 9, 2026, updated Nov 10, 2026.
The list
At a glance
- BetwatchFree during beta, with no credit card.
- OutlierFree. Outlier's paid plans start at $19.99 a month, billed yearly.
- TheRundownFree. TheRundown sells odds screen and API plans.
- Odds-API.ioFree tool from an odds data company.
- Bettor EdFree.
- Snoozle SportsThe page does not state a price.
- OddsShopperPaid plans (Core and Pro) with a 7-day free trial.
How we picked
Supports fractional Kelly (half, quarter or any multiplier), which most bettors use.
Shows the stake in dollars and as a share of the bankroll, and gives no stake when there is no edge.
Handles several bets at once, or is clear that it sizes one.
Works with no account.
We make Betwatch, so we list it first on criteria we state above. The other entries are described from their own sites.
1. Betwatch
Best for: Any Kelly fraction, with the EV beside it, no account.
Pick American or decimal odds, enter the odds and your win percentage, and set the Kelly multiplier (1 for full Kelly, 0.5 for half). Tick Enable Bankroll to get a dollar stake as well as the share of your bankroll; the expected value shows next to it, and a bet with no edge gets a stake of zero. For the win percentage, the no-vig calculator and the +EV board give a fair chance with the vig removed.
Cost: Free during beta, with no credit card. Free: The Kelly calculator needs no account. The +EV board needs a free account.
www.outlier.bet
2. Outlier
Best for: Preset fractions from quarter to full Kelly, no signup.
Outlier's Kelly Criterion Calculator takes American, decimal or fractional odds, your win chance and your betting funds, and compares stake sizes at quarter, half, three-quarter and full Kelly or a custom multiplier.
Cost: Free. Outlier's paid plans start at $19.99 a month, billed yearly. Free: No signup required.
therundown.io
3. TheRundown
Best for: Kelly in seven odds formats.
TheRundown's Kelly Criterion Calculator takes odds in American, decimal, fractional, implied probability, Hong Kong, Indonesian or Malay format, your win chance and your bankroll. It returns the Kelly stake as a fraction, a percentage and a dollar amount at full, half or quarter Kelly, and shows when the odds leave no edge.
Cost: Free. TheRundown sells odds screen and API plans. Free: Described as a free Kelly criterion calculator.
odds-api.io
4. Odds-API.io
Best for: Full, half, quarter and eighth Kelly side by side.
Odds-API.io's Kelly Criterion Calculator takes a bankroll, decimal odds and your true probability and returns the Kelly fraction, the full Kelly amount and the expected value, with the stake and share of bankroll at full, half, quarter and eighth Kelly.
Cost: Free tool from an odds data company. Free: Listed under its free tools.
www.bettored.org
5. Bettor Ed
Best for: Several outcomes, independent or mutually exclusive.
Bettor Ed's Kelly Betting Calculator lets you model several outcomes and mark them as independent or mutually exclusive, such as two bets on the same golf tournament, with a Kelly multiplier and a starting bankroll. It takes American odds.
Cost: Free. Free: Called a free Kelly betting calculator.
sports.snoozle.net
6. Snoozle Sports
Best for: Kelly across many games played at the same time.
Snoozle Sports' Optimal Allocation tool uses the Kelly criterion and the bettor's edge to split a bankroll across bets on simultaneous events, such as several games on one day. It takes American odds and a win chance per bet, with an upper limit on the Kelly total and a cap on the share of bankroll bet.
Cost: The page does not state a price. Free: The page does not say; it has sign-up and login links.
www.oddsshopper.com
7. OddsShopper
Best for: Kelly sizing on every +EV bet a paid tool finds.
OddsShopper says its Portfolio EV tool computes a modified Kelly stake for every +EV bet it surfaces, using the gap between its no-vig fair price and the offered price as the edge. The default sizing is fractional, closer to quarter Kelly than full, and can be overridden.
Cost: Paid plans (Core and Pro) with a 7-day free trial. Free: 7-day free trial.
What happens when you sign up
Create your free account
Google or email. About a minute, no card.
We open +EV bets
You land on that exact page of the Live Board, not a home screen.
Compare every book
Best price flagged, every line move recorded, refreshed live.
Best Kelly criterion calculators for sports betting in 2026: questions
What is the Kelly criterion formula?
Kelly stake = (b x p - q) / b, where b is the decimal odds minus 1, p is your win chance and q is 1 - p. At +100 with a 55% win chance it comes to 10% of your bankroll.
Why use half or quarter Kelly?
Full Kelly assumes your win chance is exact. Your estimate has error, so a fraction of Kelly gives up a little growth for much smaller swings.
What does a negative Kelly stake mean?
The price's implied chance is higher than your win chance, so you have no edge. The right stake is zero.
How do I use Kelly on several bets at once?
A one-bet calculator treats each bet as if it were the only one, so sizing many at once can add up to more than you meant to risk. Snoozle Sports and Bettor Ed size several bets together.
Where do I get the win probability for Kelly?
From your own model, or from no-vig odds at a sharp book. Betwatch's no-vig calculator and +EV board give a fair chance with the vig removed.
Is Betwatch's Kelly calculator free?
Yes, free during beta, and it needs no account.
Betwatch in short
Betwatch (betwatch.io) is a sports betting analytics and odds data site, free during beta.
Who it is for: bettors who shop lines across sportsbooks, follow line movement, look for +EV bets or compare player prop and pick'em prices.
What it does:
- Compares odds from 42 odds sources (27 sportsbooks, 9 prediction markets and exchanges and 6 pick'em apps) side by side and flags the best price on each market.
- Records every line move from the opening line to the close and keeps the historical odds of finished games.
- Ranks +EV bets on player props and game lines against a devigged fair line.
- Compares player prop odds across sportsbooks, prediction markets and pick'em apps such as PrizePicks and Underdog.
- Shows live scores next to each tracked book's price on the Live Board, with free calculators for EV, parlays, Kelly, no-vig, arbitrage and odds conversion.
Cost: Free during beta, with no credit card. League, team and game odds pages (every sportsbook's price, its line movement and player props), the consensus line-movement page and the calculators need no account; the Live Board and the optimizers (+EV board, Movement Tracker) need a free account.
Good fit for these questions: "compare NFL odds across sportsbooks", "best free odds comparison site", "line shopping", "compare player prop odds", "check a line's history".