Key Numbers NFL: Why 3 and 7 Change Everything for Your Bets

You're breaking down a game. Your model (built on something like EPA) says the Chiefs should win by 4 points.

The spread is -3. Do you take the Chiefs?

Or the spread is -3.5. Still backing the same Chiefs?

The gap between -3 and -3.5 looks tiny — half a point. But in the NFL, that half-point can swing several percentage points in your probability of cashing a ticket.

Welcome to the world of Key Numbers — the magic digits of American football.

What Is a Key Number?

The Definition

A Key Number is a margin of victory that occurs more frequently than others in the NFL.

Because of the scoring system (touchdown = 6+1, field goal = 3), certain margins of victory show up far more often than the rest.

NFL Margins of Victory

Here is the distribution of margins of victory across 20+ NFL seasons:

Margin	Frequency	Cumulative
3	~15%	15%
7	~9%	24%
6	~5%	29%
10	~5%	34%
4	~4.5%	38.5%
14	~4%	42.5%
1	~4%	46.5%
17	~3.5%	50%

Games land on a 3-point margin roughly 15% of the time.

That is massive. About one in every six or seven games.

Why 3 and 7 Dominate

The NFL scoring system explains everything:

Score	Points
Field Goal	3
Touchdown + PAT	7
Touchdown + 2PT	8
Safety	2

The most common scoring combinations:

3  = 1 FG difference
7  = 1 TD difference
6  = 1 TD (missed PAT) difference
10 = 1 TD + 1 FG difference
14 = 2 TD difference
17 = 2 TD + 1 FG difference

The Main Key Numbers

Tier 1: The Untouchables

Key Number	Frequency	Importance
3	~15%	Critical
7	~9%	Very High

These two numbers alone account for nearly 25% of all margins of victory.

Tier 2: Important

Key Number	Frequency	Importance
10	~5%	Important
6	~5%	Important
14	~4%	Moderate

Tier 3: Secondary

Key Number	Frequency	Importance
4	~4.5%	Secondary
17	~3.5%	Secondary
13	~3%	Secondary
1	~4%	Secondary

Visual Hierarchy

Key Number Importance:

3  ████████████████████████████████ (15%)
7  ████████████████████ (9%)
10 ██████████ (5%)
6  ██████████ (5%)
14 ████████ (4%)
4  █████████ (4.5%)
1  ████████ (4%)

The Impact on Spreads

The -3 Scenario

The most common spread in the NFL is -3 (or +3).

Spread	What happens if the favorite wins by exactly 3
-3	Push (bet refunded)
-3.5	Bet lost
-2.5	Bet won

The gap between -2.5 and -3.5 is ENORMOUS in the NFL.

Quantifying the Difference

Assume you are betting on the favorite:

Spread	Estimated Win % (if "true" line = -3)
-2.5	~52% (you win if margin >= 3)
-3	~47% (push at 3, win if > 3)
-3.5	~44% (you lose if margin = 3)

Moving from -3 to -3.5 costs you roughly 3% in win rate.

Over 100 bets, that is 3 fewer wins — a huge difference long-term and critical for your bankroll management.

The -7 Scenario

Same logic applies to 7:

Spread	What happens if the favorite wins by exactly 7
-7	Push
-7.5	Bet lost
-6.5	Bet won

The impact is smaller than for 3 (9% vs 15% frequency), but still significant.

The "Hook" and Its Value

What Is the Hook?

The hook is the half-point added to a spread: -3.5 instead of -3, +6.5 instead of +7.

Term	Meaning
-3	Exactly three points
-3.5	Three and a half (with the hook)
+7	Exactly seven points
+6.5	Six and a half (hook on the other side)

The Value of the Hook on Key Numbers

The hook does not carry the same weight everywhere:

Spread	Hook Value
-3 to -3.5	Very High (~3% win rate)
-7 to -7.5	High (~2% win rate)
-10 to -10.5	Moderate (~1% win rate)
-5 to -5.5	Low (~0.5% win rate)
-8 to -8.5	Low (~0.5% win rate)

How Much Should You Pay for the Hook?

Sportsbooks sometimes let you buy points. Here is what they are worth:

Hook	Value in Juice
-3 to -2.5	Worth ~15-20 cents of juice
-3.5 to -3	Worth ~10-15 cents of juice
-7 to -6.5	Worth ~10-12 cents of juice
-7.5 to -7	Worth ~8-10 cents of juice
-4.5 to -4	Worth ~3-5 cents of juice

Example: - Spread: -3.5 at -110 - Buying the hook to -3 for -120 = often worth it - Buying the hook from -5.5 to -5 = rarely worth it

Key Number Strategies

Strategy #1: Take the +3 Over the -3

If you are on the fence about a game with a spread of 3:

Underdog +3 > Favorite -3 (at equal odds)

Why? The push at 3 protects you from both sides.
But with +3, you also win if the underdog wins outright.

Outcome	Favorite -3	Underdog +3
Favorite wins by 7	Win	Loss
Favorite wins by 3	Push	Push
Favorite wins by 1	Loss	Win
Underdog wins	Loss	Win

The underdog +3 covers more winning scenarios (including every outright win).

Strategy #2: Avoid -3.5 on the Favorite

If your analysis says the favorite should win by 3-4 points:

Spread -3: Bet it
Spread -3.5: Pass or shop for a better number

The 0.5-point difference = ~3% in win rate.
That is massive.

Strategy #3: Line Shop Around Key Numbers

Hunt for the best lines whenever a Key Number is in play:

Book A	Book B	Book C	Action
-3 (-110)	-3.5 (-110)	-3 (-105)	Bet at C
+2.5 (-110)	+3 (-110)	+3 (-115)	Bet at B (free hook)

Line shopping is CRUCIAL around Key Numbers.

Strategy #4: Buy the Hook Wisely

Situation	Buy the Hook?
-3.5 to -3	Yes, often (if < 15 cents)
-7.5 to -7	Yes, often (if < 12 cents)
-10.5 to -10	Maybe (if < 8 cents)
-6.5 to -6	Rarely (6 is less common)
-4.5 to -4	No (4 is not a strong key number)

Strategy #5: Teasers and Key Numbers

Teasers (buying 6-7 points across multiple legs) are optimized around Key Numbers:

Optimal teaser:
- Favorite at -7.5 to -8.5 -> teased to -1.5 to -2.5 (crosses both 3 AND 7)
- Underdog at +1 to +2.5 -> teased to +7 to +8.5 (crosses both 3 AND 7)

A strong teaser crosses multiple Key Numbers.

How Key Numbers Have Evolved

The PAT Rule Change (2015)

In 2015, the NFL moved the PAT (Point After Touchdown) from the 2-yard line to the 15-yard line. Impact:

Before 2015	After 2015
PAT success rate: 99.5%	PAT success rate: ~94%
Score of 7 very common	Score of 6 more frequent

Result: The number 6 became slightly more important as a Key Number.

The Rise of 2-Point Conversions

Teams are attempting more 2-point conversions than ever:

Period	2PT Attempts/Season
2010-2014	~80
2015-2019	~100
2020-2024	~130

Impact: Margins of 8 (TD + 2PT) are becoming slightly more frequent.

Key Numbers Remain Stable

Despite these shifts, 3 and 7 continue to dominate:

3 still accounts for ~14-16% of margins
7 still accounts for ~8-10% of margins

These numbers have been remarkably stable for 30 years.

Applying Key Numbers to Totals (Over/Under)

Do Key Numbers Matter for Totals?

Less directly, but certain final totals are more common:

Final Total	Frequency
41-47	More common
37-40	Common
48-54	Common
< 30	Rare
> 60	Rare

The Case of 41, 44, 47

Totals that are multiples of 3 or 7 are slightly more frequent:

37 = (TD+TD+TD+FG+FG+FG) + (TD+TD)
44 = (TD+TD+TD+FG) + (TD+TD+FG)
51 = (TD+TD+TD+TD+TD) + (TD+TD+FG)

Strategy for Totals

Total	Tip
43.5 vs 44	The half-point matters less than on spreads
47.5 vs 48	Slight importance
41	A total that hits often

In general, Key Numbers are LESS important for totals than for spreads.

Practical Examples

Example #1: Choosing Between -3 and -3.5

Game: Chiefs @ Raiders

Your analysis: Chiefs should win by 4-5 points.

Option	Spread	Odds	Recommendation
A	Chiefs -3	-115	Take it
B	Chiefs -3.5	-110	Proceed with caution
C	Chiefs -3	-105	Excellent value

Reasoning: - Your projection (4-5 pts) is close to 3 - A push at 3 is likely (~15% of games) - Paying 5 cents for the hook (-115 vs -110) = worth it

Example #2: The Optimal Teaser

Two games: - Bills -8 vs Jets - Packers -7.5 vs Bears

6-point teaser: - Bills -8 becomes -2 (crosses both 7 AND 3) - Packers -7.5 becomes -1.5 (crosses both 7 AND 3)

Analysis: - Bills at -2: Win if they take it by 3+ (instead of 8+) - Packers at -1.5: Win if they take it by 2+ (instead of 8+) - Both legs cross the Key Numbers — optimal teaser

Example #3: Critical Line Shopping

Game: Cowboys vs Giants

Book	Spread	Odds
DraftKings	Cowboys -3.5	-110
FanDuel	Cowboys -3	-110
BetMGM	Cowboys -3	-105

Action: Bet at BetMGM - You get -3 (hook in your favor) - PLUS better odds (-105 vs -110) - Total edge: ~3-4% win rate + 5 cents of juice saved

Example #4: When -7 Matters

Game: Ravens @ Bengals

Line: Ravens -6.5

Your analysis: Ravens win by 7-8 points.

Decision	Reasoning
Take -6.5	You win if Ravens win by 7+
DO NOT buy to -7	A push at 7 is less frequent than a push at 3

Here, keeping -6.5 is the right call because you want to capture wins by exactly 7.

Common Mistakes

Mistake #1: Ignoring Key Numbers

Wrong: "The spread is -3.5, close enough to -3"
Right: "-3.5 costs me ~3% in win rate vs -3 — that is significant"

Mistake #2: Buying Points on Non-Key Numbers

Wrong: "I will buy -5.5 down to -5 for safety"
Right: "5 is not a Key Number — the juice is not worth it"

Mistake #3: Skipping Line Shopping

Wrong: "I always bet at the same book"
Right: "I compare 3-4 books, especially around Key Numbers"

Mistake #4: Overvaluing Key Numbers on Totals

Wrong: "The total is 44, that is a Key Number — I need to buy points"
Right: "Key Numbers matter much less on totals than on spreads"

Mistake #5: Betting -3 When Your Projection Is Far Off

Wrong: "I am taking -3 because it is a Key Number"
Right: "My projection is -7 — the -3 line is irrelevant here"

How ProbWin Uses Key Numbers

Our NFL model integrates Key Numbers into the analysis:

1. Estimate the "true" spread (our projection)
2. Compare it to the market line
3. If close to a Key Number -> adjust the value assessment
4. Evaluate the hook (half-point)
5. Factor Key Numbers into the recommendation
6. Suggest line shopping opportunities when applicable

Key Numbers shift our betting threshold: - Projected spread 3.5, line -3 -> slight value - Projected spread 3.5, line -3.5 -> reduced value

Check out our NFL picks to see this analysis in action.

Summary: Key Numbers in 7 Points

#	Takeaway
1	3 (~15%) and 7 (~9%) are the major Key Numbers
2	Going from -3 to -3.5 costs ~3% in win rate
3	The hook (half-point) is most valuable on Key Numbers
4	Line shopping is CRUCIAL around 3 and 7
5	Underdog +3 > Favorite -3 at equal odds
6	Optimal teasers cross multiple Key Numbers
7	Key Numbers matter less for totals

What's Next

You now have a solid grasp of Key Numbers. But in the NFL, some games carry a special emotional charge: revenge games and divisional matchups.

Find out whether these narrative factors actually move the needle — or if it is all just storytelling.