Rex says
The fast lane for the math you almost remember from school. Type the numbers, get the answer, move on with your day.
Try a scenario
Click to load — tweak from there.Inputs
Result
Extra win-rate needed to justify buying
4.14%
Break-even at original line
52.38%
Break-even at bought line
56.52%
Profit given up per win by buying
$13.99
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How to use this
- 1Enter original odds (american).
- 2Enter odds after buying points.
- 3Enter stake ($).
- 4Read your extra win-rate needed to justify buying on the right — it updates as you type.
- 5Hit Share to keep the scenario or send it to someone.
About this calculator
Sportsbooks let you 'buy' points off a spread — moving a -7 favorite to -6.5, for example — in exchange for worse odds, typically an extra 10-25 cents of vig per half-point depending on which key number you're crossing. Buying off a key number like 3 or 7 in the NFL is usually considered worthwhile because those margins occur unusually often as final scores; buying a non-key number, like moving -9.5 to -9, usually is not, because the incremental win-probability gain is small relative to the extra cost. This calculator takes your original and bought-up odds along with your stake, then shows the break-even win-rate difference required to justify the extra cost, so you can compare it against how often that specific point actually shows up as the final margin in historical data (a number this tool doesn't have — you'll need to bring that from a key-number chart or your own research).
Worked example
Using the values the calculator loads with:
Inputs
- Original odds (American): -110
- Odds after buying points: -130
- Stake: 100 $
Results
- Extra win-rate needed to justify buying: 4.14%
- Break-even at original line: 52.38%
- Break-even at bought line: 56.52%
- Profit given up per win by buying: $13.99
What each field means
Inputs
- Original odds (American)
- The original odds (american) used in the calculation. Starts at -110 so you have a working example on load.
- Odds after buying points
- The odds after buying points used in the calculation. Starts at -130 so you have a working example on load.
- Stake ($)
- The stake used in the calculation, measured in $. Starts at 100 $ so you have a working example on load.
Results
- Extra win-rate needed to justify buying
- Returned as a percentage and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Break-even at original line
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Break-even at bought line
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Profit given up per win by buying
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
What are the NFL's key numbers and why do they matter here?
3 and 7 are by far the most common final-score margins in the NFL because of how touchdowns, extra points, and field goals combine, followed by smaller bumps at 4, 6, 10, and 14. Buying a spread across 3 or 7 (say -7.5 to -6.5) captures disproportionately more win probability than buying an equivalent half point elsewhere, like -9.5 to -8.5, which crosses no key number.
How do I know if the extra win-rate requirement is worth paying?
Compare the extra win-rate this calculator shows you need against a key-number margin distribution chart (widely available from betting research sites), which tells you the actual historical frequency of that specific final margin. If crossing the number historically adds more win probability than the extra cost requires, buying is a good value; if it adds less, you're paying for protection you don't need.
Does buying points ever make sense outside the NFL?
It applies to any point-spread sport, but key-number effects are much weaker in sports with more continuous scoring distributions, like basketball, where win margins are more spread out and no single number dominates final margins the way 3 and 7 do in football. Buying points in the NBA is generally a worse value than doing so around NFL key numbers.
Accuracy and limitations
- Results are rounded for display; the underlying calculation keeps full precision.
- Very large or very small inputs may hit floating-point limits in the browser.
- Inputs outside the accepted range are clamped rather than rejected.
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Teaser & Pleaser Math Calculator
See adjusted payouts and break-even rates for NFL teasers and pleasers.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Buy Points Cost Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/buy-points-cost-calculator
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/buy-points-cost-calculator" target="_blank" rel="noopener">Buy Points Cost Calculator — RevenueLab</a> (2026).</p>
Source: [Buy Points Cost Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/buy-points-cost-calculator) (2026).