OSOTOTO — the sharp bettor’s calculator toolkit
21 fast, private calculators for betting and casino math — odds, expected value, Kelly staking, arbitrage, house edge and more. Everything runs in your browser.
Explore calculators Read the guidesBetting calculators
Odds Converter
Convert decimal, fractional, American, Hong Kong & implied probability instantly.
Expected Value (EV)
Find the true EV, edge and ROI of a single bet.
Vig Remover / True Odds
Strip the bookmaker margin to reveal fair odds and true probability.
Parlay / Accumulator
Combine up to 20 legs into one payout with combined odds.
System Bet (Lucky 15/31/63)
Trixie, Yankee, Lucky 15/31/63 — full breakdown of combination bets.
Each-Way Calculator
Split win/place, apply place terms and see total return.
Closing Line Value (CLV)
Measure how much better your odds were than the closing line.
Advantage play calculators
Arbitrage (Surebet)
Guaranteed-profit staking across 2 or 3 bookmakers.
Dutching
Back multiple selections for equal profit whichever wins.
Matched Betting
Qualifying loss and free-bet profit with back/lay & exchange commission.
Hedge / Cash-Out
Lock in profit or cut losses by hedging the opposite side.
Back/Lay (Exchange)
Lay stake and liability for a betting-exchange position.
Bankroll & risk calculators
Kelly Criterion
Optimal stake size from your edge — full, half & quarter Kelly.
Risk of Ruin / Drawdown
Probability of losing your bankroll given edge, odds and bet size.
Session Budget
How long a bankroll lasts at a given bet size and pace.
Staking Plans Simulator
Simulate Martingale, Fibonacci, D’Alembert, flat — with a bankroll chart.
Casino & slots calculators
House Edge → Cost/Hour
Turn RTP and pace into an expected hourly cost.
Slot Variance Simulator
Monte-Carlo a slot session and see the outcome distribution.
Bonus Wagering
Total turnover, expected cost and EV of a casino bonus.
Roulette Odds
Payouts and true probabilities for every roulette bet (EU/US).
Poker Odds (Pot Odds & Outs)
Pot odds, outs-to-equity and call/fold guidance.
Learn & track
Guides
Plain-English explainers on bankroll, RTP, value betting and reading odds.
Glossary
18 betting & casino terms defined clearly.
Bet Tracker
Log bets, see ROI, strike rate and a P/L chart — stored only on your device.
OSOTOTO is an independent, free educational tool. We do not take bets or offer gambling. Please gamble responsibly — take the self-check or visit responsible gambling resources. 18+.
