What does a subpanel cost for a garage, ADU or addition?

Basis: estimate. The $1,200 to $2,800 range is a desk estimate for a typical SoCal job as of October 2026. There is no published SoCal subpanel price list. Two points help bracket it. A national cost site lists subpanel materials at only $100 to $400, which is a floor, not an installed price. Fixr’s national guide also says the full cost of a subpanel is similar to a standard panel installation, which it prices at $1,200 to $1,800 for 100 amps and $1,800 to $4,500 for 200 amps, labor included.

How a subpanel is sized and wired is on the subpanel installation page.

What you are paying for

The panel itself is cheap. The cost is the feeder, the labor and the inspection. A typical job includes:

• A subpanel sized for the loads
• A feeder from the main panel (wire, conduit, a breaker)
• Grounding and bonding that follow code for a separate building
• A first set of breakers
• The permit and inspection

The distance question

A subpanel inside the house, ten feet from the main panel, is a small job. A subpanel in a detached garage or ADU is a different job, because the feeder must go underground or overhead across the yard. The trenching, conduit and wire can cost more than the panel. Ask each bidder for the feeder length they assumed.

When the main panel is the problem

A subpanel adds capacity on paper, but the main panel and the service still have to carry the load. If the main panel is full or small, the electrician may suggest a panel upgrade first. That is why the two jobs are often bundled. A load calculation shows whether the existing service can feed a new subpanel. See the ADU electrical guide for how that works with a second dwelling.

Special cases

• Backup power. A subpanel for critical loads is its own job. See critical-loads subpanels.
• EV charging in a detached garage. The feeder work often decides the cost. Compare against the EV charger cost page.
• Remodels and ADUs. Plan the subpanel size for future loads so you do not rewire later. See ADU and remodel electrical.

Putting the sources side by side

Source	What it covers	Figure
National cost site	Subpanel materials only	$100 to $400
Fixr, national	Full panel installation, 100 amps (a subpanel costs about the same)	$1,200 to $1,800
Fixr, national	Full panel installation, 200 amps (a subpanel costs about the same)	$1,800 to $4,500

The range on this page, $1,200 to $2,800, is a desk estimate that starts at the 100-amp installed figure. Materials are a small slice, so most of the spread comes from feeder length and trenching, not from the panel.

Permits, and when the utility is involved

A subpanel is a permitted job. The fee depends on your city, and an ADU adds its own review. Use the city pages or the county hubs, such as Orange County and San Bernardino County. A subpanel on the customer side of the meter usually does not need utility work unless the main service changes.

How to compare quotes

1. Ask for the subpanel size in amps and the number of spaces.
2. Ask for the feeder length, wire size and conduit type.
3. Ask whether trenching and concrete cutting are included.
4. Ask whether the price assumes the main panel has room.
5. Ask what the permit fee is and who pays it.

What is not included

Trenching by a separate contractor, concrete or landscaping repair, drywall patching, a main panel upgrade, and the circuits you add later. The range above is for a normal single-family lot.