Skip to content

Inverter Size Calculator

Find what size inverter you need by ticking the loads that run at the same time. The calculator sizes on both numbers that matter (the continuous watts plus headroom, and the single largest starting surge against the inverter's peak rating), then shows the DC amps your battery cable and fuse must carry at 12, 24, or 48 V.

What runs at the same time?

W

Tick only what is on simultaneously. Motors and compressors show their starting surge; the inverter's peak rating (about 2× continuous on most units) has to clear the largest one.

Recommended inverter

2,000 W

continuous, pure sine wave · peak ≥ 4,000 W

Continuous, all on
1,410 W
With 25% headroom
1,763 W
Largest surge (refrigerator)
800 W
Sized by
continuous load
At 12 V this inverter pulls about 185 A DC from the battery at full rated load (163 A at your loads): the cable and fuse between battery and inverter must carry that.

Typical load values; check the labels on your own appliances. Peak ratings and how long they hold vary by model, and an oversized inverter wastes battery on idle draw: size for your real peak plus headroom.

Inverter, battery and charger in one box

For loads in the 1–2 kWh range, a portable power station is a complete inverter-and-battery system. Check its continuous output against the running watts above and its surge rating against your largest motor.

We earn a commission if you buy through links on this page, at no extra cost to you. It does not change what we recommend. See our affiliate disclosure. As an Amazon Associate I earn from qualifying purchases.

All power station picks

Frequently asked questions

Add the continuous watts of everything you will run at the same time, then check that your single largest starting surge fits inside the inverter's peak rating. Add 20–25% headroom to the continuous figure. A typical RV or small off-grid setup running a fridge, lights, laptop, and a few outlets lands on a 2,000 W inverter; a setup that has to start a well pump or an air conditioner is sized on the surge, which usually means 3,000 W or more.

Ask AI about this

Open an AI assistant with a question grounded in this page.

ChatGPTClaudePerplexityGoogle AIGrok

Rather not wire an inverter to a battery bank? A portable power station bundles the inverter, battery, and charger in one box, rated in the same continuous and surge watts. See the portable power station picks.

Related guides

Related calculators

Solar Loan Calculator

Estimate solar loan payments and the true cost of financing (including the dealer fee low-APR loans add) and check if the payment beats the electric bill it offsets.

Open calculator

Solar Panel Payback Calculator

Estimate how many years a solar system takes to pay for itself from the electricity it offsets, and its lifetime savings.

Open calculator

How Many Solar Panels Do I Need? Calculator

Find how many solar panels and what system size you need to cover your electricity use, from your annual kWh or your monthly bill.

Open calculator

Solar Panel Output Calculator

Estimate how much electricity a solar system produces per day, month, and year, with seasonal range and lifetime output after degradation.

Open calculator
Cite or link to this pageAPA · MLA · Chicago · HTML

Free to cite, quote and link. Copy a ready-made citation: the link back is all we ask.

APA

WattSimple. (2026, June 26). Inverter Size Calculator. https://wattsimple.com/calculators/inverter-sizing

MLA

"Inverter Size Calculator." WattSimple, 26 June 2026, https://wattsimple.com/calculators/inverter-sizing.

Chicago

WattSimple. "Inverter Size Calculator." Last modified June 26, 2026. https://wattsimple.com/calculators/inverter-sizing.

HTML link

<a href="https://wattsimple.com/calculators/inverter-sizing">Inverter Size Calculator</a> (WattSimple)

Sources & standards

This tool's methodology and data follow US standards and authoritative public datasets: