Learn
The math behind every bet.
Plain guides to what a price implies, what the sportsbook keeps, when a bet is worth making and how much to stake. The ideas hold for every sport; the NFL guides cover what football adds.
01Basics
The bets, and how to read their prices.
Moneylines, spreads and totals, the three bets every game offers, and the three ways a price is written.
Calculators for this
- 01Moneyline betsWhat a moneyline bet is, how favorite and underdog prices read, and what they imply.
- 02Point spreadsHow a point spread works, what covering means, and why the price on each side matters.
- 03Totals (over/under)How a total works, how over and under are priced, and what moves a total.
- 04How to read oddsAmerican, decimal and fractional odds, and how to move between them.
02The math
What a price is telling you.
What a price says about an outcome's chance, what the sportsbook keeps, and when a bet is worth making.
Calculators for this
- 01Implied probabilityThe chance a price implies, and why a market's chances add up to more than 100%.
- 02Vig and no-vig pricesThe sportsbook's margin, how to take it out, and what a fair price is.
- 03Expected value and edgeWhat expected value means for a bet, how edge is measured, and why it is an estimate.
- 04Closing line value (CLV)Why the closing price is a useful yardstick, and how to compare yours with it.
03Bankroll
Stake for the long run.
How much to stake, how to stay in the game through a losing run, and why parlays cost more than they look.
Calculators for this
- 01Kelly sizing and unitsWhat the Kelly criterion says, why fractions of it are safer, and how units work.
- 02Bankroll managementA bankroll, unit sizes, stake caps and loss limits: the rules that keep betting affordable.
- 03Parlays and correlationHow parlay prices are built, why same-game legs are not independent, and what that does to the math.
04NFL
What football adds.
What is particular to football: key numbers, player props, weather, rest and the rhythm of the week.
Calculators for this
- 01NFL key numbersWhy 3 and 7 matter so much in NFL spreads, and how key numbers change a half point's worth.
- 02NFL player propsThe common NFL player prop markets, and what to check before betting one.
- 03NFL weather and windHow wind, rain, snow and cold affect NFL games, and when the forecast matters.
- 04NFL rest and travelShort weeks, byes, long trips and time zones: what the schedule can and cannot tell you.
- 05The NFL week and the playoffsHow an NFL week runs, when lines open and move, and how the playoffs work.
05Glossary
All termsEvery term, in plain words.
44 betting terms, from American odds to the vig, each with a short definition, an example where one helps, and the guide or calculator that goes further.
Open the glossary- VigThe sportsbook's margin, built into its prices.
- No-vig priceA price with the sportsbook's margin taken out: the market's own estimate of each outcome's chance.
- Expected valueWhat a bet wins or loses on average if your win chance is right: the win chance times the profit, less the lose chance times the stake.
- Closing line valueHow much better your price was than the closing line, the market's last price before the game starts.
- Key numbersThe final margins NFL games land on most often: 3 and 7 above all, since scoring comes in field goals and touchdowns.
- UnitA standard stake, often 1% to 2% of the bankroll.
Put the math to work.
Unitley shows the no-vig price and expected value for every NFL game it covers, and sizes stakes to your own bankroll: in your own Claude, in another AI agent, or in the web app on your own key. Analysis, never a guarantee.