Power Station for a Blackout

Quick answer: sizing a power station for a blackout

Using the preset above — a refrigerator (150 W), a router (10 W), two phone chargers (10 W each) and three light bulbs (10 W each), 210 W combined — a 1000 Wh power station at this site's typical 85% efficiency gives 1000 × 0.85 = 850 Wh of usable energy, and 850 ÷ 210 ≈ 4.05 hours, or 4h 3m of runtime, matching the calculator above at its defaults.

Your own number depends entirely on which devices you actually prioritize and for how long — swap the preset for your real essentials list, or switch to "What capacity do I need?" mode and enter your target hours directly. See the 8/12/24-hour examples further down for how quickly required capacity grows with longer outages.

What can you run during a blackout — and how to prioritize it

A common priority order for home backup power: refrigeration (food safety), any medical equipment, communication (a router and phone charging), and lighting — with heavier extras like a full entertainment setup or a dishwasher further down the list, if included at all. This calculator's preset reflects that core essentials combination rather than trying to power an entire home.

Add or remove devices in the calculator above to match your own household's priorities. Every device you add directly shortens the runtime of everything else, so a shorter, deliberate list generally outperforms a long one for the same power station. If your essentials list turns out to need more capacity than you have, cutting the lowest-priority item first — rather than reducing hours across the board — usually keeps the things that actually matter running longest.

How much power do common blackout devices use?

These are this site's existing planning wattages — average running watts, not a spec for your exact appliance — used consistently across every calculator here:

• Refrigerator (full-size): 150 W
• Mini fridge / cooler: 70 W — see the refrigerator comparison if you're deciding between the two
• Fan (standing/box): 50 W
• Wi-Fi router / modem: 10 W
• Phone charger: 10 W
• LED light bulb: 10 W (an LED strip is 20 W)
• Laptop: 65 W — see the laptop power station guide for sizing detail
• TV: 100 W
• CPAP machine: 40 W, without a heated humidifier — see the CPAP power station guide for device-specific detail and an important safety note

Watts vs. watt-hours: how to calculate the Wh you need

Watts (W) measure how much power your essentials draw at any given moment — the refrigerator, router, chargers and lighting running together. Watt-hours (Wh) measure how much total energy the power station has stored. This site's size-calculator formula uses both to solve for the capacity you need directly:

Required Capacity (Wh) = (Total Watts × Hours) ÷ Efficiency

Worked example using the preset above (210 W) for 8 hours: 210 × 8 ÷ 0.85 ≈ 1976 Wh, rounded up to 2000 Wh — matching what the Size Calculator would recommend for the same inputs. A higher Wh number always means more runtime for the same load, but only if the power station's continuous output (also measured in W) is high enough to run your essentials in the first place — use the calculator directly with your own essentials list and target hours rather than doing the math by hand.

How long do outages last, and what does 8, 12 and 24 hours actually require?

Outage duration varies enormously — from a momentary blip to multi-day events after severe weather. Rather than guessing a single number, it's worth sizing for a realistic worst case for your area and treating anything shorter as a bonus margin. The table below shows how required capacity scales with hours, using the preset's 210 W essentials combination and this site's 85% efficiency default:

• 8 hours: 210 × 8 ÷ 0.85 ≈ 1976 Wh, rounded up to 2000 Wh.
• 12 hours: 210 × 12 ÷ 0.85 ≈ 2965 Wh, rounded up to 3000 Wh.
• 24 hours: 210 × 24 ÷ 0.85 ≈ 5929 Wh, rounded up to 5950 Wh — well beyond a single typical portable power station, which is exactly why multi-day outages usually call for either a larger dedicated setup, solar recharging (see below), or a shorter, more deliberately prioritized essentials list.
• For reference, the refrigerator alone (150 W, no other devices) needs roughly 1450 Wh for 8 hours, 2150 Wh for 12 hours, or 4250 Wh for 24 hours — useful if food safety is your one non-negotiable priority and everything else is optional.

Refrigerators and startup surge

A refrigerator doesn't draw a flat 150 W the whole time it's plugged in — its compressor cycles on and off, and when it kicks on it briefly draws well above its running wattage. This site's planning figure treats that startup surge as roughly 3× the running wattage, the same figure used on the dedicated refrigerator page. This matters for whether a power station can start the fridge at all, not for how long it runs it once started — check your power station's rated surge/peak output against your specific fridge's startup behavior, since real surge varies by model.

A mini fridge (70 W) uses the same 3× planning figure for its own, smaller compressor, in case a smaller unit is part of your blackout plan instead of a full-size fridge.

Power stations vs. fuel generators for home backup

A genuine advantage of a power station for home backup: it produces no exhaust fumes and can be safely used indoors, unlike a gasoline or propane generator, which must always run outdoors and well away from windows and doors due to carbon monoxide risk. The tradeoff is capacity and recharge speed — a power station has a fixed, finite capacity per charge (see the 24-hour example above for how quickly that adds up), while a fuel generator can run continuously as long as fuel is supplied.

Many households use a power station for quiet, safe essentials and reserve a generator (if they have one) for larger, longer-duration needs. The two aren't mutually exclusive — a power station can also be recharged from a running generator or from solar (see below) to extend an outage well beyond a single charge. For the full comparison across power stations, power banks, solar generators and fuel generators, see Power Station vs Power Bank vs Solar Generator vs Generator.

Don't forget medical devices

If anyone in your household depends on a CPAP machine or other electrical medical equipment, plan for it explicitly and with extra margin rather than as an afterthought once other devices are already accounted for. This site's CPAP planning figure is 40 W without a heated humidifier — see the CPAP power station calculator for device-specific guidance and an important safety note: this is an electrical planning tool, not medical guidance, so confirm your exact machine's wattage and talk to your equipment provider about what backup plan is appropriate for your situation.

Solar recharging during an extended outage

For an outage that runs longer than a single charge can cover, solar panels let you recharge without grid power. The same formula used on this site's dedicated solar page applies: Recharge Hours ≈ Battery Capacity (Wh) ÷ (Panel Watts × Sunlight Factor), where the sunlight factor (commonly 0.6–0.7 for a clear day with well-positioned panels) accounts for a panel rarely hitting its full rated output in real conditions.

See the Solar Generator Runtime Calculator for the full recharge-time table and worked examples — most useful for multi-day outages where the 24-hour capacity figures above start to look impractical on a single charge.

Common mistakes when sizing for home backup

A few recurring mistakes lead people to buy the wrong power station for a blackout, or to be caught out mid-outage:

• Sizing only for a short outage and having no plan for a longer one — the 24-hour example above shows how quickly required capacity outgrows a single portable unit.
• Overlooking the refrigerator's startup surge rating — a power station can have plenty of Wh capacity yet still fail to start the compressor if its surge/peak wattage is too low.
• Treating the essentials list as fixed instead of prioritized — adding "nice to have" devices without checking how much runtime they cost the things that actually matter.
• Ignoring efficiency loss — the 85% default used here means usable energy is always somewhat less than the rated Wh capacity, not equal to it.
• Never testing the setup before an actual emergency, so a mismatched cable, a low surge rating, or a wrong wattage assumption only surfaces at the worst possible time.