AFL line betting, also called handicap betting, is a bet on a team after a points handicap is applied to the final score. With the favourite at -15.5, a bet on it wins only if the favourite wins by 16 points or more; back the underdog at +15.5 and you win if it loses by 15 or fewer, draws or wins outright.
With illustrative prices, both sides of the main line sit close to even money at about $1.90 each, while the head to head on the same favourite might be $1.42. The line is one of the core markets in AFL betting.
How a -15.5 line settles
Apply the line to the team it is quoted for, then compare the scores: with the favourite at -15.5, subtract 15.5 from its score, or add 15.5 to the underdog's, and see who is ahead.
AFL scores are written as goals, behinds and total: 14.10 (94) means 14 goals and 10 behinds. The AFL's stats glossary counts a goal as 6 points and a behind as 1, so 14 x 6 + 10 = 94. With illustrative prices of $1.90 on each side and a $50 stake:
| Final score, favourite first | Margin | Favourite -15.5 | Underdog +15.5 |
|---|---|---|---|
| 15.12 (102) to 9.8 (62) | Favourite by 40 | Wins, returns $95 | Loses $50 |
| 13.12 (90) to 11.8 (74) | Favourite by 16 | Wins, returns $95 | Loses $50 |
| 13.11 (89) to 11.8 (74) | Favourite by 15 | Loses $50 | Wins, returns $95 |
| 11.9 (75) to 11.8 (74) | Favourite by 1 | Loses $50 | Wins, returns $95 |
| 11.8 (74) to 11.8 (74) | Draw | Loses $50 | Wins, returns $95 |
| 10.8 (68) to 12.10 (82) | Underdog by 14 | Loses $50 | Wins, returns $95 |
A 16-point win clears 15.5 by half a point. One behind fewer and the favourite wins by 15, half a point short, so the underdog's points start carries the bet.
Example: Illustrative prices, not a real game or a current market. Return = stake x price = $50 x 1.90 = $95, of which $45 is profit.
Why most AFL lines carry a half point
A line on a whole number can land exactly. If the favourite is at -15 and wins by 15, neither side has won: that is a push. Depending on the bookmaker's rules the bet is void or the stake is returned, and either way it has no result.
Counted from the AFL's published results for the 2022 to 2026 home-and-away seasons (1,026 matches), each exact final margin from 1 to 20 points came up in about 2.1% of games, split between the two teams. So a line of -15 pushes only when the favourite wins by exactly 15, roughly 1 game in 100, and the half point removes that outcome.
AFL margins also have no key numbers. Scores rise by 1 or 6 points at a time, so a game can finish on almost any margin. In those 1,026 matches the most common margins were 1, 2 and 4 points (30, 29 and 28 games), and none stood far above its neighbours. There is no number where a half point is worth much more than at the numbers either side of it. The half point line entry covers the term across sports, and line betting explained covers lines in other codes.
Alternate lines and how their prices step
Alternate lines, sold as pick your own line by some bookmakers, put the same game at other handicaps, each with its own price. The further the favourite has to win by, the longer the price.
Final margins in 2022 to 2026 had a standard deviation of about 41 points; the spread around a pre-game line is narrower, because the line already accounts for the gap between the teams.
The table assumes margins follow a normal curve centred on the main line (-15.5) with an illustrative spread (standard deviation) of 36 points, and the same 5% shade off the fair price on every line. The chance a line covers is the share of the curve above it: -10.5 covers on a win by 11 or more, the share above 10.5.
| Favourite line | Chance it covers (model) | Fair price | Illustrative price | Step from the line above |
|---|---|---|---|---|
| -5.5 | 60.9% | $1.64 | $1.56 | none |
| -10.5 | 55.5% | $1.80 | $1.71 | +$0.15 |
| -15.5 (main line) | 50.0% | $2.00 | $1.90 | +$0.19 |
| -20.5 | 44.5% | $2.25 | $2.14 | +$0.24 |
| -25.5 | 39.1% | $2.56 | $2.43 | +$0.29 |
| -30.5 | 33.8% | $2.96 | $2.81 | +$0.38 |
Fair price = 1 / chance and the illustrative price = fair price x 0.95, so -10.5 is 1 / 0.555 = $1.80 fair and $1.80 x 0.95 = $1.71. Each point of line moves the chance by about 1.1 percentage points, in line with the measured 1% of games per exact margin for each team. The price steps still grow away from the main line, because a price is 1 divided by a chance.
To check an alternate line, work out its fair price from the main line and see how far below fair the bookmaker's price sits. If the alternates are shaded harder than the main line, the difference is what the extra choice costs.
Risk: Betting involves risk. The 36-point spread is an illustrative assumption rather than a measured property of any game, and a price above a model's fair price can still lose. See responsible gambling for limits and support.
Why AFL lines move before the game
A line moves when the market's view of the margin changes, and the biggest scheduled change is the team list. Under the AFL Regulations (11 February 2026 version), clubs lodge Friday and Saturday teams with the AFL by 5:45 pm Melbourne time on the Thursday. Until the match starts, they can still swap a named player for a listed emergency if he cannot play through injury, illness or personal circumstances. AFL team selections and betting covers the full timetable.
- A key player named or left out moves the line by however many points the market thinks he is worth, and a late out on match day can move it again.
- When the market expects rain or strong wind to cut scoring, it moves the total first (AFL total points betting measures how games noted as wet have scored). With fewer points expected there is less room for a big lead, so the line can come in towards the underdog too. Treat that as a direction to watch, not a fixed conversion.
- A line can also move on the bets a bookmaker takes, with no news at all.
A bookmaker may move the price before it moves the line. A shift from $1.90 to $1.80 on the same -15.5 changes the implied chance from 52.6% to 55.6%, about 2.9 percentage points, or roughly 2.7 points of line at 1.1 percentage points a point.
The Interactive Gambling Act 2001 allows online betting on a sporting event only before the event has begun (s 8A(3) and s 10B), and only from a provider licensed under an Australian state or territory law (s 15AA). So the last line you can take online is the one posted before the game starts.
Line or head to head on the same game
The line and the head to head ask two questions about one margin. With illustrative prices:
| Bet | Price | Implied chance (1 / price) | Wins when |
|---|---|---|---|
| Favourite head to head | $1.42 | 70.4% | Favourite wins by any margin |
| Favourite -15.5 | $1.90 | 52.6% | Favourite wins by 16 or more |
| Underdog +15.5 | $1.90 | 52.6% | Underdog loses by 15 or fewer, draws or wins |
| Underdog head to head | $2.85 | 35.1% | Underdog wins |
The gap between the favourite's head to head and its line is a 1 to 15 point favourite win, where the head to head wins and the line loses. In the model from the alternate lines table, that band holds about 16% of results.
To choose, compare both prices with your own estimate. Say you rate the favourite a 69% chance to win and a 54% chance to win by 16 or more (illustrative). Expected value per $1 = chance x price - 1:
- head to head: 0.69 x 1.42 - 1 = -0.020, an expected loss of about 2.0c per $1 on average
- line: 0.54 x 1.90 - 1 = +0.026, an expected gain of about 2.6c per $1 on average, if the 54% is right
One view of the game gives two answers, because the $1.42 asks for a 70.4% chance and your estimate is 69%. Use the line when your view is about the size of the win, or when the head to head is too short for the chance you give it. Use the head to head when your view is simply that a team wins.
A draw also splits the two. The line bet has a result (the team receiving points wins), while the head to head goes to the bookmaker's draw rule. Draws were 10 of the 1,026 home-and-away matches from 2022 to 2026, about 1 in 100, and AFL draw rules sets out how they settle.
Risk: Betting involves risk. An estimate of 54% is a judgement, not a known chance, and a bet with a positive expected value can still lose, and often does. See responsible gambling for limits and support.
Edge cases: finals and stopped games
A final cannot end level. Regulation 2.8 of the AFL Regulations sends a tied final into two periods of three minutes plus stoppages, repeated until there is a winner. Whether a line bet is settled on the score after extra time or at the end of normal time is in your bookmaker's terms, so read them before you bet on a final.
Under Regulation 33.2, a home-and-away match that cannot restart within 60 minutes (or another period the AFL sets) is deemed a draw if play has not reached half time. If it has, the result stands at the score when play stopped. Your bet may follow that official result or be void under the bookmaker's own rules, so the two can differ.
Mistakes that cost money on AFL lines
- Reading the sign backwards. Minus gives points and plus receives them, so backing -15.5 when you meant +15.5 turns a 1 to 15 point favourite win from a winning bet into a losing one.
- Comparing prices without comparing lines. A longer price on a harder line can be the worse bet, because each point of line is worth about 1.1 percentage points of chance.
- Treating a whole-number line as a half point. A 15-point win pushes -15 and loses -15.5.
- Assuming two lines at two bookmakers will both win. Backing -14.5 at one bookmaker and +17.5 at another wins both bets only on a favourite win by 15, 16 or 17. A middle loses on most results by design, and a middle only works if every bet is accepted at the price shown; see AFL line middles and middle betting in Australia.
Comparing AFL lines across bookmakers
Bookmakers do not always agree: one can post -14.5 while another has -16.5, or the same line at $1.87 and $1.95. At about 1.1 percentage points of chance per point, a line one point better at the same $1.90 returns 51.1% x 1.90 = 0.971 per $1 against 50.0% x 1.90 = 0.950, roughly 2% more.
A longer price can also hide a worse line. With illustrative prices, $1.95 at -17.5 looks better than $1.90 at -15.5, but in the model the extra 2 points cut the chance to 47.8%. That returns 0.478 x 1.95 = 0.932 against 0.500 x 1.90 = 0.950, so the shorter price is the better bet by about 1.8c per $1. Line shopping covers the habit, and AFL margin betting shows how the same line prices the margin bands.
The B337 Terminal compares prices from 40+ bookmakers across racing and sports. For AFL it lines up head to head, line and total prices side by side, with price history (flucs), so you can see where each bookmaker's line sits and how it has moved. Not every bookmaker prices every game, and prices are read on a repeating cycle rather than tick by tick, so confirm the price in your bookmaker account before you bet. A free account opens a limited view of the Terminal with live odds.
Risk: Betting involves risk. A better line improves the price you get, not the result, and there is no guarantee of profit. Prices can change before your bet is accepted. See responsible gambling for limits and support.