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GeneratorChecker

Portable Power Station Calculator

Estimate wattage, runtime, and best-fit portable power stations using OEM specs, surge-aware checks, and conservative safety buffers.

33 models 15 common devices Real-world derate + safety margin
1

Select your devices

or pick individually
2

How long do you need power?

Runtime Mode
Average Power Draw
131.1W
Energy Needed
1048.8Wh
Recommended
1724Wh+

Includes 30% real-world derate + 15% safety buffer

Free tool. No signup required. Learn about our methodology

Methodology Snapshot

How we calculate recommendations

Full methodology →

OEM Data

  • We source specs from manufacturer manuals whenever available.
  • Estimated values are explicitly labeled in reports and guides.

True Surge Analysis

  • Startup surge is evaluated separately from continuous running watts.
  • Recommendations avoid units that trip on peak demand at startup.

Spec-Based Results

  • Outputs are formula-based, not generated by generic templates.
  • We include derate and safety margin to reflect real-world use.

Why Most “What Size Generator Do I Need?” Answers Fall Short

Most online sizing advice says to add appliance wattage and buy a larger number. That skips the parts that decide whether a setup actually works in real use.

First, many devices do not draw full running power continuously. A refrigerator compressor cycles on and off. A CPAP is closer to 56W than the inflated values in many generic charts. This calculator uses duty-cycle adjusted loads from OEM specs where available, plus conservative engineering estimates when OEM values are not published.

Second, power and energy are different constraints. A 1,500W space heater stresses inverter output. A low-watt medical load may barely stress power, but still requires long runtime overnight. This calculator checks both: surge and running capability, then runtime suitability.

Third, nameplate battery capacity is not equal to usable delivered energy. Inverter losses, discharge limits, and battery aging reduce real output. We apply practical derates and a safety buffer by default, and you can refine them in Advanced Settings.

This produces recommendations based on electrical fit, not marketing numbers.

How to Read Your Results

Average Power Draw is the combined running load after duty-cycle adjustment. This is your continuous inverter demand.

Energy Needed is watt-hours required over your selected runtime window.

Recommended Wh+ is the target battery size after derate and safety buffer, so you avoid late-runtime dropoff.

Match cards include only generators that pass power, surge, and runtime checks. Ranking favors fit without excessive overkill.

Surge tier badges indicate startup behavior confidence:

  • Safe: surge margin is comfortably above peak need.
  • 30s Peak: startup is supported but uses more of the short peak window.
  • Surge Risk: startup demand is too close to generator limits.

If no model matches, the tool explains the limiting factor and next actions.

Preset Load Profiles

  • Camping Essentials: laptop, box fan, and Wi-Fi router.
  • Van Life Setup: laptop, coffee maker, and Wi-Fi router.
  • Home Backup: television, Wi-Fi router, and box fan.
  • Medical (CPAP): CPAP machine and Wi-Fi router.

Advanced Settings Reference

Depth of Discharge (50 to 100%)

How much of the battery you plan to use. Lower values are more conservative for battery longevity.

Inverter Efficiency (85% / 90% / 95%)

Represents DC to AC conversion efficiency under load.

Battery Age

Aging reduces deliverable capacity. Use this to model real-world units over time.

Solar Input (0 to 2,000W)

If charging while running loads, this reduces net battery drain.

FAQ

How do I know what size portable power station I need?

Start with average simultaneous load, then multiply by runtime. Correct for losses and add safety margin. Example: refrigerator at 207W running is about 83W average at 40% duty cycle, plus a 75W router and 56W CPAP gives 214W average. Over 8 hours: 1,712Wh raw. After derate and safety buffer: roughly 2,800Wh recommended.

What is the difference between watts and watt-hours?

Watts are instantaneous power. Watt-hours are energy over time. You need enough inverter power for peak load and enough stored energy for runtime.

Why is recommended capacity higher than energy needed?

Because usable energy is lower than rated capacity in real conditions. Inverter losses, discharge limits, and aging reduce delivered energy.

Can a portable power station run a refrigerator during an outage?

Usually yes, if startup surge is covered. Running watts are moderate, but compressor start can spike. This tool validates both.

Are recommendations influenced by affiliate partnerships?

No. Ranking is spec-fit based. Affiliate links are disclosed and do not change ranking order.

Where This Data Comes From

  • Device wattage and usage patterns: OEM manuals and DOE data where available, with conservative engineering fallbacks.
  • Generator specs: OEM running watts, surge watts, battery capacity, and voltage details.
  • Derates and buffers: Real-world assumptions to prevent under-sizing.
  • Ranking model: Fit and safety weighted scoring, no affiliate weighting.

See full methodology: Methodology.

No signup, no paywall, no personal data collection.