Sizing

How many watt-hours do I need?

Three numbers decide whether a power station fits: the watt-hours it must store, the watts it must deliver at once, and the surge it must supply when a motor starts. Choose the appliances below or add your own watts, hours and quantity. Check the connection too: enough energy does not make a station suitable for house wiring.

Your devices

Tick appliances from the device table, or add your own appliance using its label or a plug-in watt meter. Keep a preset only if it matches the equipment you plan to run.

Any picks earlier on this page use the starting appliances. Your changes update the calculator and its table below.

Units that fit the requirement above, sorted by price per Wh
Unit	Verdict	Wh	AC W	Surge W	lb	Chemistry	Price $	$ / Wh	Store
OUPES Mega 2	fits	2,048	2,500	5,400	48.5	LiFePO4	$699	$0.34	See it at OUPES
OUPES Mega 2 Pro	fits	2,048	2,500	–	48.8	LiFePO4	$699	$0.34	See it at OUPES
OUPES Mega 3	fits	3,072	3,600	7,000	83.3	LiFePO4	$1,099	$0.36	See it at OUPES
BLUETTI AC200L	fits	2,048	2,400	3,600	62.4	LiFePO4	$847	$0.41	See it at BLUETTI Check price on Amazon
BLUETTI Elite 100 mini	too little capacity	1,005	700	1,050	23.6	LiFePO4	$429	$0.43	See it at BLUETTI Check price on Amazon
BLUETTI AC180	too little capacity	1,152	1,800	2,700	35.3	LiFePO4	$499	$0.43	See it at BLUETTI Check price on Amazon
EcoFlow DELTA 3 Max	fits	2,048	2,400	–	44.8	LiFePO4	$899	$0.44	See it at EcoFlow
Jackery Explorer 2000 v2	fits	2,042	2,200	4,400	39.5	LiFePO4	$899	$0.44	See it at Jackery Check price on Amazon
EcoFlow RIVER 2 Pro	too little capacity	768	800	1,600	18.2	LiFePO4	$349	$0.45	See it at EcoFlow
EcoFlow DELTA 3 Ultra	fits	3,072	3,600	7,200	72.1	LiFePO4	$1,399	$0.46	See it at EcoFlow
Jackery HomePower 3000	fits	3,072	3,600	7,200	59.5	LiFePO4	$1,399	$0.46	See it at Jackery Check price on Amazon
Jackery Explorer 1000 v2	too little capacity	1,070	1,500	3,000	23.8	LiFePO4	$499	$0.47	See it at Jackery Check price on Amazon
BLUETTI Elite 400	fits	3,840	2,600	5,200	86	LiFePO4	$1,799	$0.47	See it at BLUETTI Check price on Amazon
Anker SOLIX C1000	too little capacity	1,056	1,800	2,400	28.4	LiFePO4	$500	$0.47	See it at Anker SOLIX Check price on Amazon
Jackery HomePower 3600 Plus	fits	3,584	3,600	7,200	77.2	LiFePO4	$1,709	$0.48	See it at Jackery Check price on Amazon
Anker SOLIX C2000 Gen 2	fits	2,048	2,400	4,000	41.7	LiFePO4	$1,000	$0.49	See it at Anker SOLIX
Anker SOLIX F3000	fits	3,072	3,600	7,200	91.5	LiFePO4	$1,500	$0.49	See it at Anker SOLIX Check price on Amazon
BLUETTI Elite 300	fits	3,014	2,400	4,800	58	LiFePO4	$1,499	$0.50	See it at BLUETTI Check price on Amazon
EcoFlow DELTA 3 Classic	too little capacity	1,024	1,800	3,600	26.7	LiFePO4	$529	$0.52	See it at EcoFlow Check price on Amazon
Anker SOLIX C1000 Gen 2	too little capacity	1,024	2,000	3,000	24.9	–	$530	$0.52	See it at Anker SOLIX Check price on Amazon
Anker SOLIX F3800	fits	3,840	6,000	9,000	132.3	LiFePO4	$2,200	$0.57	See it at Anker SOLIX Check price on Amazon
BLUETTI Elite 200 V2	fits	2,074	2,600	–	53.4	LiFePO4	$1,199	$0.58	See it at BLUETTI Check price on Amazon
DJI Power 500	too little capacity	512	1,000	–	16.1	LiFePO4	$299	$0.58	See it at DJI
Anker SOLIX F2600	fits	2,560	2,400	2,800	69.7	LiFePO4	$1,500	$0.59	See it at Anker SOLIX Check price on Amazon
EcoFlow DELTA 3	too little capacity	1,024	1,800	3,600	27.6	LiFePO4	$629	$0.61	See it at EcoFlow Check price on Amazon
BLUETTI Apex 300	fits	2,765	3,840	–	83.8	LiFePO4	$1,699	$0.61	See it at BLUETTI Check price on Amazon
Jackery Explorer 5000 Plus	fits	5,040	7,200	14,400	134.5	LiFePO4	$3,149	$0.62	See it at Jackery Check price on Amazon
Jackery HomePower 1000 v2	too little capacity	1,024	1,500	3,000	23.4	LiFePO4	$649	$0.63	See it at Jackery Check price on Amazon
DJI Power 2000	fits	2,048	3,000	–	48.5	LiFePO4	$1,299	$0.63	See it at DJI Check price on Amazon
Jackery HomePower 1000 Plus v2	too little capacity	1,024	1,800	3,600	23.8	LiFePO4	$669	$0.65	See it at Jackery Check price on Amazon
Anker SOLIX F3800 Plus	fits	3,840	6,000	9,000	136.7	LiFePO4	$2,600	$0.68	See it at Anker SOLIX Check price on Amazon
DJI Power 1000	too little capacity	1,024	2,200	4,400	28.7	LiFePO4	$699	$0.68	See it at DJI
OUPES Mega 1	too little capacity	1,024	2,000	4,500	27.8	LiFePO4	$699	$0.68	See it at OUPES Check price on Amazon
EcoFlow DELTA Pro 3	fits	4,096	4,000	8,000	113.5	LiFePO4	$2,799	$0.68	See it at EcoFlow Check price on Amazon
OUPES Exodus 700	too little capacity	576	700	1,200	13.9	LiFePO4	$399	$0.69	See it at OUPES Check price on Amazon
EcoFlow DELTA 3 Plus	too little capacity	1,024	1,800	3,600	27.6	LiFePO4	$719	$0.70	See it at EcoFlow
Jackery Explorer 1500 Ultra	too little capacity	1,536	1,800	3,600	38.6	LiFePO4	$1,079	$0.70	See it at Jackery Check price on Amazon
Jackery Explorer 300D	too little capacity	288	0	–	5.5	LiFePO4	$209	$0.73	See it at Jackery Check price on Amazon
BLUETTI Elite 100 V2	too little capacity	1,024	1,800	3,600	25	LiFePO4	$899	$0.88	See it at BLUETTI Check price on Amazon
Zendure SuperBase Pro 2000	fits	2,096	2,000	4,000	46.5	NMC	$1,999	$0.95	See it at Zendure Check price on Amazon
EcoFlow RIVER 3 Plus	too little capacity	286	600	1,200	10.4	LiFePO4	$279	$0.98	See it at EcoFlow Check price on Amazon
Jackery Explorer 300	too little capacity	294	300	500	7.1	Li-ion (unspecified)	$289	$0.98	See it at Jackery Check price on Amazon
Goal Zero Yeti 1500	too little capacity	1,505	2,000	3,600	52.8	LiFePO4	$1,500	$1.00	See it at Goal Zero Check price on Amazon
Goal Zero Yeti PRO 4000	fits	3,994	3,600	7,200	115.7	LiFePO4	$4,000	$1.00	See it at Goal Zero
Goal Zero Yeti 500	too little capacity	499	500	1,000	16.1	LiFePO4	$500	$1.00	See it at Goal Zero
Goal Zero Yeti 700	too little capacity	677	600	1,000	20.3	LiFePO4	$700	$1.03	See it at Goal Zero Check price on Amazon
OUPES Exodus 350	too little capacity	288	350	600	9.2	LiFePO4	$299	$1.04	See it at OUPES Check price on Amazon
Zendure SuperBase V4600	fits	4,608	3,800	5,000	121	LiFePO4	$4,999	$1.08	See it at Zendure
Zendure SuperBase V6400	fits	6,438	3,800	5,000	130	Li-ion (unspecified)	$6,999	$1.09	See it at Zendure
Goal Zero Yeti 300	too little capacity	297	350	600	13.7	LiFePO4	$350	$1.18	See it at Goal Zero Check price on Amazon
Zendure SuperBase Pro 1500	too little capacity	1,440	2,000	4,000	41.5	LiFePO4	$1,699	$1.18	See it at Zendure
Goal Zero Yeti 1000	too little capacity	998	2,000	3,600	35.3	LiFePO4	$1,200	$1.20	See it at Goal Zero
4Patriots Patriot Power Solar Generator 1200	too little capacity	1,030	1,200	2,400	28	LiFePO4	$1,499	$1.46	See it at 4Patriots
BLUETTI Elite 30 V2	too little capacity	288	600	–	9.5	LiFePO4	$449	$1.56	See it at BLUETTI Check price on Amazon
4Patriots Patriot Power Solar Generator 2200X	fits	2,240	2,200	4,400	57.5	LiFePO4	$3,500	$1.56	See it at 4Patriots
4Patriots Patriot Power Sidekick Solar Generator	too little capacity	299	300	360	8.4	LiFePO4	$500	$1.67	See it at 4Patriots Check price on Amazon

Also show the units that do not fit, with the reason

Step 1: watt-hours per device

Watts × hours = watt-hours. A device's draw comes from its label or its maker's spec sheet; for a cycling load like a refrigerator the useful energy figure is the average over a day, which can come from its yearly energy rating: kWh per year × 1,000 ÷ 8,760 hours = average watts. Add every device's watt-hours together, then multiply by the number of days. In a custom row, quantity multiplies the energy and peak power. Time running multiplies energy only: a pump cycling for part of the day still needs its full running and startup watts while it is on. An annual energy average cannot tell you those peak watts.

Step 2: inverter losses

The AC calculation divides device watt-hours by 0.85 as a planning allowance for conversion losses. This is not a measured efficiency for your station. DC and USB rows use the separate efficiency input, which starts with the same allowance. Their energy is calculated separately before adding it to the AC requirement. A compatible DC cable can avoid the AC inverter, but its converter still uses some power.

Step 3: headroom

Multiply by 1.2. The calculator adds 20% to the energy requirement as a planning margin. This allowance is fixed here; it is not a measured reserve or a promise that a particular appliance will finish the night.

Step 4: the two watt checks

Running peak is every device you might run at the same time, added up; it must sit under the unit's continuous AC rating. Start-up peak adds the largest extra startup demand to that running total. Copies in one custom row are assumed to start together; separate rows start one group at a time. If separate motors can start together, size for that combined startup demand. DC demand stays separate from the AC inverter check.

Step 5: match the voltage and connection

The normal fit result is for compatible 120 V plug-in appliances. Hardwired loads and 120/240 V split-phase loads keep their energy estimate, but get no confirmed fit. The home-backup connection guide explains the checks to take to an electrician. For DC equipment, match the voltage, connector, cable and shared port limits before buying.

Worked examples

A refrigerator for a day

Refrigerator (full-size, ENERGY STAR, ~18 cu ft top freezer)41 W × 24 h
Device Wh992
÷ 0.85 × 1.21,400 Wh
Running peak42 W
Start-up peak1,300 W

A CPAP with humidifier for two nights

CPAP machine (with heated humidifier)53 W × 8 h × 2 d
Device Wh848
÷ 0.85 × 1.21,198 Wh
Running peak53 W
Start-up peak104 W

A laptop and a phone for a working day

Laptop (MacBook Air, charging)40 W × 8 h
Smartphone charger (USB-C)20 W × 2 h
Device Wh360
÷ 0.85 × 1.2509 Wh
Running peak60 W
Start-up peak60 W

Amp-hours to watt-hours

Batteries are often rated in amp-hours (Ah) at a voltage; watt-hours are amp-hours times volts. A 100 Ah 12 V battery holds 1,200 Wh; a 100 Ah 24 V battery, 2,400 Wh; a 100 Ah 48 V battery, 4,800 Wh. Going the other way, a 1,024 Wh power station is about 85 Ah at 12 V or 20 Ah at 51.2 V, which is the nominal voltage of a 16-cell LiFePO4 pack. Compare batteries in watt-hours, never in amp-hours, unless the voltages match.

How long will 2,000 Wh last?

Capacity × 0.85 ÷ the device's watts, by the same arithmetic the calculator uses. On a 2,000 Wh unit: Refrigerator (full-size, ENERGY STAR, ~18 cu ft top freezer) (41 W) about 41 hours; CPAP machine (with heated humidifier) (53 W) about 32 hours; Laptop (MacBook Air, charging) (40 W) about 43 hours; TV, 50-inch LED / Crystal UHD (89 W) about 19 hours; Wi-Fi router (24 W) about 71 hours. Several devices at once share that capacity, so add their watts first. A 2,000 Wh unit is the mid-to-large boundary in thesize classes: enough for a refrigerator for about two days, or a working day of laptop, connectivity and a fridge with a margin.

The device draws the calculator uses

Each draw is the device manufacturer's rating, a US government energy figure, or a power station brand's published device table; "average" is a cycling load's daily average, "rated" the steady draw as specified. Your device may differ: read its label and change the hours or the device in the calculator.

Device draws
Device	Group	Draw W	Basis	Start-up W	Default h/day	Source
Box fan, 20 inch (Lasko Pro Power 20 inch box fan, model B20548, 3 speeds: 65 W on low, 90 W on high, and 90 W is used here as the high-speed figure. The same block gives 'Current 0.6 A to 1 A' and 'Voltage 120 V'. Worth noting for sizing: an inverter sees volt-amps, not watts, and 120 V x 1 A = 120 VA on high against the stated 90 W, a power factor of about 0.75 typical of a shaded-pole motor, so size against roughly 120 VA. Lasko publishes no starting figure. Their Cool Colors B20308 box fan is 56-83 W if a lower preset is wanted.)	home	90	rated	–	8	lasko.com
Electric blanket (full size) (Biddeford Blankets electric warming blanket with digital controller. Their listed electrical specifications give Twin 180 W, Full 180 W, Queen 130 W per side, King 180 W per side, all at 120 Vac. Resistive heating element, so no startup surge. Sunbeam was tried first as the task suggested but publishes no wattage anywhere: their old product URLs 404, their live catalog of 250 products mentions no wattage on any blanket, and three of their heated-bedding manual PDFs state only 'Plug power cord into a 110-120 volt wall outlet'.)	home	180	rated	–	6	biddeford-blankets.com
Refrigerator (full-size, ENERGY STAR, ~18 cu ft top freezer) (Running: ENERGY STAR Certified Residential Refrigerators dataset (US EPA open data), filtered to non-compact, non-built-in, 18-22 cu ft. 362 kWh/yr = 362,000 Wh / 8,760 h = 41.3 W average. Surge is from a manufacturer: Whirlpool Tech Sheet W11509412 Rev A (27 cu ft) lists 'Current locked rotor 11.3 A +/- 5%' on 115 VAC parts, so 11.3 A x 115 V = 1,299.5 W, rounded to 1,300 W (https://www.whirlpool.com/content/dam/global/documents/202103/tech-sheet-w11509412-reva.pdf). That same Whirlpool sheet independently cross-checks the average: 'Average Total Wattage' of 90-110 W while the compressor runs, x 45% run time at 70F ambient, is about 45 W, close to the 41.3 W derived from kWh/yr.)	home	41	average	1,300	24	data.energystar.gov
LED light bulb, A19 60 W equivalent (GE Classic LED, GEL SKU 67615 (LED10DA19/SWPW/4PK). The '60 Watt' in the product name is the equivalency claim, not the draw; actual draw is 10 W at 120 V for 800 lumens. GE's Basic line of the same A19 60 W replacement is 8.5 W for 700 lumens, so GE's range across lines is 8.5-10 W. Note that ENERGY STAR no longer certifies general-service bulbs; its only remaining bulb dataset covers connected/smart bulbs.)	home	10	rated	–	5	gelighting.com
Space heater, 1500 W (Lasko 754201 ceramic heater on its high setting. The same spec block gives 'Current 7.5 A to 12.5 A' and 'Voltage 120 V': 12.5 A x 120 V = 1,500 W confirms the high setting and 7.5 A x 120 V = 900 W the low setting. Resistive load, so no startup surge.)	home	1,500	rated	–	3	lasko.com
Sump pump, 3/10 HP submersible (Zoeller Technical Data Sheet FM2778 (Mighty-Mate series) model comparison chart: the M53 runs on 115 V, 1 phase, 9.7 A, 3/10 HP, which is the closest Zoeller builds to the 1/3 HP class. 9.7 A x 115 V = 1,115.5 W. The 230 V variants draw 4.8 A. Zoeller publishes no locked-rotor figure, so the surge is the top of Jackery's published starting range for a 1/3 HP sump pump, 'Sump Pump 1/3HP \| 800W \| 1,300-2,900W', a power-station-maker source.)	home	1,116	rated	2,900	2	zoellerpumps.com
TV, 50-inch LED / Crystal UHD (Samsung UN50U8000FFXZA, 50-inch Crystal UHD (2025). The same spec block gives Power Consumption (Max) 110 W, Power Consumption (Stand-by) 0.5 W, Power Supply AC110-120V~ 50/60Hz. Samsung's 43-inch U8000F is 85 W typical / 100 W max if a smaller preset is wanted.)	home	89	rated	–	4	samsung.com
Camp LED light set (4 chainable lights) (Goal Zero Light-a-Life Mini Quad USB Light Set: four chainable LED lights on one cord, NOT a decorative fairy-light string, for which no maker publishes a wattage. 6.3 W is Goal Zero's stated maximum for the whole 4-light set; their LED Rating row repeats '6.3W max, 110 Lumens (High), 30 Lumens (Low)'. Caution: Goal Zero's own figures are internally inconsistent, since 5 V x 1.7 A = 8.5 W and their per-light 1.7 W max x 4 = 6.8 W, neither of which equals the 6.3 W they state. Their stated 6.3 W is reported here rather than either computed value.)	camp	6	rated	–	4	goalzero.com
Circular saw, 7-1/4 in corded (DEWALT DWE575SB, listed on the same page as Voltage 120V, Corded. 15 A x 120 V = 1,800 W rated draw, which a saw only pulls in a hard cut. DeWalt publishes no startup figure, so the surge comes from Jackery's appliance wattage chart row 'Saw - Circular, 7 1/4in \| 900-1,400W \| 2,300W' (https://www.jackery.com/blogs/knowledge/appliance-wattage-chart), a power-station-maker source rather than a tool-maker one.)	work	1,800	rated	2,300	0.5	dewalt.com
Laptop (MacBook Air, charging) (Apple ships the M5 MacBook Air (13- and 15-inch) with a 40 W adapter rated to 60 W max. 40 W is the sustained rating; the machine draws less once its battery is full.)	work	40	rated	–	6	apple.com
Smartphone charger (USB-C) (Apple 20W USB-C power adapter as specified in the iPhone User Guide: Line Voltage 100 to 240 VAC, Output Voltage/Current 9 VDC/2.2 A. This is the adapter's maximum output, drawn only while the phone is actively fast-charging.)	work	20	rated	–	2	support.apple.com
Starlink Standard kit (dish + router) (Starlink's own Standard kit specification sheet. (75 + 100) / 2 = 87.5 W, the midpoint of the stated average band. Size for the full 100 W if the dish may run its snow-melt heater, which the same sheet rates at up to 40 mm/hour.)	work	88	average	–	12	starlink.com
Wi-Fi router (TP-Link Archer AX55 (AX3000 dual band Wi-Fi 6). 12 V x 2 A = 24 W. Important caveat: this is the bundled power adapter's rating, the ceiling the supply can deliver, not measured draw, and a real AX55 idles well below it. TP-Link publishes no typical-consumption figure, so 24 W is a safe upper bound for sizing but will understate runtime.)	work	24	rated	–	24	tp-link.com
CPAP machine (no heated humidifier) (ResMed publishes a typical-power figure only for the machine WITH its humidifier, so this configuration falls back to a power-station maker (Bluetti). Bluetti's quick-reference table gives 30-60 W for a basic CPAP: (30 + 60) / 2 = 45 W midpoint. The same table lists 'Startup/Peak Consumption \| Up to 100'.)	medical	45	rated	–	8	bluettipower.com
CPAP machine (with heated humidifier) (ResMed AirSense 10 AutoSet/Elite user guide, the 'device with humidifier' edition. 90W power supply unit, DC output 24V 3.75A. Peak 104 W recorded as the surge figure.)	medical	53	rated	104	8	document.resmed.com
Portable oxygen concentrator (Philips Respironics SimplyGo spec sheet. 120 W is the steady draw once the internal battery is charged; budget 150 W if the unit is also recharging its battery. AC input 100-240 VAC, 1.7 A max.)	medical	120	rated	–	12	documents.philips.com

Sources, with dates

Box fan, 20 inch: lasko.com, 2026-09-06 · "Energy Output 65 W to 90 W"
Camp LED light set (4 chainable lights): goalzero.com, 2026-09-06 · "USB (Male) Input: 5V, 1.7A (6.3W max)"
Circular saw, 7-1/4 in corded: dewalt.com, 2026-09-06 · "15 amp motor delivers power for even the toughest applications"
CPAP machine (no heated humidifier): bluettipower.com, 2026-09-06 · "Basic CPAP Machine | 30 - 60"
CPAP machine (with heated humidifier): document.resmed.com, 2026-09-06 · "Typical power consumption: 53W (57VA) / Peak power consumption: 104W (108VA)"
Electric blanket (full size): biddeford-blankets.com, 2026-09-06 · "Full Size - 180 Watts (120Vac)"
Refrigerator (full-size, ENERGY STAR, ~18 cu ft top freezer): data.energystar.gov, 2026-09-06 · ""model_number":"WHD-663FWESS1","type":"Top Freezer","capacity_total_volume_ft3":"18.0","annual_energy_use_kwh_yr":"362""
Laptop (MacBook Air, charging): apple.com, 2026-09-06 · "40W Dynamic Power Adapter with 60W Max"
LED light bulb, A19 60 W equivalent: gelighting.com, 2026-09-06 · "60 Watt replacement using only 10 Watts (800 lumens)"
Portable oxygen concentrator: documents.philips.com, 2026-09-06 · "Power consumption 150W while charging / 120W while not charging"
Smartphone charger (USB-C): support.apple.com, 2026-09-06 · "Minimum Power Output: 20 W"
Space heater, 1500 W: lasko.com, 2026-09-06 · "Energy Output 900 W to 1500 W"
Starlink Standard kit (dish + router): starlink.com, 2026-09-06 · "Power Consumption Average: 75 - 100 W"
Sump pump, 3/10 HP submersible: zoellerpumps.com, 2026-09-06 · "M53/M55 Single Auto 115 1 9.7 3/10 60"
TV, 50-inch LED / Crystal UHD: samsung.com, 2026-09-06 · "Power Consumption (Typical) 89 W"
Wi-Fi router: tp-link.com, 2026-09-06 · "Power | 12 V 2 A"
How the figures are checked

Questions buyers ask

My fridge's label says 120 W. Why does the table use less?

The label is the compressor's running draw; the compressor runs perhaps a third of the day, so the daily average is far lower. The average is what decides watt-hours; the running figure and the start-up surge are what decide the watt checks. Both are in the table.

Should I size for the biggest day or the average day?

For the day that matters most. An outage kit is sized for the longest outage you plan to cover with the fridge running; a camping unit for the heaviest evening. Then add the headroom and, if solar will refill it, check the unit's input against the solar page's arithmetic.

Does running from USB-C or 12 V change the answer?

Use a custom row and choose DC / USB cable. That separates its energy from the AC loads and uses the DC efficiency you enter. A DC converter still has losses, and the voltage, cable and shared port limits need checking before a station is suitable.

Is 20% headroom too much?

It is a fixed planning allowance, not a guarantee of extra runtime. The calculator multiplies the energy requirement by 1.2. If a load must run through the night, use its actual draw and leave enough capacity for the conditions you expect.

How many watt-hours is a 100 Ah battery?

Amp-hours × volts. 100 Ah at 12 V is 1,200 Wh; at 24 V, 2,400 Wh; at 48 V, 4,800 Wh. A power station's rating is already in watt-hours, so compare in Wh.