Every inverter generator gets a score from 0 to 100% built from seven factors, which maps onto the 5-point rating shown on the site (a 0% score would be 1.5 stars; a perfect score, 5). Each factor is scored against fixed reference points, not against the other products in the list, so adding a new model never moves another model’s rating. Generators are ranked within their size, by rated running watts on gasoline: small (under 2,500 W), mid-size (2,500 to 4,999 W) and large (5,000 W and up).
| Factor | Measures | Weight |
|---|---|---|
| Value | price per running watt | 30% |
| Quiet | rated noise at light load | 20% |
| Run time | hours on a tank at 25% load | 15% |
| Fuel options | gasoline, propane and natural gas | 10% |
| CO safety | carbon monoxide shutoff | 10% |
| Warranty | warranty length | 10% |
| Starting | electric or remote start | 5% |
Where the numbers come from
Running and starting watts, run time, noise, fuel options, safety features and warranty come from the maker’s spec page, manual or warranty terms, linked on every product page. Independent measurements, where a reviewer has published them, are shown in their own table.
Reference points by size
| Size | Price per running watt, scoring 0 → 100 | Run time at 25% load, 0 → 100 | Rated noise at light load, 0 → 100 |
|---|---|---|---|
| Small (under 2,500 W) | $0.60 → $0.20 | 4 → 14 hours | 62 → 48 dBA |
| Mid-size (2,500 to 4,999 W) | $0.55 → $0.15 | 6 → 18 hours | 66 → 50 dBA |
| Large (5,000 W and up) | $0.50 → $0.12 | 6 → 20 hours | 72 → 56 dBA |
The factors
Value is the lowest checked price divided by the rated running watts on gasoline. Prices are checked by hand and dated on every page. Small generators always cost more per watt, so each size has its own scale. A generator with no current price gets the neutral middle score.
Quiet is the maker’s rated noise in dBA at light load: the 25% load figure, or the “as low as” figure when that’s all the maker gives. The industry convention is to measure at 23 feet (7 m), though many makers don’t say. Every 10 dBA sounds about twice as loud, so a few decibels is a real difference at a campsite. Makers measure in slightly different ways and no one checks the claims, so this factor is marked estimated. Independent measurements are listed on product pages but taken at other distances and loads, so they aren’t mixed into the score. A generator whose maker gives no noise figure gets the neutral middle score.
Run time is the maker’s rated hours on a full tank of gasoline at 25% load. Where the maker rates run time at another load, it’s scaled to 25% assuming fuel use rises in step with load above idle, and the product page says so.
Fuel options scores gasoline only as zero, gasoline or propane (dual fuel) as 70%, and gasoline, propane or natural gas (tri-fuel) as full marks. Propane keeps for years without going stale and is easier to find after a storm; natural gas can run from a house’s gas line.
CO safety is full marks for a carbon monoxide sensor that shuts the engine off (sold as CO-Sense, CO Shield, CO Mind or similar), and zero without one. It doesn’t make indoor use safe, but it’s the best protection against a generator running too close to a house.
Warranty is the length of the maker’s residential warranty, from 1 year (zero) to 5 years (full marks), with the common 3 years in the middle.
Starting scores a pull cord as zero, push-button electric start as 80% and a remote fob or app start as full marks.
What isn’t scored
Weight, parallel capability, outlets and CARB compliance are shown and can be sorted or filtered, but aren’t scored. The RV ready list shows generators with a TT-30 outlet, the dual fuel list those that run on propane, the tri fuel list those that also run on natural gas, and the quiet list those rated at 55 dBA or less. Propane output, which is always lower than gasoline output, is listed where published. A generator is marked CARB compliant only when a California Air Resources Board Executive Order confirms it; makers’ own claims aren’t enough. Since model year 2024 that’s only Honda’s 50-state EU3200i and EU7000iS, and California now requires CARB certification for every portable generator sold there.
Missing data
If a figure isn’t published, that factor gets the neutral middle score (50) and the product page marks it as estimated.
Ties and discontinued models
Products are ranked by score within each size. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.