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Detached Garage EV Charger Cost Calculator

When the panel is in the house and the car is in a detached garage, most of the cost is in getting power across the yard. Estimate the trench, conduit, wire size for the distance and an optional garage subpanel.

Charger
A subpanel lets the garage also have lights, outlets or a second charger.
Route
ft
ft
ft
Costs

Results

Estimated project cost$1,650 – $3,540Midpoint $2,590
Circuit50 A · 8 AWG Cu
Voltage drop at charger load2.3%
Trenching share20%
Estimated project components
ComponentEstimated range
Level 2 charger (40 A)$450 – $750
Electrician labor, breaker & terminations (both ends)$450 – $1,000
Wire: 90 ft of 8 AWG copper THHN$200 – $320
Trench 60 ft (machine-trenched)$300 – $720
Conduit & fittings, 90 ft$180 – $450
Permit & inspection$80 – $300

Trench depth depends on the wiring method: NEC Table 300.5 commonly requires about 18 in. of cover for PVC conduit and 24 in. for direct-burial cable, with exceptions and local amendments. Call 811 before digging.

A detached building fed by more than one circuit needs its own disconnect and grounding electrode system. A single EV circuit usually avoids a subpanel, but garage lighting and outlets would need another circuit or a subpanel.

Based on the entered information, a load review or panel upgrade may be required — this estimate does not include service upgrades. Final sizing should be confirmed by a licensed electrician.

Ranges are typical U.S. pricing used as planning assumptions, not a quote.

How it works

  1. Choose the charger output and whether the garage gets only an EV circuit or a subpanel feeder.
  2. Enter the total wire length from the panel to the charger and how much of it runs underground.
  3. Enter any length that crosses concrete or asphalt and choose how the trench will be dug.
  4. Read the cost range, the wire size chosen for the distance and the breakdown of project components.

Formula

Circuit = 125% × charger current (or the subpanel feeder size)
Wire = smallest gauge with ampacity ≥ circuit and voltage drop ≤ 3% over the run
Cost = charger + labor + wire × length + trench × $/ft + hardscape × $/ft + conduit + subpanel + permit

Assumptions (typical U.S. pricing, planning only): trenching $5–$12/ft by machine, $8–$15/ft by hand, $15–$35/ft by directional bore; concrete or asphalt crossings $20–$50/ft; conduit and fittings $2–$5/ft; detached-building labor $450–$1,000; subpanel installed $400–$900 (60 A) or $600–$1,400 (100 A). Wire prices per foot by gauge, copper for an EV circuit and aluminum for a feeder. Voltage drop uses NEC Chapter 9 resistance at the charger current and 240 V.

Example

A 48 A charger in a detached garage 140 ft of wire from the house panel, with 100 ft underground including 12 ft under the driveway, fed by a 100 A subpanel so the garage can also have lights and outlets.

Inputs

Charger output
48 A (11.5 kW)
I already have the charger
No
Power to the garage
100 A subpanel feeder (aluminum)
Total wire run, panel to charger
140 ft
Length underground
100 ft
Of which under concrete / asphalt
12 ft
Trench method
Machine trencher
Include permit & inspection
Yes
Area cost level
Average

Result

Estimated project cost$3,000 – $6,490Midpoint $4,740
Feeder100 A · 1 AWG Al
Voltage drop at charger load1.4%
Trenching share25%
Load this example into the calculator →

Single circuit or subpanel?

If the garage only needs the charger, one dedicated circuit is the simplest option. If you also want lights, outlets, a workshop or a second charger later, a feeder to a small subpanel costs more up front but avoids digging twice. A detached building supplied by more than one circuit needs a disconnect and its own grounding electrodes.

Long runs raise the wire size. Aluminum feeder cable is much cheaper per foot than copper at the larger sizes, which is why subpanel feeders are commonly aluminum.

Planning estimate, not a design

Burial depth, conduit type, conductor sizing and grounding for detached buildings are set by the electrical code adopted where you live and by the inspector. Your service capacity decides whether the house panel can supply the new load — based on the entered information, a load review or panel upgrade may be required. Final sizing should be confirmed by a licensed electrician.

Frequently asked questions

How much does it cost to run power to a detached garage for an EV charger?

For 50–100 ft with a machine-dug trench, projects commonly land around $1,700–$4,500 including the charger; driveway crossings, boring or a subpanel push it higher.

How deep does the trench need to be?

Under NEC Table 300.5, PVC conduit commonly needs about 18 in. of cover and direct-burial cable about 24 in., with exceptions under driveways and in some locations. Your local inspector has the final say.

Do I need a subpanel in a detached garage?

Not for a single EV circuit. You need one if the garage will have several circuits, because a detached building may be supplied by only one feeder or branch circuit in most cases.

Do I need to upgrade my main panel to 200 A?

Not automatically. A load calculation decides whether the existing service can carry the charger; a lower charger setting or load management can sometimes avoid an upgrade. A licensed electrician should make that call.