Generator Size Calculator and Noise Database
Nearly every "what size generator do I need?" answer online is a guess with a product link attached. Tick what you are actually running and this works it out properly — including the two things most calculators quietly skip: inverter losses, and the start-up surge that stalls an otherwise correctly sized generator. Then it filters the noise database below down to the units that will cover it, quietest first.
Generator noise and runtime database
Every generator we have reviewed, with the manufacturer's own noise and runtime rating and — the column nobody else prints — the load each figure was rated at. Tick your appliances above and the table filters to the units that will actually start and run them.
| Generator | Rated noise | Noise rated at | Running / starting | Rated runtime | Runtime rated at | Price |
|---|---|---|---|---|---|---|
| EcoFlow River 3 Plus Power Station Battery · about 10.4 lb | 30 dBA | load not stated “under 30 dBA” | 600 W 1,200 W starting | — | load not stated “depends entirely on draw” | Check price → |
| Honda EU2200i Petrol · about 47 lb | 48–57 dBA | idle to full, 23 ft “48 to 57 dBA at 23 ft” | 1,800 W 2,200 W starting | 8.1 hr | idle to full “3.2 to 8.1 hr per tank” | Check price → |
| Honda EU3000iS Super Quiet Inverter Petrol · about 131 lb | 50–57 dBA | idle to full “50 to 57 dBA” | 2,800 W 3,000 W starting | 19.6 hr | load not stated “up to 19.6 hr” | Check price → |
| WEN 56125i Super Quiet 1250-Watt Inverter Petrol · about 31.6 lb | 51 dBA | load not stated, 22 ft “51 dBA at 22 ft” | 1,000 W 1,250 W starting | 5 hr | at 1/2 load “about 5 hr at 50 percent load” | Check price → |
| Westinghouse iGen2550 Super Quiet Inverter Dual fuel · about 43 lb | 52 dBA | load not stated “as low as 52 dBA” | 1,900 W 2,550 W starting | 12 hr | load not stated “up to 12 hr per gas tank” | Check price → |
| Westinghouse 5000 Peak Watt Super Quiet Portable Petrol · about 105 lb | 52 dBA | at idle “as low as 52 dBA at idle” | 3,900 W 5,000 W starting | 18 hr | at 1/4 load “up to 18 hr at 25 percent load” | Check price → |
| Champion 2500-Watt Dual Fuel Portable Inverter Dual fuel · about 39 lb | 53 dBA | load not stated, 23 ft “53 dBA at 23 ft” | 1,850 W 2,500 W starting | 11.5 hr | at 1/4 load “up to 11.5 hr petrol, 34 hr propane at 25 percent load” | Check price → |
| WEN 56225i 2250-Watt Inverter Generator Petrol · about 49 lb | 53 dBA | at 1/4 load “53 dBA at 1/4 load” | 1,800 W 2,250 W starting | 9.4 hr | load not stated “up to 9.4 hr” | Check price → |
| Champion 2500-Watt Ultralight Inverter Generator Petrol · about 39 lb | 53 dBA | load not stated, 23 ft “53 dBA at 23 ft” | 1,850 W 2,500 W starting | 11.5 hr | load not stated “up to 11.5 hr” | Check price → |
| Yamaha EF2200iS Petrol · about 55 lb | 57–65 dBA | idle to full, 23 ft “57 to 65 dBA at 23 ft” | 1,800 W 2,200 W starting | 10.5 hr | at 1/4 load “up to 10.5 hr at 25 percent load” | Check price → |
| GENMAX GM2000i Ultra-Quiet Inverter Generator Petrol · about 34 lb | 58–60 dBA | load not stated “about 58 to 60 dBA” | 1,600 W 2,000 W starting | 10 hr | load not stated “up to 10 hr” | Check price → |
| Pulsar PGD40ISCO Ultra Light Quiet 4000W Petrol · about 46 lb | 59 dBA | load not stated “59 dBA” | 3,200 W 4,000 W starting | 4.5 hr | at 1/2 load “about 4.5 hr at 50 percent load” | Check price → |
| PowerSmart 3600-Watt Portable Inverter Petrol · about 50 lb | 59–70 dBA | idle to full “59 dBA idle, up to 70 dBA full load” | 3,200 W 3,600 W starting | 7.8 hr | at 1/4 load “3.1 hr full, up to 7.8 hr at 25 percent load” | Check price → |
| Pulsar PG2300iS Portable Inverter Generator Petrol | 59 dBA | load not stated “about 59 dBA” | 1,800 W 2,300 W starting | 4.8 hr | load not stated “up to 4.8 hr” | Check price → |
| Generac GP2500i Portable Inverter Generator Petrol · about 48 lb | 60 dBA | at 1/4 load “about 60 dBA at 1/4 load” | 2,200 W 2,500 W starting | 8 hr | load not stated “up to 8 hr” | Check price → |
| WEN 4800-Watt Dual Fuel RV-Ready Inverter Dual fuel · about 78.5 lb | 62 dBA | load not stated “62 dBA” | 4,000 W 4,800 W starting | 7 hr | at 1/2 load “about 7 hr petrol, 12 hr propane at 50 percent load” | Check price → |
| Champion 4000-Watt Dual Fuel RV Generator Dual fuel | 64 dBA | load not stated, 23 ft “64 dBA at 23 ft” | 3,000 W 4,000 W starting | 10 hr | at 1/4 load “up to 10 hr petrol, 25 hr propane at 25 percent load” | Check price → |
| Jackery Explorer 1000 v2 Power Station Battery · about 23.8 lb | — | load not stated “near silent” | 1,500 W 3,000 W starting | — | at full load “about 40 min at 1479 W” | Check price → |
How to read the “rated at” columns
Two generators in this table are both rated 52 dBA. One of them says at idle. Under the load you are actually going to put on it, that one is the louder machine, and nothing on the box tells you so. The same trick runs through the runtime column: a figure quoted at 25 percent load roughly halves when you plug in something real.
- Rated at idle, or load not stated — treat as a best case. Highlighted above.
- Rated at 1/4 load — the industry's favourite runtime figure. Expect meaningfully less.
- Rated at 1/2 load — a fair middle, and closer to how most people camp.
- A range, idle to full — the most honest format. The top number is the one your neighbours hear.
Distance matters as much as load, and it is rarely stated. A generator rated at 23 feet is quoted at about 7 metres. Move to 3 metres and it is meaningfully louder, which is roughly the distance from a pitch to the one next to it.
Every figure here can be checked against the maker’s own spec sheet, which is rather the point. More on our method: how we test. Links marked “Check price” are affiliate links — they cost you nothing and they are how the testing gets paid for.
How this is worked out
No black box. Every number above comes out of four steps, and you can check each one.
- Daily energy. Each appliance is watts × hours, which gives watt-hours. Fridges and cool boxes are entered as watt-hours per day instead, because a fridge's compressor cycles on and off — its nameplate wattage tells you almost nothing about what it consumes over 24 hours.
- Inverter losses. Anything running on mains plugs goes through an inverter, which is roughly 88% efficient. Skipping this is the most common mistake in camp power maths, and it undersizes the battery by about an eighth before you have started.
- Usable capacity. A battery's rated figure is not the figure you get to use. Lithium is taken at 90%; lead-acid and AGM at 50%, because discharging them past half ruins them quickly. This is why a 100Ah lead-acid battery and a 100Ah lithium one are not remotely the same purchase.
- Surge, for generators only. Motors and compressors pull several times their running wattage for a second or two at start-up. A generator is sized on the worst of those, on top of everything already running — which is why a generator that matches your running total on paper still stalls when the fridge kicks in.
What the calculator cannot know
The figures built in are typical draws, not measurements of your gear. Overwrite them with the numbers on your own labels wherever you have them — that is what the boxes are for. Three things move the answer more than people expect:
- Cold. Battery capacity drops in low temperatures, and a fridge works harder in a hot tent. A winter trip and a summer one are not the same load.
- Altitude and heat derate a generator. Petrol engines lose output as air thins and warms; the plate rating is a sea-level, mild-day figure.
- Anything that makes heat is in a different league. A kettle for ten minutes a day costs more energy than a full night of CPAP. If your list has a kettle, a hob or a fan heater on it, that is what is driving the answer — not the lights.
Where to go next
Once you know the number, the choice is between storing energy and generating it. Our power station reviews cover battery capacity and real usable watt-hours; the generator reviews cover running and starting watts, and how loud each one is while delivering them. If you are topping up as you go, the solar panel reviews cover what these panels actually produce rather than their peak lab figure.
Everything here is our own arithmetic, and we would rather show the working than ask you to take it on trust. More on how we work: how we test.