Does Car Battery Size Matter? 

A car battery is designed to deliver a short but powerful burst of energy to start the engine. It’s also used as a power source for electronics, safety systems, and accessories when the engine isn’t running. In every vehicle, including EVs, a 12-volt battery is installed into a designated space and connected with thick, durable cables, and the battery’s size might be more important than you think.

If you’re replacing the battery in your car, prices can range from around $75 to more than $400. However, only a few of the listed options may work for your vehicle. Here’s what you need to know about battery size and how to choose the right one.

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Does car battery size matter for my car? 

If you’re installing batteries into a remote control, a drone, or some other battery-powered device, it will only operate if the correct batteries are used. AA batteries won’t fit into a space for AAA batteries, for example, and a 9-volt battery won’t work in the place of a CR2032 battery.  

While all car batteries operate on 12 volts, vehicles have different electrical demands, available space for a battery, and terminal configuration requirements. The manufacturer equips a vehicle from the factory with a battery that’s suited for its needs, and the same replacement size, orientation, and capacity should be used.  

Battery sizes are grouped together based on similar criteria including the physical dimensions, the types of terminals, and the overall configuration. While amp-hours (AH) isn’t part of the grouping, there tends to be a correlation due to the dimensions.  

Battery Council International, or BCI, has introduced Group Sizes for similarly sized batteries. It makes it much easier to shop for a replacement battery since you only need to make sure the BCI Group Size is the same as the one installed from the factory, and it has the same or higher amp-hours as the old one. Every Group Size 35 battery, for instance, will have the same dimensions and terminal configuration. 

What happens if you put the wrong size battery in your car? 

woman removing a battery from her engine compartment to demonstrate how car batteries work
What happens if you put the wrong size battery in your car?

If you’ve chosen the wrong battery size, either intentionally or accidentally, fitment can be an issue for your car.  

  • Poor physical fit. Choosing a battery that has a larger width or length may mean it doesn’t fit into the battery tray and can’t be secured safely.  
  • Contact with the hood. If the battery is too tall, the battery hold-down may not fit to secure it or the terminals could contact the hood and arc. 
  • The battery cables might not reach. If the BCI Group Size you choose has a terminal orientation opposite to your required battery size, the negative and positive cables may not reach the posts. 
  • Wrong terminal design. Your car might need side posts and won’t work with a top-post battery, or vice versa. 
  • Damage to electronics. If you connect a battery with reversed polarity, it can damage onboard computers, fry wiring, or cause other serious and expensive electrical issues. 
  • Insufficient cranking amperage. Selecting a battery that’s too small for your car can impact cold cranking as there isn’t enough stored energy to turn over the engine in cold weather. 
  • Shortened battery life. If the battery does fit, the wrong size may not have the ability to recharge properly from your alternator. It can lead to sulfation that shortens its useful life.  

Does car battery size matter? Yes, it does! While there might be a few compatible batteries, like a Group Size 26R and 35, there are very few matches that have the same physical dimensions and amp-hours that will work for your vehicle. 

How to know what car battery size to buy?  

To select the correct size, determine the BCI Group Size that your vehicle was equipped with from the factory. You’ll find this number in a few locations:  

  • On the battery label 
  • In your vehicle’s service information 
  • On a BCI Group Size chart 

Here’s a battery sizes chart with dimensions for many of the popular BCI Group Sizes.


GroupMillimeters  Inches  
212081732228  3/166 13/168 3/4
22F2411752119 1/26 7/88  5/16
22HF2411752299 1/26 7/89
22NF2401402279  7/165 1/28 15/16
22R22917521196 7/88  5/16
2426017322510 1/46 13/168 7/8
24F27317322910 3/46 13/169
24H26017323810 1/46 13/169 3/8
24R26017322910 1/46 13/169
24T26017324810 1/46 13/169 3/4
252301752259  1/166 7/88 7/8
262081731978  3/166 13/167 3/4
26R2081731978  3/166 13/167 3/4
2730617322512  1/166 13/168 7/8
27F31817322712 1/26 13/168 15/16
27H29817323511 3/46 13/169 1/4
29NF330140227135 1/28 15/16
3333817323813  5/166 13/169 3/8
3426017320010 1/46 13/167 7/8
34R26017320010 1/46 13/167 7/8
352301752259  1/166 7/88 7/8
36R26318320610 3/87 1/48 1/8
40R27717517510 15/166 7/86 7/8
4129317517511  3/166 7/86 7/8
422431731739  5/166 13/166 13/16
4333417520513 1/86 7/88  1/16
452401402279  7/165 1/28 15/16
4627317322910 3/46 13/169
472461751909 11/166 7/87 1/2
4830617519212  1/166 7/87  9/16
49381175192156 7/87  3/16
5034312725413 1/2510
512381292239 3/85  1/168 13/16
51R2381292239 3/85  1/168 13/16
521861472107  5/165 13/168 1/4
53330119210134 11/168 1/4
541861542127  5/166  1/168 3/8
552181542128 5/86  1/168 3/8
56254154212106  1/168 3/8
572051831778  1/167  3/166 15/16
5825518317710  1/167  3/166 15/16
58R25518317710  1/167  3/166 15/16
5925519319610  1/167 5/87 3/4
6033216022513  1/166  5/168 7/8
611921622257  9/166 3/88 7/8
622251622258 7/86 3/88 7/8
6325816222510  3/166 3/88 7/8
6429616222511 11/166 3/88 7/8
6530619019212  1/167 1/27  9/16
702081791968  3/167  1/167 11/16
712081792168  3/167  1/168 1/2
722301792109  1/167  1/168 1/4
732301792169  1/167  1/168 1/2
7426018422210 1/47 1/48 3/4
752301791969  1/167  1/167 11/16
7633417921613 1/87  1/168 1/2
7826017919610 1/47  1/167 11/16
852301732039  1/166 13/168
862301732039  1/166 13/168
902461751759 11/166 7/86 7/8
91280175175116 7/86 7/8
9231717517512 1/26 7/86 7/8
93354175175156 7/86 7/8
95R39417519015  9/166 7/87 1/2
96R2421731759  9/166 13/166 7/8
97R2521751909 15/166 7/87 1/2
98R28317519011  3/166 7/87 1/2


GroupMillimeters  Inches  
12321812389 1/87 1/89 3/8
226418123810 3/87 1/89 3/8
2E49210523219  7/164 1/89 1/8
2N254141227105  9/168 15/16
17HF1871752297 3/86 7/89


GroupMillimeters  Inches  
4D52722225020 3/48 3/49 7/8
6D52725426020 3/41010 1/4
8D52728325020 3/411 1/89 7/8
2826117324010  5/166 13/169  7/16
29H33417123213 1/86 3/49 1/8 10
30H34317323513 1/26 13/169 1/4 10
31330173240136 13/189  7/16


GroupMillimeters  Inches  
GC226418327010 3/87  3/1610 5/8
GC2H26418329510 3/87  3/1611 5/8

You can also find your BCI car battery size by searching AutoZone’s batteries by year, make, model, and engine size. If you have any questions or concerns about fitment, an AutoZone associate would be happy to help you find excellent options to fit your vehicle. If the job is too big for you, seek out one of our Preferred Shops to help you do the job.

FAQ/People Also Ask 

What happens if you put the wrong size battery in your car?  

The wrong size battery might exhibit no immediate symptoms at all. However, it could arc against the hood if it’s not secured properly, fail prematurely, have insufficient power, or it could cause serious electrical issues. 

Can the wrong battery damage the alternator? 

A weak or dead battery can kill an alternator, but typically, the wrong battery won’t cause damage to the alternator.  

What happens if amps are too high?  

It’s okay to use a battery with higher amp-hours or cold cranking amps than the original battery. This simply means more reserve power is available for your vehicle. 

Can a car battery be too small for a car? 

It’s possible for a battery’s physical dimensions to be too small for a car, meaning it can’t be secured properly under the hood. As well, a battery’s cranking amps can be too low, meaning there’s not enough energy to start the car in cold weather. 

Advice, how-to guides, and car care information featured on and AutoZone Advice & How-To’s are presented as helpful resources for general maintenance and automotive repairs from a general perspective only and should be used at your own risk. Information is accurate and true to the best of AutoZone’s knowledge, however, there may be omissions, errors or mistakes.

Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

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