Sizing and cost calculators

Generator size chart

A generator size chart is only useful if you can trace each number. This chart shows where every figure came from. It also shows which figures are missing.

The chart covers portable generators, battery power stations, standby units and transfer hardware. Every numerical row names its model and source.

A generator size chart links power figures to their evidence. This one starts with generic Honda appliance estimates, then lists published supply ratings. Estimates are labeled, and exact appliance models stay unknown. Your own nameplates must supply the final load data before you confirm a size.

Generator size chart: approximate appliance demand

These rows come from Honda's US wattage estimation guide. The source gives generic estimates, not readings from your exact appliance. Its page is undated. The model field stays UNKNOWN.

A blank voltage cell is not proof of 120 V. Check your own nameplate before sizing a source.

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Carry a checked scenario to the worksheet

Use the refrigerator's upper running estimate only as an example. Add a bulb whose label says 60 W. With one of each, running demand is 252 W. The fridge's start gap is 1,200 minus 192, or 1,008 W.

Add that gap to 252 W: starting demand is 1,260 W. This is derived arithmetic from generic estimates. It is not proof of fit for your fridge.

The size calculator starts with that editable example. Replace both rows with your own checked loads. Keep total starting watts distinct from the extra start gap. If voltage or starting demand is unknown, compatibility stays unknown even when the subtotal looks small.

Before adding a second fridge or freezer, record both units. They may start together. Use the simultaneous scenario if you cannot control that overlap. Enter quantity in whole units, and count each motor's running watts once.

Do not paste a maker's generic range into a field that needs one exact value without naming the assumption.

How to read this generator size chart

This page includes published generator ratings, generic appliance estimates and worked arithmetic. These are different kinds of evidence. The matrix explains their scope and use.

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The supply tables below use published maker ratings. None was measured by this site. The appliance estimates above remain estimates even though a maker published them. The worked example totals are derived arithmetic, not measured demand.

Running watts are the steady power a load uses once it is going. Starting watts are the higher total some motor loads need for a moment at startup. A generator's rated figure covers steady output. Its maximum or peak figure covers short demands.

Our page on running wattage vs starting wattage explains the difference in more depth.

Generator size chart: portable engine and inverter models

These figures describe each generator's own output. They do not show what any appliance will draw from it.

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DuroMax rating sources. The current XP13000HXT manual, page 80 lists running/starting watts of 10,500/13,000 on gasoline, 10,000/12,500 on propane and 9,000/11,250 on natural gas. The current US product table agrees.

The manual filename marks revision 02072025. The older sales sheet, page 2 gives lower propane and natural-gas ratings. These are current document figures, not proof that every unit has those ratings.

Match your unit's label and manual revision before sizing loads. Starting watts do not promise a motor will start or state how long peak output lasts.

Champion lists 9000 W starting on all three fuels. Running ratings remain fuel-specific. DuroMax rows use its current manual, page 80. An older DuroMax sheet differs, so check your unit's revision.

What the fuel rows show

Some of these models list output for more than one fuel. On the Champion 201176, the WGen11500TFc and the XP13000HXT, running watts drop from gasoline to propane. They drop again on natural gas. The Champion 201278 and iGen2550DFc list lower propane running watts too.

This pattern belongs to these listed models only. It is not a rule for every dual-fuel or tri-fuel generator. The figures also say nothing about emissions, upkeep or engine life. They only show published output on each fuel.

Size around the fuel you will actually use. A gasoline rating does not apply when the same unit runs on propane or natural gas. Fuel supply is a separate question. Gasoline availability varies locally, and no fuel supply is guaranteed.

What the voltage and outlet columns show

The Honda, Champion 201278 and iGen2550DFc rows list 120 V output. The Champion 201176, WGen11500TFc and XP13000HXT list 120/240 V. A 120 V source cannot supply a 240 V load. An adapter cannot create a missing voltage.

A 120 V output does not rule out every transfer product, though. The TF152W in the hardware table is a 125 V, one-circuit part. Whether any pairing works depends on exact product documents.

The iGen2550DFc page lists an RV TT-30R outlet. It also says the unit is not transfer-switch-ready. An RV receptacle is not proof of approved home transfer use.

The WGen11500TFc page describes pairing with a specific Westinghouse WATS200 automatic transfer system. This chart does not compare that system's full requirements. Automatic operation stays unresolved here without exact compatible documents. Even with automation, an engine generator still needs safe outdoor placement.

Battery power stations

These units store energy instead of burning fuel. Their key figures are stored energy in watt-hours and rated AC output in watts. The two units measure different things.

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The BLUETTI page lists solar and AC recharging. A separate EcoFlow 700 variant has its own 716 Wh figure. That figure does not apply to the RIVER 2 Pro row.

The current AC specifications list 3600 W surge for the BLUETTI, 4400 W for the Jackery and 1600 W for the EcoFlow. Check the surge duration and exact appliance start separately. This chart makes no runtime, battery life or medical device claim.

Home standby generators

Standby ratings differ by fuel on the same unit. This chart keeps each fuel rating separate.

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On these three models, the propane rating is higher than the natural gas rating. That gap belongs to these listed units. It does not mean natural gas is unlimited or that one fuel suits every home.

The KOHLER page lists an automatic transfer switch as sold separately on a listed option. It also says model documents must confirm the exact order setup. For the Cummins unit, we used the maker's brochure for the rating.

Transfer switch hardware

These rows show what each kit contains. They do not show whether a kit fits any panel, generator or home.

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The TF152W's 1875 W figure is a limit for that part. It is not the demand of any appliance. Its 125 V rating is a component rating, not a voltage for every appliance.

Generac's support article lists 10 circuits for the 6853. It describes an upgrade for standby units up to 11 kW, subject to system fit. These three kits are manual equipment. Any upgrade needs its own compatible system documents.

Turning generator size chart rows into a load scenario

A generator row is only the supply side. The load side comes from your own appliance nameplates. The first table supplies generic Honda appliance estimates. Exact model demand still comes from your own labels and documents.

Start with R. R is the total running watts of everything that runs at the same time. Include every motor load's running watts in R.

Next, find each motor load's gap. The gap is its total starting watts minus its running watts. Treat any negative gap as zero.

If only one load starts at a time, use this rule. S equals R plus the largest single gap. If loads can start together, use the second rule. S equals R plus the sum of each gap times how many of those loads start at once.

Do not add a full starting figure on top of R. That counts the same motor twice. Do not leave a motor's running watts out of R either. Do not assume motors never start together.

Then compare S with a generator's maximum figure for your fuel. Compare R with its rated running figure. A passing number is not a full compatibility result. Voltage, receptacle, transfer equipment and runtime still need separate checks.

Units that often get mixed up

Watts measure power. Watt-hours measure stored energy. Watts times hours gives watt-hours, and 1000 watts equals 1 kilowatt.

Some labels list volts and amps. For AC, volts times amps gives volt-amps. That equals watts only when the power factor is known. Do not treat a volt-amp figure as watts without that value.

Electric watts also say nothing about gas flow. Fuel pressure and flow need their own check from the exact product documents.

Once you have checked R and S from your nameplates, carry them to what size generator do I need. That page walks through the full sizing task.

Source, method and limitations

How the chart was built

Every row comes from a current US manufacturer page or document. Each row links the source. We kept model numbers where the maker listed them.

When a maker listed no figure, the cell says so. We preserved published supply figures. The appliance example uses a labeled upper estimate, not a measurement.

Spec sheets change over time. If you read this much later, open the linked page for each row before you buy.

What this chart cannot tell you

This chart includes a small set of labeled generic estimates. Refrigerators, furnaces, pumps and air conditioners vary by model. Their running and starting demand must come from their own nameplates or documents.

A rated output does not prove a generator can start a given motor. That needs the motor's running and total starting figures, plus voltage, receptacle and duration data. Without them, no row here proves a named appliance will fit.

The chart also leaves out noise comparisons, warranties, lifespan and fuel storage time. The records we used did not support those claims across models.

Safety and installation limits

The CPSC says to run portable engine generators outdoors. Keep them at least 20 feet from homes with exhaust pointed away. Never run them indoors or in a garage, even with the doors open.

A CPSC safety alert adds more steps. Use a dry surface and follow the maker's approved rain setup. Shut down and let the engine cool before refueling. Never backfeed a wall outlet.

Use CO alarms and get to fresh air if one sounds.

Standby clearances come from each unit's own manual and local rules. Generac's connection guidance says the generator, switch, inlet, panel and circuits must match. Installation and service belong to licensed electrical trades. Gas work belongs to licensed gas trades.

Never modify wiring, gas lines or neutral bonding, or bypass a safety device.

Generator size chart FAQs

Does this chart include appliance wattage?

Yes. The first table gives Honda's generic estimates with the source. They are not measured values for your own equipment. Exact model fields stay UNKNOWN.

Read each device's nameplate or documents before sizing. Keep running demand and total starting demand separate, then use the calculator for your scenario.

Why are some cells blank or marked as not listed?

A blank cell means the maker does not list that value. The DuroMax rows use its current manual. An older sheet differs, so check your unit's revision. Champion lists 9,000 starting watts on each fuel for the 201176. Keep each number with its source.

Can I compare a power station row with a generator row?

Only on rated AC output in watts. Battery capacity in watt-hours is stored energy, not power. A 2048 Wh battery and a 2400 W output describe different things. The declared surge figures still need their duration and operating conditions checked against the exact appliance start.

Do I still need a transfer switch check after using this chart?

Yes. A chart row shows output, not home connection approval. The generator, switch, inlet, panel and circuits must all match per exact product documents and local rules. The iGen2550DFc page says it is not transfer-switch-ready.

Installation belongs to licensed electrical trades, not to the homeowner or this chart.

Primary documents

• CPSC portable engine generator placement
• Honda EU2200i exact US specifications
• Honda EU3200i exact US specifications
• Honda EU3000iS exact US specifications
• Champion 201176 operator's manual specifications
• Westinghouse iGen2550DFc exact US specifications
• BLUETTI AC200L exact US specifications
• Jackery Explorer 2000 v2 exact US specifications
• Generac Guardian 26 kW specification sheet
• Westinghouse WGen11500TFc US product specification
• DuroMax XP13000HXT current US specification
• EcoFlow RIVER 2 Pro US 768 Wh model
• KOHLER 20RCA current specification
• Cummins QuietConnect current home-standby brochure
• Reliance Controls six-circuit transfer kit
• Generac manual transfer switch support article
• Reliance Controls TF152W manufacturer manual (PDF)
• Champion 201278 dual-fuel inverter
• CPSC generator dry-surface and refueling safety
• Power and energy units
• Generac home connection safety
• Honda US approximate appliance demand
• BLUETTI AC200L cycle/storage record
• Jackery Explorer 2000 v2 cycle record
• EcoFlow RIVER 2 Pro cycle/storage record
• Generac G007290-0/G007291-0 published fuel consumption

Generator size chart Verdict

This generator size chart is a screening tool built from published manufacturer figures. Every row has a model and source. Its appliance rows are labeled estimates; supply rows are published specifications.

If you already know your fuel and voltage, the matching rows narrow your choices quickly. Use the row for your selected fuel. A gasoline figure does not describe propane or natural gas output. A 240 V load requires a source with documented 240 V output.

Until you read your appliance nameplates, the chart cannot finish the job. Build R and S from those labels first. Then confirm receptacle, transfer equipment and safe placement through exact documents and licensed trades.

Continue your backup plan

• What size generator do I need
• Running wattage vs starting wattage