Half Point Calculator

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The majority of online sportsbooks offer the ability to purchase half points off point spreads and totals. This is generally at 10 cents each. If a point spread is 5.5 you can bet the favorite -5.5 -110, -5 -120, or -4.5 -130 or the underdog +5.5 -110, +6 -120, +6.5 -130. The same can be done for over/under betting (NFL based). In this article I explain when it is and isn’t mathematically correct to purchase half points.

Half-Point Betting Math

The math to evaluate value a half point purchase is simple. For starters use an odds converter. On that page you can enter -110 and see under implied probability it shows 52.38%. This is how often a bet at -110 needs to win to average break even. If you now enter -120 you’ll see the required win percentage to break even becomes 54.55%. That’s a difference of 2.17%.

To put this into perspective let’s say we’re looking at an NBA point spread +6.5 -110. Based on the math above we would only instead bet +7 -120 if having +7 instead of +6.5 increases our expected win rate by the required 2.17%. Well, I happen to have a push chart that shows NBA teams that are favored by about 6.5 points win by exactly 7 about 4.1% of the time. In this case we are going to pass on buying the half point because we are only increasing our cover rate by 2.05% (half of the 4.1% probability of the favorite winning by exactly 7) and needed 2.17%+.

Are you confused about why we only took half the 4.1%? To explain: When we had +6.5 if the game ended with the favorite winning 7 we lost and the bookie who had -6.5 won. Moving to 7 both of us push. Therefore that extra 4.1% of value for teams winning by exactly 7, half is on our line of +7 and half is in the bookies line of -7. We gained his share of the 7 on that move. When going from a push to a win the same is true. For example: when going -7 to -6.5 or going +6.5 to +7 our push probability increases by half the probability of that game ending with the favorite winning by 7 points.

Creating Push Charts

The half-point calculator to the left calculates the fair price for half-point buys in NFL football betting. This tool is helpful for both line shopping and purchasing half points with bookmakers. Regarding line shopping say BetOnline is offering Patriots -4 -110 and Bovada is offering Patriots -3 -140. Make grading easy by generating grades based on the number of possible questions. If a different grading scale is needed, then adjust the grade scale to reflect different levels. GradeCalculate's Easy Grader is built for teachers by teachers.

It is important to understand each half-point has unique value. In NFL football nearly 16% of all games are decided by EXACTLY 3 points and nearly 10% by EXACTLY 7 points. Those are the two most common margins of victory. In basketball end game strategy with intentional fouls, killing clock, playing for final shots, etc. leads to certain numbers being more likely to occur than others. In low scoring sports like hockey and soccer the chances a total will be an odd (instead of even) number is significant. So the calculations will need to be ran separately for each half point.

It is a good idea to do these well in advanced. How to go about it for most sports would be using point spreads of +/- 1.5. What this means is to calculate the push rate on favorite by 6, look for all similar games where the point spread was between 4.5 and 7.5 and see how often those games finished with the favorite winning by EXACTLY 6. If you calculate this in advanced and list it in a spreadsheet or even just draw some sort of table or list it in a note pad you’ll have it handy anytime it is needed.

Half point calculator

As far as getting the data two of my recommended books about sports betting contain value for this. Sharp Sports Betting by Stanford Wong, while outdated, has push charts inside it. These can be used as a rough guide. Or you can use SBR’s half point calculator to capture their push rates on sides and totals for NBA, College Hoops, NFL, College Football, MLB and NHL. Their data is also outdated. It is the other book Conquering Risk that has more value to serious punter. This covers how to scrape content from the web.

If you decide to scrape data there are many potential sources. One is Covers.com which has historical spreads and results going back many years. A better source for recent years is SBROdds.com. Here the calendar at the top (to the right of where it says today / yesterday) can be used to navigate through historical odds and results at multiple sportsbooks. The best one to scrape and use is Pinnacle Sports. Once you have the database – you can create your push chart.

Finding Value Buying Half Points

The key to finding value in purchasing half points is to understand the more half-points you purchase the more each is worth in value. Let me show you why. Let’s say a bookie offers up to 8 half points at 10 cents each. So this is -110 (52.38% implied probability) vs. +8 -190 (65.52% implied probability).The difference is 13.14% or in other words 1.64% per half point. That’s much better than the 2.17% paid when going from -110 to -120. How is this the case?

Nfl half point calculator

The reason is because moneylines are based on percentages. 10 cents means nothing in and of itself. To show this further again -110 to -120 increases the required win rate to break even by 2.17%. Again, using our odds converter I can see -120 has an implied probability of 54.55% and -130 of 56.52%. Here the move is again 10 cents but the difference is 2.03% not 2.17%. In that NBA example earlier, the 7 was worth 2.05%. Had the question been +6.5 -120 or +7 -130 we would take +7 -130 because the push on 7 increases our win rate by more than the 2.03% difference in implied probability.

To give an extreme example, going from -180 (64.28%) to -190 (65.52%) has a difference of just 1.24%!. The bigger the moneyline odds the more likely it is that purchasing a half point at 10 cents is a good deal! So how can we can we make money from this?

As a general rule of thumb in basketball it takes 6 half points at 10 cents each to have a tiny edge over the bookmaker. If you can do more than that, with good bankroll management, you practically have a money printing machine. For example 4 points for -190 instead of -110 gives an expected ROI of about 3.6%. While sites like BetUs.com (not very reputable) used to offer 8 points for 80 cents, today most bookies are wise and such deals are uncommon. The smartest bookies limit the number of half points that can be purchased to 2 or 3 before they start to charge a premium.

The most logical place to find value should be in NFL point spreads on the most common margins of victory 3 and 7. Unfortunately, here once again the bookies charge a premium. Going from +2.5 to +3, +3 to +3.5, -3.5 to -3, and -3 to -2.5 costs 25 or 30 cents at most bookies. Going from +6.5 to +7, +7 to +7.5, -7.5 to -7, and -7 to -6.5 costs 15 or 20 cents. This can still sometimes be worth it when the ML is large. What is however more common is to find value on the half points they don’t charge a premium for. Worth noting is that the third most common margin of victory in NFL football is 10. Should I continue?

Let me just tell you buying half points is one of the many ways I personally make money betting sports. If I however told you which sites allow 4 half points at 10 cents each (yes these exist) or what the most common margins of victory are for every league, this article will become outdated quickly. Why? Because everyone will be beating the sportsbook that offers +EV point buy opportunities. That book will eventually notice and adjust their odds. This has happened many times in the past. Years ago basic strategy NFL teasers were profitable at most sites, today they are not. Years ago there was much more value in buying half points, but today bookies grown wiser.

If you do the work to make push charts, find the most common margins of victory, and learn which bookies offers what, you will soon be able to create a system. Every time a specific point spread pops up you know “at book XYZ I need to do X”. If you have that system you are making money. At that point you will be glad I concluded this article the way I did. It is important only a limited number of people take advantage of the +EV angles, because eventually they dry up.

Author: Jim Griffin

Note: the article and tool below is for experienced bettors. If you’re new to sports betting and have never placed a bet, visit our page on NFL bet types.


Advanced Look at NFL Point Spreads

The half-point calculator to the left calculates the fair price for half-point buys in NFL football betting. This tool is helpful for both line shopping and purchasing half points with bookmakers. Regarding line shopping say BetOnline is offering Patriots -4 -110 and Bovada is offering Patriots -3 -140. To determine which is the better bet enter -4 and -110 into the calculator and you’ll see the -3 equivalent of -4 -110 is -3 -142.6. In this example -3 -140 at Bovada is a better bet than -4 -110 at BetOnline.

Understand our calculator uses NFL averages. In cases of games where the over/under betting line is high (say 45.5+) each half point will be worth a little less. So if our calculator tells you -4.5 -105 is the same as -4 -111.5 it might actually only be worth -111. In cases where the total is low (say 40.5 or less) each half point is worth more. In the same example -4.5 -105 might be worth -4 -112 instead of the -111.5 our calculator displays. The point is you’ll need to make small adjustments for games with a lower or higher than average over/under betting total.

Fair Odds (No-Vig): Also understand our calculator deals with fair odds. We do not attempt to determine how much vig was in the moneyline odds entered and propriate an equivalent the same way our no-vig calculator does. In short if the fair odds were -10 -110, we’ll show you the equivelent fair odds for -9.5, -9.0 and -8.5. Creating advanced NFL push charts and doing out the math can lead to much more precise results; however our calculator works extremely well on average and can be a great time saver.

Understanding Buy Point Strategy

Our NFL Half Point Calculator is a great time saver. However, when dealing with point spreads that have juice, or when you desire to be more precise, understanding the math behind half points is helpful. In this article I’ll cover this topic in some depth.

Half way driving point

Calculating Half Point Equivalents

The first thing to understand is that all prices have an implied probability equivalent. For -3 -111 the -3 is the point spread and the -111 is the price. To calculate the implied probability we need to use the formula risk/return=implied probability. To be clear return includes both stake plus win, so for example at -111 a bet of $111 to win $100 has a return of $211 (stake+win). In this example 111/211= 0.5261 which changed to a percentage is 52.61%. This means when betting at -111 you’ll need to win 52.61% of the time to break even and this 52.61% is referred to as the implied probability.

Let’s examine -3 -111 moved to -2.5. All that’s change here is we win instead of push when the favorite wins by exactly three. To calculate the -2.5 equivalent we need to determine exactly how often teams favored by -3 win by exactly 3 points. Using a combination of historical results data and no-vig lines at sharp betting sites I determined this happens about 9.80% of the time. I just calculated one paragraph up that -111 has a 52.61% equivalent. If I add half 9.8% I get an implied probability of 57.51%. I can now go to our odds converter, plug in 57.51% in the implied probability field and see in American odds format this is -135. Therefore -3 -111 and -2.5 -135 have the same expected win/loss.

Why did I use only half of 9.8%? If we were moving from -3.5 to -2.5 I could have used the full 9.8% probability of 3 as we’d of picked up all of that probability. The reason I couldn’t do this is because we were moving from a push to a win (I also would use half when moving from a loss to a push). You see that 9.8% is built half into our line of -3 and half in the opposite team’s line of +3 and for this reason we can only take half the probability.

When should I Purchase Half Points?

The first thing to understand is not all half points are created equal. For example the push probability of 3 is about 9.8% and the push probability of 7 is about 5.72%. These are the two most common margins of victory. Meanwhile -9 only pushes 0.9% of the time, and -12 about 0.44% of the time. Many online sportsbooks sell half points involving the 7 for 15 cents, half point involving the 3 for 25 cents and all other half points at 10 cents each. Under this cost per half point pricing there are only sixteen scenarios where purchasing half points is a better bet than passing on the option to do so.

When to Purchase Two Half Points

  • -3.5 purchase to -2.5 by purchasing two half points for 50 cents
  • +2.5 purchase to +3.5 by purchasing two half points 50 cents
  • -10.5 purchase to -9.5 by purchasing two half points 20 cents
  • +9.5 purchase to +10.5 by purchasing two half points 20 cents
  • -14.5 purchase to -13.5 by purchasing two half points 20 cents
  • +13.5 purchase to +14.5 by purchasing two half points 20 cents
  • -17.5 purchase to -16.5 by purchasing two half points 20 cents
  • +16.5 purchase to +17.5 by purchasing two half points 20 cents

When to purchase One Half Point

  • -3 to -2.5 by purchasing one half points for 25 cents
  • +3 to +3.5 by purchasing one half points 25 cents
  • -10 purchase to -9.5 by purchasing one half points 10 cents
  • +10 purchase to +10.5 by purchasing one half points 10 cents
  • -14 purchase to -13.5 by purchasing one half points 10 cents
  • +14 purchase to +14.5 by purchasing one half points 10 cents
  • -17 purchase to -16.5 by purchasing one half points 10 cents
  • +17 purchase to +17.5 by purchasing one half points 10 cents

Outside of these scenarios when half points cost 25 cents involving point spreads of 3, 15 cents involving point spreads of 7 and 10 cents for all other half points, there are few other circumstances when buying half points makes sense. The one known exception is in cases of -7.5 -115 or +6.5 -115, here purchasing two half points for 15 cents each is slightly better than passing on the option. Just make sure via line shopping you can’t beat the -115 because if you can beat it betting straight would be the better play.

Half Point FAQ

Q. How do I develop a push chart?
A. Historical data weighed 25% and removing vig from Pinnacle Sports lines weighed 75% is a decent rough way to go about it. To get really advanced you’d need to simulate the actual game.

Q. What Push Probabilities Does the Half-Point Calculator Use?
A. Our tool uses the following push probabilities: -1 (2.50%),-2 (1.98%), -3 (9.80%), -4 (3.00%), -5 (1.68%), -6 (3.40%), -7 (5.72%) -8 (2.14%), -9 (0.90%), -10 (4.92%), -11 (2.22%), -12 (0.44%), -13 (1.33%), -14 (4.9%), -15 (1.46%), -16 (3.48%), -17 (4.55%), -18 (2.33%).

Q. Which Sportsbooks offer half point buys?
A. The majority of online sportsbooks offer this, the only one I’m aware that doesn’t is bovada.lv. Bookmaker.eu, BetOnline, Legends, 5Dimes etc. all offer this feature.

Editor’s note: If you enjoyed this article and are looking to learn more about football betting I suggest visiting our hub on football betting strategy.

Half Point Calculator

Author & Professional: Jim Griffin