Diamondbacks vs Giants Prediction, Odds, Moneyline, Spread & Over/Under for May 20

Odds updated as of 12:11 a.m.

In MLB action on Wednesday, the Arizona Diamondbacks take on the San Francisco Giants.

Here's what you need to know before checking out today's MLB odds and spreads on FanDuel Sportsbook.

Diamondbacks vs Giants Game Info

• Arizona Diamondbacks (23-23) vs. San Francisco Giants (20-28)
• Date: Wednesday, May 20, 2026
• Time: 3:40 p.m. ET
• Venue: Chase Field -- Phoenix, Arizona
• Coverage: Dbacks.TV and NBCS-BA

Diamondbacks vs Giants Odds & Moneyline

• All MLB odds, betting lines and prop bets are available on FanDuel Sportsbook.
• Moneyline: ARI: (-124) | SF: (+106)
• Spread: ARI: -1.5 (+160) | SF: +1.5 (-194)
• Total: 8.5 -- Over: (-110) | Under: (-110)

Diamondbacks vs Giants Probable Starting Pitchers

Probable Pitchers: Merrill Kelly (Diamondbacks) - 3-3, 5.91 ERA vs Tyler Mahle (Giants) - 1-5, 5.59 ERA

The Diamondbacks will give the nod to Merrill Kelly (3-3) against the Giants and Tyler Mahle (1-5). Kelly's team is 3-3-0 against the spread this season in his starts. Kelly's team is 1-1 this season when he starts and they're favored on the moneyline. The Giants are 3-6-0 against the spread when Mahle starts. The Giants have a 2-5 record in Mahle's seven starts this season when they were the underdog on the moneyline.

Diamondbacks vs Giants Prediction & Pick

All MLB win probability predictions and picks are according to numberFire.
Prediction: Diamondbacks win (53.3%)

Diamondbacks vs Giants Moneyline

• Arizona is a -124 favorite on the moneyline, while San Francisco is a +106 underdog on the road.

Diamondbacks vs Giants Spread

• The Diamondbacks are hosting the Giants and are favored by 1.5 runs on the spread. The Diamondbacks are +160 to cover the runline, with the Giants being -194.

Diamondbacks vs Giants Over/Under

• An over/under of 8.5 has been set for Diamondbacks-Giants on May 20, with the over being -110 and the under -110.

Bet on Arizona Diamondbacks vs. San Francisco Giants on FanDuel today!

Diamondbacks vs Giants Betting Trends

• The Diamondbacks have come away with 10 wins in the 16 contests they have been listed as the favorites in this season.
• Arizona has a record of 5-3 when favored by -124 or more this year.
• Contests with the Diamondbacks have gone over the total set by oddsmakers in 23 of 45 chances this season.
• In 45 games with a line this season, the Diamondbacks have a mark of 27-18-0 against the spread.
• The Giants have won 13 of the 34 games they were the underdog on the moneyline this season (38.2%).
• San Francisco is 10-13 (winning 43.5% of its games) when playing as a moneyline underdog of +106 or longer.
• The Giants have played in 48 games with an over/under set, and have combined with opponents to go over the total 21 times (21-24-3).
• The Giants have gone 20-28-0 ATS this season.

Diamondbacks Player Leaders

• Ildemaro Vargas leads Arizona with a slugging percentage of .544, fueled by 17 extra-base hits. He has a .335 batting average and an on-base percentage of .356.
• He is second in batting average, 51st in on-base percentage, and 13th in slugging among all qualifying hitters in MLB.
• Vargas will look for his third straight game with a hit in this contest. In his last five games he is hitting .333 with a double and five RBIs.
• Corbin Carroll leads the Diamondbacks in OBP (.392) and total hits (44) this season. He's batting .284 while slugging .555.
• He ranks 34th in batting average, 13th in on-base percentage and 11th in slugging among qualifying hitters.
• Carroll has picked up at least one hit in seven games in a row. In his last 10 outings he is hitting .353 with four doubles, a triple, two home runs, nine walks and four RBIs.
• Nolan Arenado has collected 40 base hits, an OBP of .347 and a slugging percentage of .463 this season.
• Arenado brings a two-game hitting streak into this game. During his last five outings he is batting .313 with three doubles, a home run, five walks and seven RBIs.
• Geraldo Perdomo has been key for Arizona with 34 hits, an OBP of .344 plus a slugging percentage of .353.
• Perdomo has hit safely in four straight games. In his last five games he is hitting .250 with a double and five walks.

Giants Player Leaders

• Luis Arraez has a .365 on-base percentage and a .432 slugging percentage, both team-best numbers for the Giants. He's batting .324.
• Including all the qualified hitters in the big leagues, his batting average is fifth, his on-base percentage ranks 38th, and he is 64th in slugging.
• Casey Schmitt leads his team with 44 hits. He has a batting average of .295 while slugging .523 with an on-base percentage of .342.
• He is currently 21st in batting average, 70th in on-base percentage and 19th in slugging percentage among all qualifying hitters.
• Jung Hoo Lee is batting .268 with 10 doubles, a triple, three home runs and 10 walks.
• Rafael Devers is batting .240 with 10 doubles, five home runs and 13 walks.

Diamondbacks vs Giants Head to Head

• 5/18/2026: 12-2 ARI (Favorite: Diamondbacks, Spread: -1.5, Total: 9, Favorite Moneyline: -136, Underdog Moneyline: +116)
• 9/17/2025: 5-1 SF (Favorite: Diamondbacks, Spread: -1.5, Total: 9, Favorite Moneyline: -108, Underdog Moneyline: -108)
• 9/16/2025: 6-5 ARI (Favorite: Diamondbacks, Spread: -1.5, Total: 9, Favorite Moneyline: -130, Underdog Moneyline: +110)
• 9/15/2025: 8-1 ARI (Favorite: Diamondbacks, Spread: -1.5, Total: 9, Favorite Moneyline: -132, Underdog Moneyline: +112)
• 9/10/2025: 5-3 ARI (Favorite: Giants, Spread: -1.5, Total: 8.5, Favorite Moneyline: -126, Underdog Moneyline: +108)
• 9/9/2025: 5-3 SF (Favorite: Giants, Spread: -1.5, Total: 7.5, Favorite Moneyline: -142, Underdog Moneyline: +120)
• 9/8/2025: 11-5 SF (Favorite: Giants, Spread: -1.5, Total: 7.5, Favorite Moneyline: -174, Underdog Moneyline: +146)
• 7/3/2025: 7-2 SF (Favorite: Giants, Spread: -1.5, Total: 8.5, Favorite Moneyline: -126, Underdog Moneyline: +108)
• 7/2/2025: 6-5 SF (Favorite: Diamondbacks, Spread: -1.5, Total: 8.5, Favorite Moneyline: -146, Underdog Moneyline: +124)
• 7/1/2025: 8-2 ARI (Favorite: Diamondbacks, Spread: -1.5, Total: 9, Favorite Moneyline: -130, Underdog Moneyline: +110)

Sign up for FanDuel Sportsbook and FanDuel Daily Fantasy today!