Running vs Starting Watts: Key to Sizing Right

What starting watts and running watts mean on a listing

A generator listing carries two watt figures. The running watts figure is what the unit can supply continuously while it works. The starting watts figure is a higher figure the unit can supply for a short moment; makers also call it surge watts or peak watts.

Motor-driven things draw extra power for the instant they start, and the starting figure exists to cover that brief draw. The running figure is the figure that matters for steady loads.

A kilowatt is 1,000 watts, and some listings write the figure in kilowatts. A 3,000 watt set reads as 3 kilowatts on some pages. The site writes watt figures in watts with a comma, so a 3,000 watt set reads as '3,000 watts'.

Read both figures on the listing. When a listing shows only one figure, that figure is usually the starting figure; the running figure appears on the maker's page for the model.

Why a title's first figure is usually the starting figure

A listing title begins with one watt figure, and that figure is usually the larger starting figure. The seller puts the number that draws the eye first.

The running figure may appear in the bullet list below the title or on the maker's page. Look for a second figure that is smaller than the first; that is the running figure.

A title that names two figures, such as a starting figure followed by a running figure, lets you compare at a glance. A title that names one figure still needs the maker's page read before any decision.

What the site's watts groups mean

This catalogue sorts generators into watts groups by the first figure in the listing title. Those groups are shopping categories, not promises about what a generator can run.

Small sets, mid sets and large sets are words the catalogue uses to separate the pool. The guide for each watts group compares the generators in that group by their stated details. See the best 3000 to 5000 watt generators and best 5001 to 9000 watt generators guides.

The stated details include the title's figures, the fuel type, the type of set, the start method and the CO feature. The watts group tells you where a unit sits in the range, not what it can power.

A watts group also sets the budget tier the guide covers. The price tier is read from the listing, and each guide states the tier it compares, without the site making price promises.

Why this site does not size a home

The U.S. Energy Information Administration reports that the average U.S. household consumes about 10,500 kilowatthours (kWh) of electricity per year, and that electricity use in homes varies widely. That average says nothing about the load in your home at an outage.

This site does not size a home because sizing depends on the appliances you want to power, the order they start and the wiring of the house. A licensed electrician and the maker, together, are the people to size a generator for a house. For a whole-house unit, see the best whole house generators guide.

The site can explain what starting watts and running watts mean on a listing and can point you to the guides that compare generators by their stated figures. It cannot tell you which generator runs your appliances.

The CPSC, CDC and EPA publish generator safety pages. The sources of this article list them, and this article does not repeat their guidance.

Comparing two listings by their stated figures

When two listings sit side by side, read the smaller running figure on each, not just the first figure in the title. A unit with a higher running figure can supply more continuous load than one with a lower running figure at the same starting figure.

Read the maker's page for each model. The maker's page carries the second figure, the fuel words and the start features. The listing and the maker's page together give the stated details for comparison.

The questions to ask the maker are about the running figure on your load and the conditions you run in. The maker publishes those answers in the manual and on the product page. For a list of portable sets, see the best portable generators guide.

The guides compare by stated details, not by price. Two generators in the same watts group and fuel type may sit in different budget tiers; the listing states the tier, and the guide explains how the pool is built.

Reading the bullet list and the maker's page

The bullet list below the title holds the details the seller chose to include: the fuel type, the start method, the outlets and the CO feature. A detail that is missing from the bullet list is still a detail a buyer must find before deciding.

The maker's page for the model shows the running watts figure, the fuel words and the features in the order the maker presents them. Reading the maker's page next to a listing is the way to compare the stated details of two generators. See also the best inverter generators guide for inverter models.

When a listing carries only the first figure, the running figure is on the maker's page. When a listing carries two figures, confirm on the maker's page which figure is running and which is starting.

What to pick for your situation

The table below matches shopping situations to the site's guides. Each guide compares generators by their stated details, and each guide explains how its pool is built.

What to pick for your situation

Questions

What is the difference between starting watts and running watts?

Running watts is the figure a unit can supply continuously while it works. Starting watts, also called surge or peak watts, is the higher figure the unit can supply for the brief moment when motor-driven things start. A listing title often shows the starting figure first and the running figure on the maker's page.

Which figure should I look at first?

Look at the running figure, because that is the figure the unit supplies steadily. The starting figure matters for the moment a motor-driven thing starts, but the running figure is the one that tells you what the unit can carry continuously. Read the maker's page to find the running figure when the listing does not show it.

Why does a listing show only one watt figure?

The one figure in a title is usually the starting figure, the larger number. The running figure appears in the bullet list or on the maker's page. A buyer who decides from the title alone reads the larger figure and may choose a set that cannot carry the steady load.

Can a wattage calculator size a generator for my home?

A calculator can add up the figures a buyer enters, but the load in a home depends on the appliances, their start order and the wiring. This site leaves that sizing question to a licensed electrician and the maker. The EIA reports that household electricity use varies widely, so an average cannot size your home.

What should I do if the running watts are not stated on the listing?

Read the maker's page for the model. If the running figure is still not stated, the maker's support is the place to ask before you decide. The site compares only the stated details that appear on the listing and the maker's page.