In NFL line betting the bookmaker adds a points start to the underdog's final score, or takes it off the favourite's, and you bet on who is ahead after that. At -3.5 the favourite must win by at least 4, while +3.5 on the underdog pays if it loses by 3 or less, ties or wins, which matters because 3 is the most common margin in the NFL.
US coverage calls the same bet the point spread. Both sides are normally priced close to even money, so in the NFL the exact number on the line deserves as much attention as the price. The US sports betting guide covers the other markets and leagues.
How a -3.5 line settles on a 3-point and a 4-point win
Settle it by adjusting the score: knock 3.5 points off the favourite's total, or add 3.5 to the underdog's, and whichever side leads after that wins. With illustrative prices of $1.95 on the favourite at -3.5 and $1.87 on the underdog at +3.5, here is $60 on each side across five final scores:
| Final score, favourite first | Margin | Favourite -3.5 at $1.95 | Underdog +3.5 at $1.87 |
|---|---|---|---|
| 24-20 | Favourite by 4 | Wins, returns $117.00 | Loses $60 |
| 27-24 | Favourite by 3 | Loses $60 | Wins, returns $112.20 |
| 34-17 | Favourite by 17 | Wins, returns $117.00 | Loses $60 |
| 17-17 after overtime | Tie | Loses $60 | Wins, returns $112.20 |
| 20-23 | Underdog by 3 | Loses $60 | Wins, returns $112.20 |
The 4-point win clears 3.5 by half a point and the 3-point win falls half a point short. At -3 the 27-24 result would be a push, which commonly returns the stake, and at -2.5 it would win.
Example: Illustrative prices only. A winning favourite bet pays 60 x 1.95 = $117.00 back, $57.00 of it profit, and a winning underdog bet pays 60 x 1.87 = $112.20, a $52.20 profit.
Together the two prices make a book of 1 / 1.95 + 1 / 1.87 = 0.5128 + 0.5348 = 104.8%, the 4.8% above 100% being the bookmaker's margin. US coverage would quote them as -105 and -115: 100 / 105 + 1 = $1.95 and 100 / 115 + 1 = $1.87. The odds converter turns any other US price into decimal.
Point spread, handicap and points start
In Australia the NFL point spread, or the spread, is sold as the line in decimal odds. Handicap and points start are other names for it, and covering the spread means winning a line bet. A pick'em, written PK, is a game with no line, and an against the spread record counts a team's results against the line instead of its wins and losses. The US betting terms guide maps the rest of the slang.
For bookmakers authorised in NSW, the Bookmaker Declared Betting Events Betting Rules set a points start to half a point unless the bookmaker and customer agree otherwise (clause 5.1.3). A whole-number line such as -3 is an agreed exception there, and other bookmakers set their own terms.
Why NFL lines cluster around 3 and 7
NFL scoring comes in lumps: 3 for a field goal and 7 for a touchdown with its kicked try (Rule 11). Games therefore finish 3 or 7 points apart more often than any other margin, 14.6% and 7.7% of the 1,359 regular-season games from 2021 to 2025.
A line is set near the margin the market expects. When that is close to a field goal, the choice between -2.5, -3 and -3.5 decides whether the single most common result wins, pushes or loses. A step from -3 to -3.5 therefore changes a bet's chance far more than a step from -5 to -5.5.
That is why a bookmaker can hold a line on 3 and move the price instead, offering -3 at $1.80 rather than -3.5 at $1.95 (illustrative). NFL key numbers has the full margin table behind this.
Buying a half point and what it costs
Buying points is the US name for taking a line nearer your side at a lower price, which Australian bookmakers sell as alternate lines or pick your own line. A half point changes how one exact margin settles, so its whole value is the chance of that margin.
With illustrative prices, say you rate the favourite a 50% chance to win by 4 or more and a 7.5% chance to win by exactly 3. Expected value per $1 = win chance x price + push chance - 1:
| Line | Price | Wins on | Pushes on | Expected value per $1 |
|---|---|---|---|---|
| -3.5 | $1.95 | 4 or more (50%) | Nothing | 0.50 x 1.95 - 1 = -2.5c |
| -3 | $1.80 | 4 or more (50%) | Exactly 3 (7.5%) | 0.50 x 1.80 + 0.075 - 1 = -2.5c |
| -2.5 | $1.70 | 3 or more (57.5%) | Nothing | 0.575 x 1.70 - 1 = -2.25c |
At these prices the half point onto 3 costs exactly what it adds. The rule behind that: moving from -3.5 to -3 pays only if the chance of an exact 3-point win is at least the win chance times the price you give up, here 0.50 x (1.95 - 1.80) = 7.5%.
As a rough benchmark, 199 of the 1,359 games from 2021 to 2025 ended exactly 3 apart, about 7.3% for one side once halved. That average includes mismatches, and a game priced around a field goal should land on 3 more often, so treat 7.3% as a starting point rather than this game's chance.
The same 15-cent cut is poor value away from 3 and 7. With a 50% chance of a win by 5 or more, moving from -4.5 at $1.95 to -4 at $1.80 needs a 7.5% chance of an exact 4-point win. Only 69 of the 1,359 games (5.1%) ended 4 apart, about 2.5% for one side.
At 2.5% the buy turns -2.5c into 0.50 x 1.80 + 0.025 - 1 = -7.5c per $1, so the half point costs an extra $5 on every $100 staked. The half point line entry covers the .5 in every sport.
Risk: Betting involves risk. The 50% and 7.5% are illustrative judgements, not known chances, and a half point bought at a fair price still loses whenever the margin misses it. See responsible gambling for limits and support.
Ties, overtime and the line
In the regular season, a game level after four quarters gets one 10-minute overtime period. Each team must get a chance to have the ball, unless the side kicking off scores a safety on the first possession or the 10 minutes run out first. A score still level at the end stands as a tie, while playoff games play on until there is a winner (Rule 16). For a line bet, three things follow.
Overtime counts. The NSW rule book settles a points start including any extra time unless agreed otherwise (clause 5.1.3), and full-game lines commonly do the same at other bookmakers. A first-half or first-quarter line is decided before overtime begins.
A tie is a margin of 0, so every minus line loses and every plus line wins: a 17-17 finish beats +0.5 and +3.5 alike. Only a pick'em line of 0 pushes on a tie.
Overtime has its own margins. A touchdown that ends it carries no try, so 3 and 6 dominated overtime results until the NFL's 2025 rule change, approved on 1 April 2025, gave both teams a chance at the ball.
Example: Illustrative price. You have $40 on Team A -1.5 at $1.85, and the game is 20-20 after four quarters. Team A kicks a field goal in overtime and Team B's possession ends without a score, so Team A wins 23-20, and 23 - 1.5 = 21.5 beats 20 for a return of 40 x 1.85 = $74.00. Had overtime ended 20-20, the same bet would have lost.
How quarterback news moves an NFL line
The NFL's official injury report lists each player's practice participation through the week and a game status of out, doubtful or questionable. The last word comes on game day, when each club hands its list of inactive players to the referee 90 minutes before kick-off. For a Thursday night game at 8:15 pm US Eastern time, from November that is 10:45 am Friday in Sydney, 9:45 am in Brisbane and 7:45 am in Perth.
The quarterback takes the snap on nearly every offensive play, so a starter ruled out is the team news most likely to move a line a long way. There is no fixed value: the market moves the line by however many points it rates the gap to the backup, and where the move lands matters as much as its size.
Say the line is -6.5 midweek, the favourite's starting quarterback is ruled out and the line re-opens at -2.5 (illustrative). That move crosses the margins 6, 5, 4 and 3, which together decided 420 of the 1,359 games from 2021 to 2025 (30.9%). A 4-point move from -11.5 to -7.5 would cross 11, 10, 9 and 8, which decided 170 games (12.5%). The two moves are the same size, but the first changes the result of well over twice as many games.
A bet placed before the news keeps its line: the underdog at +6.5 still covers a 6-point loss that the new +2.5 does not, while the favourite at -6.5 is now 4 points harder than the market's view. Closing line value explains why beating the final line, bet after bet, is the usual test of whether your prices are good.
Team news for the early Sunday games can arrive while you sleep. A bet that depends on it is one to skip unless you have seen the news before you go to bed and the line still suits your view.
Risk: Betting involves risk. Beating the closing line is a sign of a good price, not a winning bet, and a line taken early can move against you just as easily. See responsible gambling for limits and support.
NFL line betting mistakes and what they cost
With the same illustrative estimates, a 50% chance of a win by 4 or more and 7.5% of exactly 3:
| Mistake | What it costs | The fix |
|---|---|---|
| Taking the higher price on a different line | -3.5 at $1.93 instead of -3 at $1.85: 0.50 x 1.93 - 1 = -3.5c per $1, against 0.50 x 1.85 + 0.075 - 1 = 0c | Compare prices on the same line, or value the half point first |
| Paying for a half point across 4 or 5 as if it crossed 3 | About $5 per $100 staked in the -4.5 to -4 example | Value each half point by the margin it crosses |
| Expecting a tie to push a -3.5 bet | A tie is a margin of 0, so the -3.5 side loses the whole stake | Only a line of 0 pushes on a tie |
Pick the line when your opinion is about the margin, and the head to head when it is only about who wins. At -1.5 the two bets differ only when the favourite wins by exactly 1 or the game is tied, so there the choice comes down to price.
Risk: Betting involves risk. Pricing the half point first can stop you overpaying for a line, but your chances are estimates, and the right line at the right price can still lose. See responsible gambling for limits and support.
Comparing NFL lines at different bookmakers
Compare the line as well as the price: -3 at $1.85 with one bookmaker and -3.5 at $1.93 with another are different bets.
B337's Terminal gives each bookmaker its own column on line markets, as well as head to head and totals, and picks out the best available price on each selection. Its sports side covers AFL, NRL, NBA, soccer, tennis and more whenever bookmakers have markets up, and the board carries 40+ bookmakers across racing and sports, though not every bookmaker prices every game. A free account opens a limited view of the Terminal with live odds.
Prices are read on a repeating cycle rather than tick by tick, so check the line and the price with your bookmaker before you bet.
Risk: Betting involves risk. Shopping for lines changes the number and the price you take, not the game itself; a better line still loses whenever the margin goes against it, and losing streaks on line bets are normal. See responsible gambling for limits and support.