MLB betting glossary

The core bets

Moneyline (ML). The primary baseball bet — a straight wager on who wins, no handicap. Priced with odds: favorites pay less than you risk, underdogs pay more. Because MLB games are close, moneylines are where most baseball value lives.

Run line. Baseball's version of the spread, and it's almost always 1.5 runs. The favorite at -1.5 must win by 2+; the underdog at +1.5 covers if they win or lose by exactly 1.

Total (Over/Under). A bet on the combined runs scored by both teams, over or under a posted number (often 7.5–9.5).

First five innings (F5). A bet settled on the score after five innings — a popular way to back a team's starting pitcher without depending on the bullpen.

NRFI / YRFI. "No Run First Inning" / "Yes Run First Inning" — a bet on whether either team scores in the opening frame.

Parlay. Multiple bets combined into one; all legs must win. Bigger payout, much lower probability, and worse expected value.

Prop bet. A wager on something other than the final result — a pitcher's strikeouts, a batter's hits or total bases, etc.

Pricing & the book's edge

Juice / vig. The sportsbook's built-in commission. Standard MLB sides are priced at -110, meaning you risk $110 to win $100. That extra 10% is the vig.

Implied probability. The win rate a price implies. -110 implies about 52.4% — your break-even point. Convert any price with our odds calculator.

Hold. The book's theoretical profit margin on a market once both sides' vig is combined.

Outcomes

Cover. When a team beats the run line — e.g. a -1.5 favorite winning by 2+.

Push. A tie against the number (e.g. you bet the total at Over 8.5 and exactly 8 runs score is a loss, but a whole-number total of 8 landing on 8 is a push). Your stake is returned — no win, no loss.

Listed pitcher. A moneyline bet placed "if the listed starters both pitch." If a team changes its announced starter, the bet is voided and refunded.

Line movement

Opening line. The first number a book posts for a game, usually the morning of (or night before).

Closing line. The final number right before first pitch — considered the market's sharpest estimate.

Closing line value (CLV). Whether you beat the closing number. Consistently getting CLV is the strongest sign you're betting +EV, even during a cold streak.

Steam. A sudden, sharp line move driven by heavy money on one side — often following a confirmed lineup or pitching news.

Action. A bet that stands no matter what — as opposed to a "listed pitcher" bet, an "action" wager holds even if a starting pitcher changes.

Strategy terms

Expected value (EV). The long-run average profit or loss of a bet. Positive EV is the entire goal. See our full explainer.

Unit. Your standard bet size, ideally 1–2% of your bankroll. Results are tracked in units so they're comparable regardless of stake.

Middle. Betting both sides of a game at different numbers so a result landing in between wins both.

Line shopping. Comparing prices across sportsbooks to always take the best available number.