Gambling Resources
Short, practical reference pages for converting odds, understanding probability, and using gambling math.
What you will find here
This section holds the practical tools. The guides elsewhere on Gambling101 explain why a bet is good or bad; these pages let you check the numbers yourself. Each one takes a few inputs you can find on a bet slip or a game’s info screen and turns them into a figure you can compare.
If you only use one, make it the house edge calculator. Most decisions in a casino come down to how much a game costs you on average, and that number is easy to miss when a payout looks big.
Calculators
- House edge calculator: enter an RTP, or a win probability and payout, and see what the casino keeps on average.
- Expected value (EV) calculator: the average win or loss per bet, with worked examples.
- All calculators: every tool on the site in one list.
Reference pages
- Implied probability explained: turn American, decimal or fractional odds into a percentage.
- Gambling glossary: short definitions for casino and sports betting terms.
- House edge by game: typical figures for common table games, video poker and slots in one table.
How to use them well
Treat every result as an average over many bets, not a forecast for tonight. A negative number means the bet costs you money over time even if it wins now and then. Pair the numbers with a budget: our setting limits guide shows how to pick one before you play.