A book's two prices add up to more than 100%. The overhang is the vig, and it comes out before anything is worth calling an edge. Paste the two sides and this gives you the fair number underneath them — the same engine the Oddcraft board grades on. No signup, nothing stored.
Both sides of the same market, in American odds.
| Side | Book | Book implies | True | Fair price |
|---|
The same side at every book you can reach. Best price wins; nothing else about the bet changes.
| Book | Price | Risk to win $100 | Wins $100 stake | Break-even |
|---|
A spread on a whole number can land exactly on it, and that push is neither a win nor a loss. Pricing it as impossible overstates your win probability and inflates every edge downstream. These rates are measured, not borrowed — and college is not the NFL.
| NFL spread | Push rate |
|---|---|
| 3 | 9.0% |
| 7 | 4.8% |
| 10 | 4.9% |
Closing-spread push estimates, calibrated separately from general scoring margins.
| NCAAF spread | Push rate |
|---|---|
| 1 | 5.5% |
| 2 | 2.1% |
| 3 | 6.9% |
| 4 | 2.0% |
| 6 | 1.4% |
| 7 | 8.2% |
| 10 | 7.5% |
| 14 | 3.3% |
Measured from CollegeFootballData: every FBS regular-season game 2021–2025 closing on a whole number, 2,699 games.
In college, 7 pushes more often than 3 — the reverse of the NFL. Talent gaps are wider and scores are higher, so the mass spreads out: only 19.2% of FBS games land on 3 or 7 against 24.3% in the NFL, and a third are decided by 21 or more. Using NFL rates on a college spread misprices it. Spreads outside these tables fall through to the plain de-vig rather than collect a guessed number.
They disagree about where the vig sits. Proportional shaves every side by the same ratio — simple, and what most free calculators do. Power solves for an exponent instead, which takes more from favorites and less from longshots. Shin treats the overround as the book protecting itself against informed money.
They agree exactly on a −110/−110 market; the gap opens as the price gets lopsided. Put −400 / +320 into the calculator above and switch between them: power puts the favorite at 78.65%, Shin at 78.10%. Just over half a point, and it runs the other way on the longshot. Every number on this page is one you can reproduce in it.