Run line betting is line betting on a baseball game, and the line is usually 1.5 runs. The favourite at -1.5 has to win by two runs or more, while the underdog at +1.5 wins your bet if it wins outright or loses by exactly one run. Because the line usually stays at 1.5, the price on each side is what changes from game to game.
That one-run gap decides a lot of bets. Of the 2,430 MLB regular-season games in 2025, 714 (29.4%) ended one run apart, and every one of them paid the +1.5 side. US coverage uses the same name for this market and calls the head to head the moneyline; US sports betting from Australia translates the rest.
How a -1.5 run line bet is settled
Settling a run line takes one subtraction: deduct 1.5 runs from the favourite's total, and if it still leads, -1.5 wins; if not, +1.5 does. Half a run cannot be scored, so a 1.5 line never pushes.
With illustrative prices of $2.20 on the favourite at -1.5 and $1.72 on the underdog at +1.5, here is $40 on each side, settled on five possible results:
| Result, favourite's runs first | Winning margin | -1.5 at $2.20 | +1.5 at $1.72 |
|---|---|---|---|
| 6-2 | Favourite by 4 | Wins, returns $88.00 | Loses $40 |
| 5-3 | Favourite by 2 | Wins, returns $88.00 | Loses $40 |
| 4-3 | Favourite by 1 | Loses $40 | Wins, returns $68.80 |
| 3-2 in 10 innings | Favourite by 1 | Loses $40 | Wins, returns $68.80 |
| 2-5 | Underdog by 3 | Loses $40 | Wins, returns $68.80 |
Example: Illustrative prices, not a real game. A winning -1.5 bet returns 40 x 2.20 = $88.00, a $48.00 profit; a winning +1.5 bet returns 40 x 1.72 = $68.80, a $28.80 profit. Add the implied chances and the book comes to 1 / 2.20 + 1 / 1.72 = 0.4545 + 0.5814 = 103.6%.
The underdog side wins three of the five rows, two of them games its team lost: +1.5 is right more often and pays less, -1.5 is right less often and pays more. Line betting explained covers how a points start works in every sport.
In NSW, the Bookmaker Declared Betting Events Betting Rules (read October 2026) make a half-point start the default for bookmakers authorised there, with extra time counted, unless you agree otherwise when you bet (clause 5.1.3). Bookmakers licensed elsewhere write their own terms.
Why the run line stays at 1.5
The baseball run line stays at 1.5 for most games because runs are scarce, about 8.9 a game between the two teams in 2025, and finishes bunch up at one run. Moving the line a whole run would flip the result of a big slice of games, so where most sports move the line, baseball moves the price.
The 2025 regular season, from 18 March to 28 September, shows the shape. No game ended tied:
| Winning margin | Games | Share of 2,430 |
|---|---|---|
| 1 run | 714 | 29.4% |
| 2 runs | 413 | 17.0% |
| 3 runs | 312 | 12.8% |
| 4 runs | 292 | 12.0% |
| 5 runs or more | 699 | 28.8% |
Every winner in the first row lost a -1.5 bet. So a team has to win often, and by enough, before its -1.5 price drops below even money ($2.00). With illustrative prices, a team at $1.55 on the head to head might be $2.10 at -1.5, and one at $1.80 might be $2.55. The counts come from MLB's 2025 standings and box scores.
Home favourites and the bottom of the ninth
Two rules in the 2026 Official Baseball Rules cap a home team's margin. A home team that leads after eight and a half innings does not bat in the ninth (Rule 7.01(a) and 7.01(e)(1)). And when the home team scores the winning run in the ninth or an extra inning, the game ends the moment that run crosses the plate (Rule 7.01(e)(3)). The one exception is a home run out of the park, which brings in every runner on base.
So a home side that leads 4-3 after the top of the ninth wins 4-3. A visiting side that leads 4-3 after eight innings bats again in the ninth and can add to its lead. The 2025 split:
| 2025 regular season | Home teams | Away teams |
|---|---|---|
| Games won | 1,319 | 1,111 |
| Won by one run | 453 (34.3%) | 261 (23.5%) |
| Won by two or more, covering -1.5 | 866 (65.7%) | 850 (76.5%) |
Of the home wins, 222 came in the home team's last turn at bat after it started that turn level or behind, and 200 of those were by a single run.
Give a home favourite and an away favourite the same illustrative 60% chance to win, use these league shares as a rough guide, and their -1.5 bets are worth different prices:
- away favourite: 0.60 x 0.765 = 45.9%, a fair price of 1 / 0.459 = $2.18
- home favourite: 0.60 x 0.657 = 39.4%, a fair price of 1 / 0.394 = $2.54
Treat these league shares as a starting point, not a measure of any one team.
Run line or head to head: a worked comparison
The head to head asks only who wins; the run line moves every one-run result to the underdog's side. To choose, split your win chance into wins by one run and wins by two or more.
With illustrative prices, Team A is the home favourite at $1.63 on the head to head and $2.45 at -1.5, and Team B is $2.35 on the head to head and $1.58 at +1.5. You rate Team A a 60% chance to win and expect 70% of its wins to come by two runs or more, above the 65.7% home average, so -1.5 is 0.60 x 0.70 = 42.0%.
| Bet | Price | Your chance it wins | Value per $1 staked |
|---|---|---|---|
| Team A head to head | $1.63 | 60.0% | 0.600 x 1.63 - 1 = -2.2c |
| Team A -1.5 | $2.45 | 42.0% | 0.420 x 2.45 - 1 = +2.9c |
| Team B head to head | $2.35 | 40.0% | 0.400 x 2.35 - 1 = -6.0c |
| Team B +1.5 | $1.58 | 58.0% | 0.580 x 1.58 - 1 = -8.4c |
On these estimates -1.5 is the only bet worth more than it costs, and only just. It breaks even when the share of Team A's wins that come by two or more is 1 / (0.60 x 2.45) = 68.0%. At 66% the same bet is worth 0.60 x 0.66 x 2.45 - 1 = -3.0c per $1, so four percentage points of judgement turn a small edge into a loss.
The fair odds calculator takes the margin out of both run line prices, which gives the bookmaker's own view to compare with yours.
Risk: Betting involves risk. The 60% and 70% are illustrative judgements, not known chances, and at $2.45 the -1.5 bet loses most of the time even when its expected value is positive. See responsible gambling for limits and support.
Extra innings and the run line
A full-game run line counts extra innings under the common rule type, so a game level after nine is live for both sides. During the regular season, every half-inning after the ninth begins with a runner placed on second base (Rule 7.01(b)(2)). In the postseason, from the Wild Card Series to the World Series, it does not (Rule 7.02(g)).
The walk-off rule follows the game into extras. The visitors bat first in each extra inning and can score two or three, while the home team stops the moment it goes ahead. In 2025, 209 regular-season games (8.6%) went past nine innings:
| Extra-inning games, 2025 | Won by one run | Won by two or more |
|---|---|---|
| Home team won (110) | 96 | 14 |
| Away team won (99) | 49 | 50 |
Once a game reached the 10th, a home -1.5 bet covered in 14 of the 209 games (6.7%) and an away -1.5 bet in 50 (23.9%). For the home favourite at -1.5, a tie after nine is close to a lost bet.
Example: Illustrative price. You have $30 on the home team at +1.5, priced $1.70. It is 4-4 after nine, the visitors score twice in the 10th and the home team gets one back, losing 5-6. A one-run loss covers +1.5, so the bet returns 30 x 1.70 = $51.00.
Alternative run lines and the reverse run line
Alternative run lines move the start for a different price, and the reverse run line swaps the usual sides. Availability varies by bookmaker. The common shapes:
| Line | What has to happen | Price compared with the main line |
|---|---|---|
| Favourite -2.5 | Favourite wins by 3 or more | Longer than -1.5 |
| Favourite +1.5 (reverse) | Favourite wins, or loses by 1 | Shorter than its head to head |
| Underdog -1.5 (reverse) | Underdog wins by 2 or more | Longer than its head to head |
Price them from your own estimates. Keep Team A at 60% to win, with 70% of its wins by two or more and 50% by three or more, and rate Team B's wins as 65% by two or more:
- Team A -2.5: 0.60 x 0.50 = 30.0%, a fair price of 1 / 0.30 = $3.33
- Team B -1.5: 0.40 x 0.65 = 26.0%, a fair price of 1 / 0.26 = $3.85
- Team A +1.5: 1 - 0.26 = 74.0%, a fair price of 1 / 0.74 = $1.35
For scale, 70.6% of all 2025 games were won by two runs or more and 53.6% by three or more. Pick your own line covers how alternative prices step away from the main line and what that costs.
Called games, pitcher changes and the first five innings
Three things can stop a run line bet settling the way the final score suggests.
- A called game. Under Rule 7.01(d), a game halted once five innings are complete, or after four and a half with the home side in front, can count as a regulation game. Terms differ on whether a run line stands then; MLB betting from Australia sets out the rule types for rain and postponements.
- A pitcher change. The NSW rule book voids every bet on a game whose nominated starting pitcher does not start, unless agreed otherwise (clause 5.2.11); listed pitchers explained covers the other rule types.
- A first five innings run line. It settles on the score after five innings, so extra innings never reach it, and it can finish level, unlike a completed full game. The first five innings entry explains how those markets treat a tie.
Run line mistakes and what they cost
With the 2025 figures and the illustrative estimates above:
| Mistake | What it costs | The fix |
|---|---|---|
| Reading -1.5 as a cheaper way to back the favourite | Every one-run win is a lost bet: 453 home wins (34.3%) and 261 away wins (23.5%) in 2025 | Split your win chance into one-run and bigger wins first |
| Paying the same -1.5 price for a home favourite as an away one | At a 60% win chance, $2.30 on the home side is worth 0.394 x 2.30 - 1 = -9.4c per $1 | Check which team bats last |
| Expecting a tie after nine to void the bet | The game plays on, and home -1.5 covered in only 14 of 209 extra-inning games | Read the run line as a full-game bet |
Comparing run line prices
Check the line before the price: $3.20 at -2.5 is a different bet from $2.40 at -1.5, not a better one. B337's Terminal sets out each bookmaker's head to head, line and total prices for a game in their own columns, with the best available price on each selection picked out. Its sports board covers AFL, NRL, NBA, soccer, tennis and more whenever bookmakers have markets up. The Terminal shows prices from 40+ bookmakers across racing and sports, though not every bookmaker prices every game.
Prices are read on a repeating cycle, not tick by tick, so confirm the price, the line and the pitcher rule 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 price changes what a winning bet pays, not how often a team covers, and a run line backer can lose several bets in a row on one-run games. See responsible gambling for limits and support.