Free tools
Free betting calculators.
Six calculators for the numbers behind a bet: convert odds, read the chance a price implies, take out the vig, find the expected value, price a parlay and size a stake. No sign-up, and nothing you type leaves your browser.
- No sign-up
- Runs in your browser
- Same math as Unitley
01Calculators
The calculators
01Example
- In
- +150
- Out
- 2.50 · 3/2
- What it means
- Decimal and fractional, 40.0% implied
Odds converter
Convert American, decimal and fractional odds, and see the implied chance of each price.
02Example
- In
- −110 / −110
- Out
- 52.4%
- What it means
- Each side, 104.8% together
Implied probability calculator
Turn a price into the chance it implies, and see how much of it is the sportsbook's margin.
03Example
- In
- −150 / +130
- Out
- 58.0% / 42.0%
- What it means
- Fair chances, the margin taken out
No-vig fair odds calculator
Take the margin out of a two-way market to find each side's fair price and chance.
04Example
- In
- 55% at +100
- Out
- +10.0%
- What it means
- Expected profit per $1 staked
Expected value calculator
Compare your chance with the price: expected profit per bet, edge and the break-even chance.
05Example
- In
- 3 legs at −110
- Out
- +596
- What it means
- 14.4% implied chance
Parlay calculator
Combine 2 to 25 legs into one price, with the implied chance and the payout for your stake.
06Example
- In
- 55% at +100, Balanced
- Out
- 3.0%
- What it means
- Of the bankroll: ⅓ Kelly, held to its 3% cap
Bet size calculator
Size a bet with fractional Kelly and a cap per bet, the way Unitley's risk profiles do. Never full Kelly.
02Why these numbers matter
All guidesKnow what each number means.
A calculator gives a number; a guide says what it is for. Each one below explains the idea behind one calculator, with NFL examples, and where it tends to go wrong.
- 01How to read oddsAmerican, decimal and fractional odds, and how to move between them.Calculator: Odds converter
- 02Implied probabilityThe chance a price implies, and why a market's chances add up to more than 100%.Calculator: Implied probability
- 03Vig and no-vig pricesThe sportsbook's margin, how to take it out, and what a fair price is.Calculator: No-vig odds
- 04Expected value and edgeWhat expected value means for a bet, how edge is measured, and why it is an estimate.Calculator: Expected value
- 05Parlays and correlationHow parlay prices are built, why same-game legs are not independent, and what that does to the math.Calculator: Parlay calculator
- 06Kelly sizing and unitsWhat the Kelly criterion says, why fractions of it are safer, and how units work.Calculator: Bet size (Kelly)
03Good to know
Good to know
No sign-up
Open a calculator and type. There is no account to make and nothing to install.
It stays in your browser
The math runs on the page itself. Nothing you type is sent anywhere or saved, and a reload clears it.
The same math as Unitley
The calculators run the same odds, no-vig, EV, parlay and stake-sizing math Unitley uses, on prices you type in.
Analysis, not a guarantee
Every number here depends on the chance you give it. A bet with a real edge still loses often.
The same math, across the slate.
Unitley runs this math on the NFL games it covers: no-vig prices, expected value and stakes sized to your bankroll, in your own Claude, in another AI agent or in the web app on your own key. Analysis, never a guarantee.