JUMP TO:
- Why understanding MLB betting terms matters
- Core MLB betting terms every fan should know
- Baseball-specific betting lingo
- Futures and season-long MLB bets
- Advanced betting concepts, explained
- Baseball analytics and betting metrics
- Bankroll and risk management terms
- Common slang and informal betting terms
So, you might want to bet on Major League Baseball. Welcome to the club.
The amount of American sports bettors each year is now estimated in the tens of millions, and it's never been easier to access and place bets on sportsbooks.
New baseball bettors won't succeed if they don't learn the basics, though. And, to know the basics, you need to also know the terms and lingo.
We at AllSportsPeople have assembled a comprehensive MLB betting glossary for beginning bettors to get you started. Scroll down the page to feed your brain.
MORE: Betting glossary — key terms to know for every beginner sports bettor
Why understanding MLB betting terms matters
If you don't know every aspect of how to bet on MLB games and markets, you won't fully understand how to bet with strategy and find value on the betting market. It's vital to learn as much as you can, too, not just the basic terms.
Betting has become a complex science, and sportsbooks profit each year off of bettors who don't also treat it as such. So, before you dive into the deep end of the betting world, learn everything there is to know about it so you can make pools of money.
MORE: The dos and don'ts of bankroll management in sports betting
Core MLB betting terms every fan should know
Moneyline: The simplest ways to bet on a team to win
Moneyline is what's called a "straight-up" bet: Who will win the game? The sportsbooks will weigh the odds to encourage near equal action on both the favorite and underdog.
Run Line: Baseball's version of a point spread
Betting the run line means betting on an MLB game's margin of victory.
By default, it's listed as 1.5 runs in either direction, because winning by one run is merely the straight moneyline bet in baseball.
Over/Under (Totals): Betting on combined runs scored
Sportsbooks list a line, balanced for equal betting activity by vigorish (or "juice"), to wager on whether the two teams in a game will combine to score Over or Under the listed total.
For example, you may see the runs total as 5.5, with Over (-110) and Under (-110).
Favorite vs. Underdog: Understanding plus and minus odds
The favorite, or the side of a bet with a higher probability of winning, will be listed with negative odds.
The underdog, or the side of a bet with the lower probability of winning, will appear alongside positive odds.
Juice or Vig: The sportsbook's built-in commission
The odds that the betting operator uses to facilitate betting on both sides of a market and balance their exposure to the public.
As is the case with sports betting on the whole, shop for lines across multiple sportsbooks to find the most favorable vig for your desired wager.
MORE: What are the differences between betting exchanges and sportsbooks
Baseball-specific betting lingo
First five innings bet (F5)
The F5 bet is an abbreviated moneyline wager that calls for predicting the team that will lead on the scoreboard after five innings.
F5s are alternatives to full-game wagers and are becoming one of the most popular MLB bets. This category allows bettors to remove the volatility of middle- and late-game bullpen meltdowns that might otherwise undo a proper read on a game prediction.
Team totals
The team total market splits the Over/Under into team-specific bets.
This allows MLB bettors to narrow their focus with a singular, more controllable outcome, isolating one lineup-versus-pitcher matchup with a tighter probability.
NRFI/YRFI
Betting on whether a run will be scored in the first inning of a baseball game: NRFI means 'No Run in the First Inning,' while YRFI means 'Yes, a Run will be scored in the First Inning.'
The NRFI/YRFI trend is another hugely popular baseball bet that's surged since sports gambling went live in the US.
The early resolution of this bet speaks to this generation of quick-twitch sports viewers and can be argued to promote further betting on this and other games, due to the rapid end of the bet.
Still, while it's a fun event and technically a 50-50 probability, the NRFI/YRFI bet is highly volatile and one of the least recommended MLB prop bets to make.
Action vs. Listed pitchers (what happens if starters change)
The choice offered by some betting operators to bet on an MLB moneyline when a starting pitcher is scratched ahead of a game's start time.
Betting on "action" means you're betting on the team to win regardless of the starting pitcher. Your bet is active regardless of any changes that happens, but odds may change based on trading team changes on the outlook of your team to win. Locking in moneyline odds for a team who announces a pitching downgrade is much riskier.
If you choose "listed pitcher," your bet is only active if the probable starters listed by the sportsbook start the game for each team. If a change happens, the bet is voided, or deemed "no action." This is the safer option of the two that leaves you with a parachute away from a risky bet.
Pitcher and batter props: Strikeouts, hits, home runs, total bases
MLB bettors can wager on numerous player-specific prop markets, commonly listed with either an Over/Under total or a minimum achievement (for example, 4+ strikeouts for a pitcher). Many popular MLB prop bets include:
- Pitcher strikeouts: How many strikeouts a pitcher records during a start. The more talented a pitcher or the more favorable the opponent lineup matchup is, the higher the Over/Under total or minimum threshold will be.
- Batter hits: Whether a hitter records a base hit in the game. The more highly skilled the batter, the shorter the odds to record a hit. Alternate lines or props include predicting a player to record 2 or more hits in a game.
- Batter home runs: Whether a hitter cranks a home run out of or inside the park. Arguably the most popular bet given its big potential payout, but also, given their improbability, it's the riskiest in-game player prop.
- Batter total bases: A more reasonable batter bet, total base wagers target the category that adds up how many bases are compiled by a batter's singles, doubles, triples, and home runs within a game. (A walk does not count as a total base.) The most popular attack here is to bet on a batter to record 2+ total bases to account for a favorable power, extra-base-hit opportunity.
MORE: Ultimate sports betting checklist to follow
Futures and season-long MLB bets
Futures bets in sports betting are wagers on long-term results at particular milestones, mostly with resolution at the end of a sport's season.
As is the case with stocks and other forward-looking trades, futures betting in general must be carefully planned, especially for bankroll management.
Betting and waiting for the settlement of futures bets ties up money through significant portions of the season, allowing futures bettors to help keep operators flush with handle and exposing your bet to the unforgiving MLB season.
With that approach to tie up as little money as possible in futures, betting on heavy favorites for these categories often doesn't provide the best return on investment. Divvying a particular percentage of your bankroll to futures is best used as midrange-to-longshot sleeper bets, going against the grain to land significant ROI and make the extended process worth it.
MORE: What is a betting unit?
World Series futures
Betting on who will win the MLB championship.
Odds may not flucutate for the heavy favorites (read: Dodgers) for much of the season, and barring significant league happenings, they likely won't provide value or most of the year.
Navigate any names outside the top 10 who could sneak into the playoffs through Wild Card berths and are built to last in the postseason with traits that could include elite starting pitching and a low-strikeout hitting approach.
Division and pennant winners
Betting on who will win each league -- American and National -- and who will win the AL East, AL Central, AL West, NL East, NL Central, and/or NL West.
Apply a strategy similar to World Series futures: Target undervalued teams with upside and a realistic path to winning the division.
The most ROI in betting heavy favorites will come from a feature that not every sports betting site allows: Some betting apps, including FanDuel Sportsbook, will allow you to parlay pennant and/or division winners for even bigger payout potential.
Win totals
Betting on how many wins a team will record during the season.
Betting MLB win totals involves adept timing and a read of the market, which is often mispriced depending on current events, past performance, and projections.
Player awards — MVP, Cy Young, Rookie of the Year futures
Betting futures markets on the winner in both the American and National League for MVP (Most Valuable Player), Cy Young (Top Pitcher), and Rookie of the Year.
Again for each award, look for upside for players who could be on the upswing but are priced at more of a longshot line than they should be.
MORE: Complete guide to betting on MLB
Advanced betting concepts, explained
Implied probability
The conversion of betting odds (American, fractional, or decimal) into a percentage that a side of a bet will win based on sportsbook lines.
This is reflected in the juice (vigorish) surrounding sides of a bet.
For instance, -100 or +100 are true 50-50 odds. Most two-sided markets are listed with -110, which, to the detriment of the bettor, implies 52.4% odds that actually reflects a tax from the sportsbook.
Here's a table for reference:
| American Moneyline | Implied Probability |
| -10000 | 99% |
| -500 | 83.3% |
| -450 | 81.8% |
| -400 | 80.0% |
| -350 | 77.8% |
| -333.3 | 76.9% |
| -300 | 75.0% |
| -275 | 73.3% |
| -250 | 71.4% |
| -225 | 69.2% |
| -200 | 66.7% |
| -187.5 | 65.2% |
| -175 | 63.6% |
| -162.5 | 61.9% |
| -150 | 60.0% |
| -137.5 | 57.9% |
| -125 | 55.6% |
| -120 | 54.5% |
| -110 | 52.4% |
| +100 | 50.0% |
| +105 | 48.8% |
| +110 | 47.6% |
| +115 | 46.5% |
| +120 | 45.5% |
| +125 | 44.4% |
| +137.5 | 42.1% |
| +140 | 41.7% |
| +150 | 40.0% |
| +160 | 38.5% |
| +162.5 | 38.1% |
| +175 | 36.4% |
| +180 | 35.7% |
| +187.5 | 34.8% |
| +200 | 33.3% |
| +220 | 31.2% |
| +225 | 30.8% |
| +240 | 29.4% |
| +250 | 28.6% |
| +260 | 27.8% |
| +275 | 26.7% |
| +300 | 25.0% |
| +320 | 23.8% |
| +333.3 | 23.1% |
| +350 | 22.2% |
| +400 | 20.0% |
| +450 | 18.2% |
| +500 | 16.7% |
| +550 | 15.4% |
| +600 | 14.3% |
| +650 | 13.3% |
| +700 | 12.5% |
| +750 | 11.8% |
| +800 | 11.1% |
| +900 | 10.0% |
| +1000 | 9.1% |
| +1100 | 8.3% |
| +1200 | 7.7% |
| +1300 | 7.1% |
| +1400 | 6.7% |
| +1500 | 6.2% |
| +1600 | 5.9% |
| +1800 | 5.3% |
| +2000 | 4.8% |
| +2500 | 3.8% |
| +3300 | 2.9% |
| +5000 | 2.0% |
| +6600 | 1.5% |
| +10000 | 1.0% |
| +100000 | 0.1% |
Line movement
How an event or market's odds change before the closing of betting.
Odds changes happen depending on the sportsbook's trading team, public and "sharps" action, and conditions that directly impact the market, including player injuries, weather conditions, roster reconstruction, and more.
Given how often and rapidly the juice and lines can fluctuate, bettors should act swiftly to submit a bet at a sportsbook app if they have an advantageous angle and a +EV line.
Steam moves
Sudden, significant moves in odds prompted by large bets placed by sharps.
Often spurred by inside information or a vulnerability found in the trading schematics for an event, steam movement will often draw huge money along with it in that direction. It's best to be as early as possible if you identify these steam moves, so you can gain the best ROI and closing line value (more on these below) and beat the rush.
Be careful, though: Sometimes to avoid being detected by sportsbooks and, in turn, limited, teams of sharps sometimes commit "fake steam moves," throwing money at a side they don't want to then place a major bet in the other direction at improved odds.
Closing line value (CLV)
CLV represents the difference between the odds placed by your bet compared to the "closing" of the betting market when the event or market locks.
For instance, if you place a bet on the Yankees run line of -1.5 with (+200) juice, and the line eventually closes at -1.5 (+110), you've achieved positive CLV.
Consistently gaining positive CLV does not guarantee consistent betting success. Many factors could go into line movement that could make CLV irrelevant, including injuries, weather conditions, and other circumstances out of our control -- including simple luck and the innately random nature of sports.
However, showing the instincts to identify when to take advantage of trading trends goes a long way toward becoming a more advanced bettor.
Expected value (EV)
When a sportsbook's betting market offers more favorable potential winnings than the true probability of the outcome, according to betting models.
Subjectivity in market projections will prompt caution, but plays into identifying
Gaining positive expected value (+EV) is much more crucial to your long-term success than closing line value, though the two working together produces the best results when applied correctly.
MORE: 10 common betting mistakes to avoid
Baseball analytics and betting metrics
Isolated betting games and events can present a potentially profitable angle based on advanced MLB metrics, though they should be used with care and not as a primary reason to place a wager.
These statistics are more season-long and long-term indicators of potential advantages and disadvantages that should be infused into your research.
WAR (wins above replacement)
A statistic that estimates an MLB player's true value by measuring how many wins he would add to a team, compared to a replacement-level player.
There is no universally accepted formula, but the concept exists in different forms for some of baseball's leading stats outlets, including Fangraphs (fWAR), Baseball Reference (bWAR/rWAR), and Baseball Prospectus (WARP).
These measuring sticks can be used for finding vulnerabilities in futures markets, if a sportsbook undervalues or overvalues a player's worth to a team that's reflected in a bettable market.
FIP (fielding independent pitching ERA)
A SABR stat rating that aims to judge a pitcher only by things he has the most control over, specifically strikeouts, walks, hit batters, and home runs.
This isolation of pitchers' direct contributions attempts to diminish or remove the impact on his ERA by any bad in-play luck, poor defense, or park factors, in the effort to more accurately rate pitchers on a more equal baseline.
The lower the FIP, the better, just as the case with ERA.
While FIP doesn't necessarily apply directly or successfully to everyday MLB betting action on games, futures and season-long MLB prop bettors could identify buying opportunities if sportsbook trading teams underrate or overrate teams or players who post extreme FIPs on either side of what's expected.
BABIP (batting average on balls in play)
The batting average (hits / at-bats) of a hitter on contact for batted-ball events.
BABIP does not include strikeouts, walks, home runs, and sacrifice bunts (sacrifice flies are included because a fielder can make a play on them).
A batter can carry a relative history of high or low BABIPs, depending on hitting style, but the statistic remains erratic year-to-year dependent on countless variables, including the hitter's exit velocity, groundball-to-flyball tendencies, speed, defensive alignments, and simple pure luck.
BABIP is not a consistent day-to-day attribute to use in MLB betting but sometimes can inform decisions as a supplemental piece of a statistical puzzle.
XFIP, xwOBA, barrel rate — advanced metrics for props and futures
A quick definition of these stats:
- xFIP: Expected fielding independent pitching
- xwOBA: Expected weighted on-base average
- Barrel rate: The percentage at which a batter's contact his
These shouldn't necessarily apply as a required day-to-day implementation for betting, but they could act as a component in single-game player performance as part of a more comprehensive picture of small-sample-size performance. (Don't bank on any particular stat for short-term success.)
For longer-term betting intent, however, one wise use of these stats is buying low on a particular player futures prop that has upside via a lagging statistical indicator (e.g. A batter's batting average rising due to a high barrel rate that hasn't yet manifested).
Park factors — How Stadiums affect runs and home runs
Sites like Baseball Savant (Statcast), Fangraphs, and even mainstream sports sites like ESPN calculate how a baseball stadium can impact batted balls and other offensive and defensive conditions.
While not themselves a one-stop shop for betting picks, park factors with targeted circumstances (wind blowing out in a high-homer PF stadium) could indicate betting opportunities if positive EV (expected value) reveals itself from calculations.
Pythagorean W-L (win-loss)
While sportsbooks are becoming smarter with their trading projections, sometimes vulnerabilities in MLB futures betting can be found in sabermetrics' statistic, which estimates win-loss records based on runs scored and runs allowed.
A team may underperform its Pythagorean due to poor bullpen performance (see Yankees, 2025) and may overperform due to lucky circumstances like a heavily positive outlier, such as an inflated batting average with runners in scoring position.
This will take some in-the-weeds research beyond the simple Pythagoreans listed on MLB.com and elsewhere, but sometimes angles can surface from this wide-sweeping stats sample.
MORE: How to bet MLB home run props
Bankroll and risk management terms
Unit
A standardized measurement to determine the dollar amount of betting, tied to a percentage of their bankroll.
- Common practice puts a unit at somewhere between 1-5% of your bankroll, to encourage long-term planning and rational distribution of your betting bankroll.
- Unit size varies depending on betting experience and bankroll.
- For instance, let's say your initial betting bankroll is $1000, and your unit size is 1%. The first one-unit bet (1u) you make will be $10. If it's 2%, $20, et al.
- When betting on futures, parlays, and other long-shot entries, bettors commonly bet less than one whole unit, recognizing the high-risk, high-reward elements and goal to maximize a minimal investment.
Read more about how to set betting units.
Bankroll
Your total budget allotment to use for sports betting.
Betting bankroll management remains one of the most important steps in maintaing a healthy, balanced habit of sports gambling.
Flat betting
Betting the same amount on every wager ticket you enter.
This is a common positive step toward bankroll management and responsible gambling, instilling consistency, reliability, and accountability in betting.
ROI (return on investment)
A formula measurement of the efficiency and profitability of your bets over your long-term plan.
The formula to calculate return on investment is:
- ROI = (Net Profit / Total Amount Wagered) x 100%
For example, if you bet $1,000 and wound up with a profit of $50, here's the calculation of your ROI:
- ($50 / $1000) x 100% = 5% ROI.
Betting experts generally agree that an ROI of 3-7% is a desirable benchmark in order to most effectively conquer the vig installed by sportsbook. An ROI of 10% generally is reserved for sharps.
MORE: What to know about betting on MLB futures
Common slang and informal betting terms
Chalk
The heavily favored side of a bet or prediction.
Dog
Shorthand for underdog, or the side of a bet with a lower probability of winning.
Bad Beat
Losing a bet in the last few moments of a game or event, or by some extenuating circumstance like an injury, coaching decision, or outside force including weather conditions.
Lock — “Sure Thing” (Spoiler: It’s Not)
A bet that a tout or any bettor says "can't lose."
Caution: There is no such thing as a lock. It's careless marketing that ignores the palpable risks involved in sports betting.
If someone uses this language, go somewhere else for your betting needs.
Public Money
The total amount wagered by casual, inexperienced bettors wager on an event or market, generally leaning toward heavy action on favorites.
Generally, "sharp" bettors work in contradiction to public money, in either direction toward favorites or underdogs.
Public money is typically higher for total tickets on a bet received by the operator, though sharp bettors stock the handle with a much higher total cash amount.
MORE: Full guide to betting on MLB strikeout props
Popular sportsbooks that may be available in your area
Even if sports betting is legal in your state, not all sportsbooks may be available to you. Here are some of the most popular options to look into:
MORE: How sportsbooks set betting lines