Subaru Outback 12V battery size and replacement
The short answer
For a North American 2011 Subaru Outback, parts catalogs commonly list a Group 35 12-volt battery for both the 2.5i (four-cylinder) and 3.6R (six-cylinder) versions. "Group" is a battery industry size code. It defines the case dimensions and the position and type of the terminals, so a battery with the right group number should fit the tray, the hold-down and the cable reach.
Treat that as a starting point, not a final answer. This article does not draw on a manufacturer specification sheet, so confirm the size using one of the checks below before you buy. The checks matter most if your car was sold outside North America or if the battery has been replaced before.
Conditions that can change the answer
Market: Outbacks sold in Japan, Europe, Australia and other regions may use batteries labeled under different sizing systems, such as Japanese JIS or European DIN/EN codes, and may not use Group 35. Powertrain: Engine options differed by market, including a diesel in some regions. A diesel or a different engine can call for a different battery size or a higher rating than the North American gasoline models. Previous replacements: A previous owner or shop may have fitted a different group size. Copying the label on the battery that is in the car now could repeat an earlier mistake. Climate and equipment: Two batteries in the same group can have different ratings. If you live somewhere very cold or have added electrical accessories, the rating matters as much as the physical size.
Ratings to compare once the size is confirmed
Cold cranking amps (CCA) measures how much current a battery can deliver to start the engine in freezing conditions. As a general rule, choose a replacement with a CCA rating at least equal to the original equipment specification. Exact CCA and reserve capacity figures for the 2011 Outback have not been verified for this article, so take them from your owner's manual or the original battery label rather than from a general guide.
Reserve capacity indicates how long a battery can power the car's electrical systems if the charging system stops working. It is worth comparing when two batteries of the same group size and similar CCA are priced differently.
How to confirm the right battery
Check the owner's manual. The specifications section usually lists the battery type or rating for your market. Read the label on the current battery. Note the group or size code and the CCA. Then confirm that this battery fits properly and that the cables reach the terminals without strain. Give a parts counter or online catalog the full vehicle details: model year, market, trim and engine. A lookup by VIN is the most reliable option where it is offered. Compare terminal positions. Positive and negative posts must be on the same sides as on the original battery, or the cables may not reach.
Replacement points that affect fit
A battery that is the wrong group size may sit loosely under the hold-down clamp or may not fit in the tray at all. A loose battery can shift while driving and damage the terminals or the case, so the correct physical size matters even when a different battery would technically start the car.
Disconnecting the battery can reset stored settings such as radio presets and the clock. Your owner's manual is the reference for any reset or relearn steps that apply to your model.