Why multiply EV charger amps by 1.25?

EVSE loads are typically continuous (3 hours or more). A common NEC 625-style screen sizes the branch-circuit OCPD at 125% of the maximum continuous current so the breaker is not run at 100% continuously.

Is a 40 A breaker OK for a 32 A EV charger?

Yes as a screening result: 32 × 1.25 = 40 A. The conductor must also meet ampacity for that breaker—verify in the Cable Size calculator.

EV Charger Load Calculator

Screen Level 2 EVSE continuous amps and a 125% breaker frame—instant load planning for home charger circuits.

Calculator

Quick: continuous amps × 1.25 → breaker. Advanced: enter kW at voltage instead of amps.

Input mode

EVSE continuous current (A) Use the charger’s continuous / max continuous setting (not a short surge).

Voltage (V)

Continuous factor Default 125% for continuous EVSE branch-circuit screening. Final design follows code, OEM, and AHJ.

About this calculator

Screens EV charger / EVSE continuous load and a breaker frame with a 125% continuous factor. It is not a full NEC 220 dwelling load calculation or OEM installer app. For home Level 2 buying context, open the EV charger for home sizing guide. Continue with cable sizing and the general breaker size calculator on the protection calculators hub.

Calculation Results

Min breaker screen: 40 A

32 A continuous × 1.25 = 40 A → next frame 40 A. This is a planning screen, not a conductor selection or installation approval.

Assumptions: single-phase branch; continuous EVSE; no load management / power sharing modeled. Panel spare capacity must still pass a dwelling load calc.

Continue Your Calculation

Size the EVSE feeder conductor for the screened breaker duty, then check route length in Voltage Drop.

Cable sizing →

Planning disclaimer

Educational screen only—not a substitute for NEC Article 625 / 220 design, manufacturer instructions, or AHJ approval. Hire a licensed electrician. Confirm GFCI/AFCI and disconnect requirements for your jurisdiction.

EV charger breaker size chart (125% screen)

Common Level 2 continuous settings with a 125% arithmetic screen. Open a row to load the calculator. Conductor size is intentionally not inferred from breaker rating alone. Home buying context: EV charger for home sizing.

× 1.25	Breaker screen	≈ kW @ 240 V	Conductor next step
20	20 A	3.8 kW	Verify ampacity and voltage drop
40	40 A	7.7 kW	Verify ampacity and voltage drop
50	50 A	9.6 kW	Verify ampacity and voltage drop
60	60 A	11.5 kW	Verify ampacity and voltage drop

Formula & explanation

Breaker_min ≥ I_continuous × 1.25 (typical continuous EVSE screen)

From kW (1φ): I_continuous = (kW × 1000) ÷ V

80% rule? Running a breaker at ≤80% continuous is the flip side of sizing OCPD at 125% of continuous load—same math, different wording.

Example: 48 A continuous @ 240 V → 48 × 1.25 = 60 A breaker screen · ≈ 11.5 kW.

Chain: this page → cable size → voltage drop · general OCPD ladder: breaker size. Hub: protection calculators.

When to use which protection tool

Goal	Tool
EVSE continuous A → breaker frame	This page
General feeder / motor OCPD ladder	Breaker Size Calculator
AWG / mm² ampacity	Cable Size Calculator
Long garage run voltage drop	Voltage Drop Calculator

Frequently Asked Questions

What size breaker do I need for an EV charger?

Breaker ≥ continuous A × 1.25, then next standard frame. Example: 32 A → 40 A; 48 A → 60 A.

Why multiply by 1.25?

EVSE is typically a continuous load. The 125% screen keeps the OCPD from running at 100% continuous—often called the “80% rule” from the other direction.

Is a 40 A breaker OK for a 32 A charger?

Yes as a screen: 32 × 1.25 = 40. Still size the wire in Cable Size.

What size wire for a 60 amp EV charger?

The breaker rating alone is insufficient. Verify conductor material and insulation, terminal temperature ratings, wiring method, ambient and bundling adjustments, voltage drop, applicable code and OEM instructions in Cable Size and Voltage Drop. See also EV charger for home.

50 A vs 60 A for Level 2 / Tesla-class?

Match continuous amp setting: 40 A continuous → 50 A breaker; 48 A continuous → 60 A breaker.