This is a teaser calculator. You pick the number of teams, input each team’s spread and vig-free price, and the calculator outputs fair probabilities and American odds for teasers. It shows what those teasers “should” be priced.

It's different for each sport. For basketball spreads, each leg’s probability is anchored using the market spread and vig-free price. We infer the mean of the scoring-margin distribution and then shift the line by the teaser amount (making it more favorable for your side). The fair probability for the teaser is the product of the leg probabilities (assuming independence). Finally, that probability is converted back into American odds.

The calculator needs vig-free prices as inputs. If you use raw bookmaker lines (like -110/-110), the vig inflates both sides and would bias the result. Stripping out the vig ensures that the teased line pricing is anchored correctly to a fair probability.

Different sports have different scoring distributions. An NBA game has different scoring patterns and variance than an NFL game.

Totals influence variance (higher-scoring sports/events generally produce wider margins). More advanced calculators can adjust based on the game’s total, but this version keeps it simple.

They’re mathematically consistent with the assumptions of the model (For WBNA, Normal distribution, fixed standard deviation). That means they’re a strong approximation, but not perfect reality. Real-world pricing can differ. The calculator is best used as a reference point for whether an alternative line is priced fairly.