Mariners vs Royals Prediction, Odds, Moneyline, Spread & Over/Under for May 3

Odds updated as of 11:14 p.m.

The Seattle Mariners are among the MLB teams in action on Sunday, up against the Kansas City Royals.

We've got you covered, in terms of the most important information about this matchup before you take a look at the MLB odds and spreads on FanDuel Sportsbook.

Mariners vs Royals Game Info

• Seattle Mariners (16-17) vs. Kansas City Royals (13-19)
• Date: Sunday, May 3, 2026
• Time: 4:10 p.m. ET
• Venue: T-Mobile Park -- Seattle, Washington
• Coverage: Mariners.TV and Royals.TV

Mariners vs Royals Odds & Moneyline

• All MLB odds, betting lines and prop bets are available on FanDuel Sportsbook.
• Moneyline: SEA: (-142) | KC: (+120)
• Spread: SEA: -1.5 (+146) | KC: +1.5 (-178)
• Total: 8 -- Over: (-108) | Under: (-112)

Mariners vs Royals Probable Starting Pitchers

Probable Pitchers: Luis Castillo (Mariners) - 0-2, 6.35 ERA vs Kris Bubic (Royals) - 2-1, 3.74 ERA

The Mariners will give the ball to Luis Castillo (0-2, 6.35 ERA), who is eyeing win No. 1 on the season, and the Royals will turn to Kris Bubic (2-1, 3.74 ERA). Castillo's team is 1-5-0 against the spread this season in his starts. Castillo's team has a record of 1-4 this season when he starts and they are the favorite on the moneyline. The Royals are 3-3-0 ATS in Bubic's six starts with a set spread. The Royals have always been the moneyline underdog when Bubic starts this season.

Mariners vs Royals Prediction & Pick

All MLB win probability predictions and picks are according to numberFire.
Prediction: Mariners win (54.9%)

Mariners vs Royals Moneyline

• Seattle is the favorite, -142 on the moneyline, while Kansas City is a +120 underdog on the road.

Mariners vs Royals Spread

• The Royals are +1.5 on the spread (-178 to cover), and Seattle is +146 to cover the runline.

Mariners vs Royals Over/Under

• A total of 8 runs has been set for the Mariners-Royals contest on May 3, with the over available at -108 and the under at -112.

Bet on Seattle Mariners vs. Kansas City Royals on FanDuel today!

Mariners vs Royals Betting Trends

• The Mariners have won in 15, or 51.7%, of the 29 contests they have been named as odds-on favorites in this year.
• Seattle has a record of 9-7 in contests when sportsbooks favor them by -142 or more on the moneyline.
• Contests with the Mariners have gone over the total set by oddsmakers in 16 of 33 chances this season.
• The Mariners have posted a record of 12-21-0 against the spread this season.
• The Royals have gone 4-11 in games they were listed as the moneyline underdog (winning 26.7% of those games).
• When playing as a moneyline underdog with odds of +120 or longer, Kansas City has gone 2-3 (40%).
• The Royals have combined with opponents to go over the total 13 times this season for a 13-17-0 record against the over/under.
• The Royals have collected a 13-17-0 record against the spread this season (covering 43.3% of the time).

Mariners Player Leaders

• Randy Arozarena leads Seattle in OBP (.377), slugging percentage (.458) and total hits (34) this season. He has a .288 batting average.
• Among qualifying hitters in MLB, he is 40th in batting average, 34th in on-base percentage, and 55th in slugging.
• Cole Young has four doubles, a triple, three home runs and 11 walks. He's batting .276 and slugging .405 with an on-base percentage of .346.
• Among qualified hitters, his batting average places him 48th, his on-base percentage 71st, and his slugging percentage 92nd.
• Julio Rodriguez has hit four homers with a team-high .400 SLG this season.
• Rodriguez enters this game with three games in a row with at least one hit. In his last five games he is batting .318 with three doubles, two home runs and six RBIs.
• Josh Naylor has been key for Seattle with 25 hits, an OBP of .285 plus a slugging percentage of .333.

Royals Player Leaders

• Bobby Witt Jr. has racked up a team-high OBP (.368) and slugging percentage (.424). He's batting .288.
• Including all qualified hitters in MLB, his batting average puts him 40th, his on-base percentage ranks 47th, and he is 76th in slugging.
• Maikel Garcia has eight doubles, a triple, three home runs and 13 walks while hitting .274. He's slugging .436 with an on-base percentage of .344.
• His batting average is 52nd among all qualified players, his on-base percentage is 72nd, and he is 67th in slugging.
• Vinnie Pasquantino has three doubles, two triples, four home runs and 16 walks while batting .176.
• Carter Jensen leads his team with 23 hits.

Mariners vs Royals Head to Head

• 5/1/2026: 7-6 KC (Favorite: Mariners, Spread: -1.5, Total: 7, Favorite Moneyline: -148, Underdog Moneyline: +126)
• 9/18/2025: 2-0 SEA (Favorite: Mariners, Spread: -1.5, Total: 9, Favorite Moneyline: -120, Underdog Moneyline: +102)
• 9/17/2025: 7-5 KC (Favorite: Royals, Spread: -1.5, Total: 8.5, Favorite Moneyline: -124, Underdog Moneyline: +106)
• 9/16/2025: 12-5 SEA (Favorite: Mariners, Spread: -1.5, Total: 8.5, Favorite Moneyline: -136, Underdog Moneyline: +116)
• 7/3/2025: 3-2 KC (Favorite: Mariners, Spread: -1.5, Total: 7.5, Favorite Moneyline: -120, Underdog Moneyline: +102)
• 7/2/2025: 3-2 SEA (Favorite: Mariners, Spread: -1.5, Total: 7, Favorite Moneyline: -166, Underdog Moneyline: +140)
• 7/1/2025: 6-3 KC (Favorite: Mariners, Spread: -1.5, Total: 8, Favorite Moneyline: -138, Underdog Moneyline: +118)
• 6/30/2025: 6-2 SEA (Favorite: Mariners, Spread: -1.5, Total: 7, Favorite Moneyline: -164, Underdog Moneyline: +138)
• 6/9/2024: 6-5 SEA (Favorite: Royals, Spread: -1.5, Total: 7.5, Favorite Moneyline: -136, Underdog Moneyline: +116)
• 6/8/2024: 8-4 KC (Favorite: Mariners, Spread: -1.5, Total: 8.5, Favorite Moneyline: -134, Underdog Moneyline: +114)

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