Group 27 battery size

Close in size

No other group in the BCI table comes within 10 mm (0.4 in) of group 27 on all three sides: look for group 27 itself.

Before you buy a group 27 battery

• Read the group number on the label of the battery in your car, or in the owner's manual: it should say 27.
• A group with an "R" after the number has its terminals reversed: do not swap one for the other without checking where your cables reach.
• Choose cold cranking amps (CCA) at least as high as the original, especially for cold winters.
• Measure your battery tray and the room above it, then compare with the size printed for the exact battery you pick, not only with the group number.
• Group 27 has top posts: the new battery must match, and the hold-down must fit the box.
• Most stores take the old battery back for recycling, often against a core charge.

Good to know about group 27

• Group 27 has the same width and height as group 24 but is longer, so it needs a longer tray.^1,2,3
• Most retailers' specifications list the positive terminal of a group 27 on the left and of a 27F on the right, but not every listing agrees: check your old battery before you buy.^3,4,5,6,7
• Group 27 is common in boats and RVs, including RV house batteries and trolling-motor power.^8,9,10
• Group 27 is sold in deep-cycle, dual-purpose and AGM versions.^7,9,10,11,12
• Marine group 27 batteries (27M) commonly have threaded studs as well as posts.^11,12

How we checked this page

Checked on October 16, 2026. We kept a fact only when two independent sources agree, and each one is numbered to its sources below. We never write a price: the listings come straight from eBay and show what sellers ask. This page was written with an AI assistant and checked against the sources below.

Sources

1. BCI group numbers, dimensional specifications and ratings, Battery Council International
2. Duracell Ultra car battery, group 24 (SLI24), Batteries Plus
3. Duracell Ultra car battery, group 27 (SLI27), Batteries Plus
4. NAPA battery BCI No. 27 (BAT 7527), NAPA Auto Parts
5. Group 27F AGM battery (SLI27FAGM), Batteries Plus
6. NAPA battery BCI No. 27F (BAT 7527F), NAPA Auto Parts
7. NAPA Commercial AGM battery BCI No. 27, NAPA Auto Parts
8. Group 27 batteries, Battery Mart
9. Interstate Batteries marine battery, group size 27, Pep Boys
10. Optima BlueTop 27M, Batteries Plus
11. Optima BlueTop dual purpose marine battery, group 27 (D27M), Defender
12. Duracell Ultra marine and RV battery, group 27M (SLI27MDP), Batteries Plus