Car battery group sizes
A car battery's group size is a Battery Council International (BCI) code for its case dimensions, terminal position and type.[1 · Oct 29, 2026] All group 24 batteries, for example, share similar case dimensions and terminal layout.[2 · Oct 29, 2026]
What the group size covers
- Dimensions: length, width and height, within 2 mm.[1 · Oct 29, 2026]
- Performance: cold cranking amps (CCA) and amp-hours.[1 · Oct 29, 2026]
- Terminal position and chemistry: flooded is the default; EFB and AGM have their own designations, and there are lithium iron phosphate (LFP) groups too.[1 · Oct 29, 2026]
- BCI groups line up with DIN, EN and JIS sizes, and retailers look up vehicles in BCI's database of more than 160,000 vehicles.[1 · Oct 29, 2026]
Common BCI groups
| Group (DIN) | Max L × W × H, mm | Inches (approx.) | O.E. CCA range |
|---|---|---|---|
| 24 | 260 × 173 × 225 | 10.2 × 6.8 × 8.9 | 200–1000 |
| 24F | 273 × 173 × 229 | 10.7 × 6.8 × 9.0 | 250–900 |
| 25 | 230 × 175 × 225 | 9.1 × 6.9 × 8.9 | 260–660 |
| 34 | 260 × 173 × 200 | 10.2 × 6.8 × 7.9 | 235–1000 |
| 35 | 230 × 175 × 225 | 9.1 × 6.9 × 8.9 | 300–640 |
| 47 (H5) | 242 × 175 × 190 | 9.5 × 6.9 × 7.5 | 290–680 |
| 48 (H6) | 278 × 175 × 190 | 10.9 × 6.9 × 7.5 | 315–850 |
| 49 (H8) | 353 × 175 × 190 | 13.9 × 6.9 × 7.5 | 470–950 |
| 51R | 238 × 129 × 223 | 9.4 × 5.1 × 8.8 | 295–500 |
| 65 | 306 × 192 × 192 | 12.0 × 7.6 × 7.6 | 540–880 |
| 75 | 230 × 180 × 186 | 9.1 × 7.1 × 7.3 | 425–690 |
| 78 | 260 × 180 × 186 | 10.2 × 7.1 × 7.3 | 465–875 |
| 86 | 230 × 173 × 203 | 9.1 × 6.8 × 8.0 | 430–640 |
| 94R (H7) | 315 × 175 × 190 | 12.4 × 6.9 × 7.5 | 440–900 |
| 96R | 242 × 175 × 175 | 9.5 × 6.9 × 6.9 | 400–590 |
| 121R | 208 × 177 × 215 | 8.2 × 7.0 × 8.5 | 410–600 |
| 124R | 262 × 177 × 218 | 10.3 × 7.0 × 8.6 | 500–740 |
| 140R (H4) | 207 × 175 × 190 | 8.1 × 6.9 × 7.5 | 285–570 |
| 151R | 188 × 125 × 225 | 7.4 × 4.9 × 8.9 | 340–370 |
Maximum overall dimensions and original-equipment CCA ranges from BCI's group size chart, which says the designs and designations are for reference only and to check with your battery supplier for dimensional details.[3 · Oct 29, 2026] "R" groups have reversed terminals; BCI notes that a 148 is a 48 (H6) with reversed terminals.[3 · Oct 29, 2026]
Which group does my car take?
We don't list vehicle fitments. Check the label on the battery you have now, or your owner's manual. Retailers look up fitment from BCI's vehicle database.[1 · Oct 29, 2026] Match the group size and terminal layout, then meet or beat the CCA your vehicle maker specifies.
The numbers on the label
| CCA (cold cranking amps) | Amps a 12 V battery delivers for 30 seconds at 0°F (−17.8°C) while staying at or above 7.2 V.[2 · Oct 29, 2026] |
|---|---|
| CA (cranking amps) | The same test at 32°F (0°C); not the same number as CCA.[2 · Oct 29, 2026] |
| RC (reserve capacity) | Minutes a fully charged new battery at 80°F can deliver 25 A and stay at or above 10.5 V, to run essentials if the charging system fails.[2 · Oct 29, 2026] |
| AGM | Absorbent glass mat: the electrolyte is held in glass mats, so it won't spill and needs no water.[2 · Oct 29, 2026] |
| Fully charged | A 12 V battery reads 12.66 V or more.[2 · Oct 29, 2026] |
Old car batteries
Don't put a lead-acid car battery in the trash. The EPA says to return it to a battery retailer or a household hazardous waste collection site; one can hold up to 18 pounds of lead.[4 · Oct 29, 2026]
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Sources: 1. Battery Council International, BCI group sizes. 2. Interstate Batteries, Battery glossary. 3. Battery Council International, BCI group numbers, dimensional specifications and ratings (PDF). 4. US EPA, Used household batteries. Checked Oct 29, 2026. Inch conversions are our own arithmetic from the millimeter figures. Brand names and trademarks belong to their owners; specs are restated in our own words and tables, not reproduced.