When you learn how to play Blackjack, one of the first things you should do is make sure the rules of basic strategy are hammered into your head.

You know, things like ‘Hit up to 17 when the dealer is showing a 7 or higher.’ Or ‘Stay at 12-16 when the dealer is showing bust.’ Or ‘Always split 8’s.’

Blackjack basic strategy is basic rules of thumb that ensure you have the best possible chance of winning.

### Key Numbers in Football Betting

There are similar rules when it comes to betting on football. One of the biggest rules is to know the key numbers in football.

A 2015 article by Sports Insights noted that 3 and 7 have overwhelmingly been the most common margins of victory in the NFL since 2003.

By knowing that more than 30% of NFL games are decided by either 3 points or 7 points, you realize that point spreads of 3 and 7 are the biggest key numbers in football betting.

*(Graph from SportsInsights.com)*

You’ll do everything possible to get your favourites at -3 instead of -3.5, and you’ll do your best to get +7.5 on your underdog instead of +7. You don’t worry as much about laying 5 points with the favourite instead of 4, and you might not take the underdog if you can only get +2.5 instead of +3.

It makes sense that 3 and 7 are the most key numbers in NFL betting because 3 is the value of a field goal and 7 is the value of a converted touchdown. The only other scoring in the NFL or NCAA football is on unconverted touchdowns (6 points), safeties (2 points) or two-point conversions instead of extra points.

How often do you see a game tied in the fourth quarter before a team drives for a winning field goal in the final minute? It explains why nearly 19% of NFL games are decided by 3 points. And while 7 may not quite be as key as it used to be because of the two-point conversion and because extra points are now the distance of 33-yard field goals, 11.5% of NFL games since 2003 have still been decided by a converted touchdown.

### CFL Football Is Different In Many Ways, Including Scoring

Canadian football is different from American football in many ways. The ball is bigger, the field is bigger, there are 3 downs instead of 4, several offensive players are allowed to be in motion before the snap, each team has an extra player on the field and the uprights are on the goal line, not at the back of the end zone.

**Another major way CFL football differs from NFL and NCAA football is the rouge (single point)**. In Canadian football, you can earn a point on a missed field goal that is not returned out of the end zone, or a punt that goes into the end zone and is not returned.

Since teams often score one or more rouges in a game, we wondered whether that would have an impact on the key numbers in CFL betting, compared to key numbers in American football. And here’s what we found.

### 3 Is Still Key In CFL, But Not Nearly As Much

From 2011-15, there were 404 games played in the CFL. This seemed like large enough of a sample size to make some conclusions.

The most common score differential in CFL games during that span was 3 points, similar to the NFL. That wasn’t any surprise. But what was interesting was the percentage.

Of those 404 games, 42 were decided by a field goal. That breaks down to 10.4 per cent – a notable amount, but nearly half the percentage of NFL games decided by 3 points (18.7%).

Another fascinating conclusion was that 7 points was not the second-most common score differential in CFL games during that time. It also wasn’t 6, or 10, or 4, or even 1 – all of which are fairly common margins of victory in the NFL.

It was 5!

Yep, approximately 6% of CFL games from 2011-15 (24 of 404) were decided by 5 points. Compare that to the NFL, where 5-point games were the 13th-most common differential – ranking behind 13 and 21, and barely ahead of 11.

The next most common margins of victory in CFL games were 1 (5.7% of the time) and 2 (5.5%), followed by 7 and 10 (tied at 5% each).

### Conclusions About Key Numbers In CFL Betting

We took away three conclusions after researching this piece about key numbers in CFL betting.

**1. Traditional Key Numbers Don’t Matter As Much**

Ordinarily, if you liked an underdog in football but could only get +2.5 instead of +3, or if you liked a favourite but could only get -3.5 instead of -3, you may end up passing on the game. In the CFL, 3-point games take place nearly half as often as they do in the NFL, so you can be more aggressive and take your chances on the +2.5-point dog or -3.5-point favourite. (We still suggest getting +3 if you can.)

**2. Traditional Dead Numbers Matter More**

Ordinarily, if you were getting a favourite at -5 or an underdog at +5, you probably wouldn’t look that hard to find -4.5 or +5.5. In the CFL, where 5 and other normally ‘dead numbers’ (like 2 and 12) come into play more often than in the NFL, you need to make sure you’re always getting the best possible point spread on your bets. Odds can vary by sportsbook, and those extra half-points can be the difference between a win and a push, or a push and a loss.

**3. Buying On And Off Key Numbers Doesn’t Make Sense**

It doesn’t appear to be worth buying points onto or off of 3 or 7 in the CFL. You could argue whether buying points is worth it in the NFL, but there isn’t much sense in paying 25 cents in juice (going from -110 odds to -135, for example) to move a point spread from +2.5 to +3 in the CFL, since you aren’t increasing your probability of winning by as much. You’re probably better off taking +2.5 at -110 instead of +3 at -135.