When paying attention to discourse in the betting community, you’ll often hear or see people discussing line moves. But, some moves are more impactful than others. Key numbers matter the most, and sports bettors should be aware of them and what they mean.
What are key numbers? Which markets do they influence? How should they affect the way you’re betting games?
We’ll go over the answers to these questions and more in this primer on key numbers in betting markets.
What Are Key Numbers?
Shifting prices in the markets – for example, a point spread between two teams moving from 3 to 3.5 – represent changes in implied probabilities. Knowledgeable bettors take them seriously.
All numbers have at least some impact. If a given game played out 1,000, 10,000 or 1,000,000 theoretical times, it would probably land on every reasonable number at some frequency.
But, it would land on some numbers more often than others. An easy way to see that is simply look at the margins of victory across some sample of NFL games. Teams win and lose by 3 and 7 more often than any other numbers.
That makes 3 and 7 key numbers. They frequently determine the winning and losing sides of bets.
For reference, check out this study. Even in 2015, the first year with the longer extra point, 3 and 7 decided more games than any other numbers – although 6 crept way up and wasn’t too far behind. Note that to a lesser extent, 4, 6 and 10 follow as the next most common margins. Fourteen as well, but since few spreads are near 14, it isn’t as actionable.
Together, these numbers accounted for more than 40% of decisive margins during the selected sample from this study.
Since we’ve been talking about NFL key numbers up to this point, it’s only natural to wonder if the concept extends to other sports. Do football, basketball and even hockey have key numbers?
Do key numbers exist in other sports?
Yes, they do, but the key numbers don’t possess near the impact they do in football and especially the NFL.
First, let’s get college football out of the way. While college football and the NFL are the same sport, they are different enough from a betting standpoint that you can’t simply port all your concepts from the NFL over and call it good.
Specifically in terms of key numbers, while the same numbers figure to have the biggest impact, the markets just contain more uncertainty in college compared to the NFL. Twenty-point margins happen every week on a regular basis – even in conference games. Therefore, key numbers don’t have quite the same value even if the idea holds some weight.
In the NBA, most of the teams wind up within 10 points of neutral on a per-100 possession basis. However, no particular numbers figure to have special significance. Note that volatility has only increased in recent years as the 3-point shot has become more prolific, leading to higher scoring and bigger swings. So, tread cautiously if you’re thinking of buying points.
With a few exceptions, baseball and hockey lines are generally plus or minus 1.5. However, totals do hold a few small biases. The most important thing to keep in mind is odd totals always end decisively. That is, the game can’t end tied and on a total like 5 or 7.
Because the most frequent winning margin is 1, you should expect close contests. And some permutations of even totals wind up tied (i.e., 4-4 lands exactly on 8) which means an under bet loses – and an over bet wins — whenever the decisive run or goal occurs in extra innings/overtime.
How do I approach key numbers when betting?
So, now that you know key numbers exist, what should you do about it?
Simply be vigilant and picky about the numbers into which you bet, assuming you wager in an attempt to profit. Have a number in mind, and if you can’t get that number, just pass and wait for a more profitable opportunity.
The most commonly applicable examples, again, come in the NFL. Well aware of the value of key numbers, sportsbooks often hang lines on either side of or right on them.
At the time of writing, 15 games have current markets for Week 1, the exception being Green Bay/New Orleans due to impact of Hurricane Ida. Of those 15 markets, 13 sit within a point of either 3 or 7. Narrowing further, 11 sit within half a point of these numbers.
If you like Dallas, you should likely bet them as soon as you can, unless you have some reason to believe the line will lengthen. That’s because, assuming equal likelihood of a move toward either team, a move toward Dallas hurts you more than a move toward Tampa helps. In other words, getting +7.5 versus +7 makes a large difference, where getting +8 instead of +7.5 doesn’t help all that much because games land on 8 infrequently.
If you like Tampa Bay, the opposite is true. Waiting to see if the number gets better won’t do you much harm.
Of course, if you do like the Bucs or a similar bet – on the wrong side of a key number – you should immediately line shop. Check the line at every sportsbook where you can place a bet and see if any have -7 instead of -7.5.
What role does the price play?
The vig, or the juice, on a spread bet can sometimes hint at which way a market is moving.
For example, imagine you think some runs are coming in a baseball game and you want to bet over the total. Maybe the over/under currently sits at 9.
Try to figure out which way the market seems to lean. Has the vig moved on one side? For example, say you saw under 9 at -110 early but it’s now -125. If the market continues to nudge that way, you might be able to wait and get over 8.5 instead of 9.
Say you’ve waited and line shopped but you can’t find the price you want. Should you “buy” half a point, paying extra to the sportsbook in exchange for a better line?
It depends how the book prices their lines, but they generally charge a premium to move on and off of key numbers. For example, it might cost you -135 to move off of 3, where it might cost you only -115 to move off of an innocuous number like 8.
You can find free-to-use half-point calculators online that tell you a fair price for buying half a point. Make sure you don’t overpay if you buy points.
How do key numbers relate to teasers?
Glad you asked. We have an entire page dedicated to teasers that you should check out right here.
The short version: when playing teasers in the NFL, make sure you buy key numbers. You want to target numbers where the teaser moves you through numbers that have the most value – +1.5 to +2.5 for underdogs and -7.5 to -8.5 for favorites, assuming standard 6-point teasers.
By the same token, if you’re playing “reverse teasers” or betting alternate lines, try to sell numbers you don’t expect to have a big impact.