Point Spread Calculator: Spread to Win Chance
A point spread is the expected margin of victory. If results are bell-shaped around it, the favorite's chance to win outright is the normal curve's value at spread ÷ standard deviation. A 3-point favorite with a standard deviation of 13 wins about 59% of the time.
Key facts
- The difference between two teams' scores is often modeled with a normal distribution.
- Under that model the favorite's win probability is the normal CDF of spread ÷ standard deviation.
- Moneyline-to-spread conversion uses the inverse of that function.
Spreads and moneylines describe the same game two ways. If you know how widely results spread, you can translate between them: how likely is a 3-point favorite to win outright, or what spread does a -150 moneyline imply? The model is simple and the standard deviation is yours to choose. It runs in your browser, sends nothing anywhere and forgets your numbers when you close the page.
Point spread calculator
Turn on JavaScript to use the calculator. The worked example below shows the same math by hand.
What you enter and what you get
You enter
- Direction: a number.
- Spread of results (standard deviation): An assumption you set. Check it against real results for your sport.
- Favorite's spread (points): Enter 3.5 for a -3.5 favorite.
- Favorite's moneyline: For example -150.
- Underdog's moneyline (optional): Adds vig removal.
You get
- Favorite wins outright
- Underdog wins outright
- Fair moneyline, favorite
- Fair moneyline, underdog
- Spread used
How the calculator works
- Assume the margin follows a bell curve centered on the spread.
- Favorite's win chance = the curve's value at spread ÷ standard deviation.
- Fair moneyline = 1 ÷ win chance, shown as American odds.
- To go backwards, find how many standard deviations a win chance corresponds to and multiply by the standard deviation.
A worked example
A 3.5-point favorite with a standard deviation of 13 points.
Spread to win chance
| Item | Result |
|---|---|
| Favorite wins outright | 60.6% |
| Underdog wins outright | 39.4% |
| Fair moneyline, favorite | -154 |
| Fair moneyline, underdog | +154 |
| Spread used | -3.5 |
What the calculator leaves out
- Real margins are lumpier than a bell curve, especially around common final margins.
- The standard deviation is an assumption, and the answers scale with it.
- Moneylines carry vig, so a raw moneyline overstates the win chance unless you enter both sides.
How we checked it
Before it went on the page we checked it against cases worked by hand: a -3 spread with a 13-point spread of outcomes has to land near 59%, and running it backwards, 59.1% has to give about -3. The calculator is also run against thousands of odd entries such as blanks, zeros and huge numbers, so a bad entry shows a plain prompt and never a wrong number. The worked example above comes from the same code the calculator runs.
At a sweepstakes sportsbook
Where a sweepstakes sportsbook offers spreads, the same relationship holds between its spread and moneyline prices, which makes it a quick check on whether the two are priced consistently. How we make our guides explains how we handle models and estimates.
Betting math is not betting advice. Only play with money you can afford to lose, and if gambling stops being fun, call or text 1-800-GAMBLER.
Frequently asked questions
What standard deviation should I use?
Take it from past results for your sport and league, and test a few values to see how much the answer moves.
Does a bigger spread always mean a bigger win chance?
Yes, with the same standard deviation. A higher standard deviation pulls the win chance back toward 50%.
Why enter both moneylines?
It lets the calculator remove the sportsbook's margin first, giving a fairer implied spread.
Start earning free reloads
Free to join. No deposit, no card. Cash out in LTC or USDT from $5.
Sign up freeSources
- Probability, Wikipedia (read 2026-10-05)
- Moneyline, Wikipedia (read 2026-10-05)
18+ only. ReloadRush is a free rewards site, not a casino: we do not offer gambling and do not sell coins or game credits. Not affiliated with any sweepstakes, social or online casino operator. Rules and state laws change, so check the operator's terms before you play.