Line betting — also called point-spread, handicap, or simply "the line" — is the cleanest value market available across team sports. It applies a points handicap to one side so the market settles on prices close to even money. For Australian punters, mastering the spread means understanding both the maths (vig, half-points, key numbers) and the workflow (shopping across books, logging closing lines, sizing correctly). This guide covers all of it. Read the foundation in positive EV betting first if you are new to expected value.
How line betting works
A spread applies a handicap to balance the two teams. If Geelong are -23.5 against Hawthorn, they must win by 24 or more to cover. Hawthorn at +23.5 wins the bet if they lose by 23 or fewer, or win outright. The half-point removes the possibility of a push (tie); whole-number lines (-23.0) can push and refund.
Prices on either side of the spread are usually close to even money — typically $1.91 or $1.92 in Australia. That 4-5% vig on each side determines your break-even rate. Your edge in spread betting comes from two sources: a more accurate probability estimate than the market, and better execution across operators.
Spreads are quoted with a number and a price. -3.5 at $1.91 is different from -3.5 at $1.95 (less vig) and different from -3.0 at $1.91 (pushes possible). Always read both the line and the price together.
Spread structure across sports
AFL and NRL
Australian books post AFL "line" markets all season. Spreads range from -1.5 to -60.5 in AFL and -1.5 to -24.5 in NRL. AFL doesn't have strong key numbers because scoring is continuous; NRL has weak key numbers around 6, 8, and 12 (try plus conversion combinations).
NFL
NFL spreads are the most studied and the most key-number-sensitive market in sport. The big NFL numbers are 3, 7, and 10 because of the 3-point field goal and 7-point touchdown plus extra point. A line moving from -3 to -3.5 has dramatically different value because of the high frequency of 3-point margins.
NBA
NBA spreads are quoted in half-point increments and rarely sit on integer values for long because basketball margins distribute more continuously. Still, 3, 5, and 7 carry slight key-number weight.
Soccer
Soccer uses Asian handicaps with quarter-point increments (-0.25, -0.75) that split the stake between two lines and refund half on certain pushes. Asian markets are usually lower vig than 1X2 markets.
Vig, break-even rate and price variants
At $1.91 both sides, the book holds ~4.5%. Your break-even rate is ~52.4% — you need to win 52.4 bets out of every 100 to break even. A small edge of 1-2 percentage points compounds into meaningful profit over hundreds of bets.
Reduced-vig books exist. Pinnacle (offshore) prices many spreads at $1.95/$1.95 (break-even ~51.3%). Bet365 and Pointsbet occasionally promote $1.95 lines on featured matches. A consistent 1.5 percentage-point reduction in vig is the difference between marginal loss and consistent profit.
See devigging odds for how to back out implied fair probabilities from any two-sided spread market.
Key numbers and half-point value
Key numbers are margins of victory that occur more often than the distribution would suggest. In NFL, ~15% of games end on a 3-point margin and ~10% on 7. That makes the difference between -3 and -3.5 worth as much as 25-30 cents in price. Buying a half-point from -3.5 to -3.0 for $2.00 instead of $1.91 is rarely correct because the implied price of that half-point is much higher than the cost.
In NRL the spread structure is weaker but 8 (try + conversion + try) and 12 (two converted tries) carry some weight. AFL has effectively no key numbers — scoring distributes too smoothly.
In NBA, 3, 5, and 7 carry small weight from late-game three-pointer dynamics. Soccer key numbers are 1 and 2 goal margins given the typical scoreline distribution.
Practical rule: never cross a key number for a worse price. Always pay to cross a key number in the right direction. If two books offer -3.0 at $1.91 and -3.5 at $1.83, the -3.0 is almost certainly the better bet because of the 3-point push frequency.
Cross-book line shopping workflow
Line shopping is the single highest-EV habit available to spread bettors. Australian operators (Sportsbet, TAB, Ladbrokes, Neds, BlueBet, Pointsbet, bet365) regularly post spreads that differ by half a point or by 5-10 cents on price.
A simple workflow:
- Decide your model spread (your true number) before opening any book.
- Open all your books in tabs.
- Compare both the line and the price. Compute the EV of each book's offer against your model.
- Execute at the best combination. Re-check just before kickoff for late moves.
Without shopping, you concede 2-4% per bet against a sharp price. With shopping, you capture half or more of that back, before any modelling edge is layered in.
Middles and arbitrage
When books diverge on spread points, selective middles become available. If Sportsbet have Geelong -23.5 and Ladbrokes have Hawthorn +25.5, betting both creates a "middle" — if Geelong win by exactly 24 or 25, both bets win. Otherwise one wins and one loses, costing you only the vig.
Middle betting requires capital across multiple books and patience. Most middle opportunities are 2-5 point gaps with low hit rates (1-3%), but the asymmetric payoff (you risk ~5% per side to win ~95% on the rare double-win) makes them profitable in aggregate when sized correctly.
See middle betting explained for a deeper treatment and worked examples.
Closing line value as scoreboard
Closing line value (CLV) is the difference between your price/line at bet placement and the final market price/line at kickoff. Positive CLV over hundreds of bets is the only reliable indicator that your process is generating real edge before variance washes out.
Log every spread bet with: stake, line, price, book, your model line, closing line, closing price. Review monthly. If CLV is positive and your win rate is below expectation, you have a process edge masked by variance — keep going. If CLV is flat or negative, your model or shopping discipline needs work.
Full details in closing line value explained.
Bankroll approach and staking
Keep spread staking stable with conservative Kelly fractions (0.25 to 0.5 Kelly) and avoid tilt-based scaling. Typical unit sizing for spread bettors is 1-2% of bankroll per bet at near-fair pricing. Larger units are inappropriate because the variance is high even with a true edge.
Track running bankroll, not session-by-session. A "bad day" of three losing spreads is within normal variance for any disciplined bettor. Avoid doubling up to chase losses — the maths of geometric drawdown makes recovery progressively harder.
Cross-reference variance and bankroll volatility to understand why even +EV spread bettors face frequent 20-40 unit drawdowns.
In-play and alternative lines
In-play spreads update continuously and the vig is wider (often 6-8%). They are useful for catching overreactions but require a faster decision cycle. Pre-set click limits and stop-loss rules before opening in-play.
Alternative lines (buying or selling points) are offered across most Australian books. Buying a half-point typically costs 10-25 cents in price. The implied cost of that half-point should be compared against the historical push frequency at that number. Buying across key numbers (e.g. through 3 in NFL) is usually overpriced; buying across non-key numbers (4 to 4.5 in NFL) is usually underpriced.
Common mistakes
- Chasing stale line moves. The market moved for a reason; jumping in after the move is paying tax.
- Betting one account only. Single-book bettors give up 2-4% per bet on average from not shopping.
- Overusing multis. Vig compounds and key-number value evaporates across legs.
- Buying half-points carelessly. Crossing a key number requires specific price tolerance; crossing a non-key number rarely justifies the cost.
- Ignoring vig variance. A $1.95 line at one book and a $1.85 line at another are very different bets despite the same spread number.
- No CLV log. Without recording closing prices you cannot diagnose whether bad results are variance or process failure.
Operations checklist
- Maintain accounts at five or more Australian operators plus Betfair Exchange.
- Pre-decide your model line before opening any book.
- Record stake, line, price, closing line, and closing price for every bet.
- Review CLV monthly by sport and by market.
- Use 1-2% unit sizing on standard spreads; reduce for in-play.
- Never cross a key number for a worse price.
- Treat middles as a separate workflow with their own bankroll cap.