The Mazda 3 OEM battery’s group size number could vary depending on its model year, engine type, or other factors—possible group sizes for a Mazda 3 OEM battery could include 35, H5, and 26R.
There are a few places you can look to find out your Mazda 3 OEM battery’s group number, including your owner’s manual and the information on the battery itself. Auto parts stores also usually have tools that let you check whether a particular car battery is compatible with your vehicle.