How Often Does a Run Score in the First Inning? We Analyzed 61,579 MLB Games to Find Out

The total comes out to 61,579 games. And what we found might change the way you think about first inning betting for the rest of your life.

Out of 61,579 MLB games played since 2000, exactly 31,677 of them featured at least one run scored in the first inning.

That comes out to 51.44 percent.

Let that number sink in for a second. The majority of MLB games over the last quarter century have had a run cross the plate before the second inning even starts. Not by a landslide, but consistently, reliably, more often than not.

On the flip side, 29,902 games went scoreless through the first inning, working out to 48.56 percent. If you're someone who likes betting on a scoreless first inning, you're betting on something that happens less than half the time across a massive 26-year sample.

We want to be completely transparent about how we arrived at these numbers, because accuracy is everything when you're making claims backed by data.

The Retrosheet game logs include official linescore data for every MLB game. We checked whether either the visiting team or the home team scored at least one run in the first inning. If either team scored, that game counted as a "yes." If both teams were held scoreless through the entire first inning, it counted as a "no."

There is no modeling here. No projections. No assumptions. No extrapolation from a handful of games. This is simply counting what actually happened in every MLB game over 26 consecutive seasons. The 51.44 percent first inning run percentage is not a prediction or an estimate. It is a verified historical fact based on the complete population of games.

When other sites throw around numbers like "about 50 percent" or "approximately 49 percent" without citing a source, a sample size, or a methodology, you should be skeptical. We're giving you the exact number, the exact dataset, and the exact method. Take it to the bank.

Here's where this gets really interesting for anyone who bets on baseball.

When sportsbooks post their first inning run lines, the "no run scored" side is almost always priced as the favorite. That means if you want to bet that a run will score in the first inning, you're typically getting plus money or close to even money. The books are essentially telling you that a scoreless first inning is the more likely outcome.

But 26 years of data says the opposite is true. A run scoring in the first inning is actually the more likely outcome, and it has been for over two decades running.

Think about what that means mathematically. The breakeven point for a bet that hits 51.44 percent of the time is approximately minus 106. That means any time you're getting better than minus 106 on a run being scored in the first inning, you're looking at a situation where the math is theoretically working in your favor.

And in many games, particularly when the game total is average or below average, sportsbooks are offering even money or plus money on the first inning run side. That's potential value sitting right there on the board during every single day of the MLB season.

To put some real numbers to it, here are a couple of examples from actual sportsbook pricing. A game between two mid-tier pitching staffs with a total around 7.5 might be priced at plus 100 for a first inning run and minus 135 for no first inning run. A game between two weaker pitching staffs with a total around 9.5 might flip entirely, with the first inning run side priced around minus 155 and the no run side at plus 115.

The point is that the average pricing across all games tends to give the first inning run side favorable or near-even odds, despite the fact that first inning runs happen more often than not.

This is a fair question and it deserves an honest answer. Sportsbooks are not in the business of giving away money, so why would they consistently shade the line toward the no run side?

A few factors are at play here.

The "no run first inning" bet appeals to a certain type of recreational bettor who loves the quick sweat. The bet settles in minutes, and there's something satisfying about watching two pitchers cruise through a clean first inning. Books know this side attracts heavy casual action, so they shade the line to balance their exposure.

The pricing also varies enormously from game to game. When two aces are on the mound, the no run side might be minus 160 or heavier. When two back-end starters are facing loaded lineups, the first inning run side can actually become the favorite. But on average, the no run side tends to be priced as the favorite across the full slate, even though our data shows it's the less likely outcome historically.

There's also the vig to consider. Even when the math favors the first inning run side, sportsbooks build their commission into both sides of the line. A small theoretical edge can be eaten up by the juice if you're not disciplined about the prices you're taking. That's why this isn't just about knowing the 51.44 percent number. It's about knowing when the pricing gives you enough margin to overcome the vig. This is exactly the type of structural market inefficiency we explore across all prop categories on this site.

Understanding why runs score so frequently in the first inning helps paint the full picture.

The most obvious reason is lineup construction. Both teams send their best hitters to the plate in the first inning. The leadoff hitter, the two and three hole guys, and potentially the cleanup hitter all get guaranteed at-bats in the opening frame. That's eight of the best hitters in the game stepping into the box before the second inning even begins.

Starting pitchers also tend to be at their most vulnerable in the first inning. They're finding their rhythm, adjusting to the mound conditions, and settling into the game. Some pitchers are notorious for giving up early runs before locking in. The adrenaline of the first inning can work against a starter just as easily as it works for the hitters.

Ballpark factors play a role too. Certain parks are significantly more conducive to first inning scoring than others. High-altitude parks, hitter-friendly dimensions, and weather conditions like wind blowing out all contribute to elevated first inning run rates in specific venues. These are the kinds of filters that can push the first inning scoring rate well above the 51.44 percent average.

• Lineup construction: Both teams send their best hitters to the plate in the first inning, guaranteeing eight elite at-bats before the second inning starts.
• Pitcher vulnerability: Starters are at their most vulnerable in the first inning while finding their rhythm and adjusting to mound conditions.
• Ballpark effects: High-altitude parks, hitter-friendly dimensions, and weather conditions push first inning run rates well above average at specific venues.
• Division familiarity: Day games, division rivalries, and extensive hitter-pitcher familiarity can all influence first inning scoring probability.
• Late-season factors: Bullpen fatigue forces teams to start less experienced arms later in the season, increasing early-inning vulnerability.

While the overall 51.44 percent first inning run rate is the foundational insight, the real money is in filtering.

Not all games are created equal. Some matchups, some parks, and some situations push the first inning scoring rate well above the average. When you can identify those spots and still get favorable odds from the sportsbook, your edge multiplies significantly.

Think about it this way. If you can find a subset of games where the first inning run percentage jumps to 58 or 60 percent, but the books are still pricing the run side at plus money because the pitchers have recognizable names, you're looking at a meaningful edge. That kind of targeted analysis is exactly what this dataset was built for, and it's something we'll be diving deeper into in future articles here at MLBProps.com.

We analyzed all 61,579 MLB games played from the 2000 season through 2025 using official Retrosheet game logs. A run scored in the first inning in 31,677 of those games, which is 51.44 percent of the time. A scoreless first inning occurred in 29,902 games, or 48.56 percent.

Those numbers are not estimates, projections, or models. They are verified facts derived from 26 complete seasons of official MLB data.

The first inning run market is one of the most popular prop bets in all of baseball, and 26 years of data suggests that the "yes, a run will score" side has been the mathematically correct outcome more often than not for a quarter of a century. Whether that translates directly into a profitable betting strategy depends on the specific odds you're getting game by game. But the foundational numbers are crystal clear, and they tell a story that most bettors and most sportsbooks would rather you not think too hard about.

The next time someone tells you that most games start with a scoreless first inning, you can tell them they're wrong. And you've got 61,579 games worth of proof to back it up.

This analysis was conducted using official Retrosheet game log data covering every MLB game from 2000 through 2025. All figures are 100% verified against the complete historical record. MLBProps.com is committed to original, data-driven analysis. We don't guess. We count.