Device wattage guides
Common household devices and practical wattage ranges for backup estimates.
View guide groupBackup Power Calculators
Home Power & Project Calculators
Free calculators for backup power, generators, portable power stations, solar charging, RV camping power, and home outage planning.
Popular calculators
- Generator Wattage Calculator
Estimate running watts, starting surge, and a practical generator size for selected backup loads.
- Portable Power Station Runtime Calculator
Estimate how long a portable power station can run a load after efficiency losses and reserve.
- Refrigerator Backup Time Calculator
Estimate refrigerator or freezer backup time using battery capacity, duty cycle, and inverter efficiency.
- Solar Panel Charging Time Calculator
Estimate solar charging time from battery size, charge target, panel watts, sun hours, and system efficiency.
- UPS Runtime Calculator
Estimate UPS runtime for routers, computers, NAS devices, and other small electronics.
Calculator category
Backup Power Calculators
Estimate power needs for outages, generators, battery stations, solar charging, UPS devices, CPAP backup, and RV or camping loads.
View categoryWhy use these calculators
- They use neutral formulas for planning estimates.
- Inputs and assumptions are visible instead of hidden.
- Results are estimates only and should be checked against device labels, manuals, and qualified guidance.
Safety note
These tools do not provide wiring instructions, medical advice, food safety guarantees, or emergency instructions. For safety-critical backup plans, consult qualified professionals and the equipment manufacturer.
New planning library
Guides for real outage questions
Compare appliance watts, outage durations, battery capacity, generator tradeoffs, solar charging, and UPS planning before using the calculators.
Outage planning guides
Home outage planning pages for different durations, seasons, and living situations.
View guide groupBackup power explainers
Plain-English explainers for batteries, generators, solar charging, UPS runtime, and sizing tradeoffs.
View guide groupBackup power tools
Start with a focused calculator, then compare related tools for a broader outage or camping plan.
Generator Wattage Calculator
Estimate running watts, starting surge, and a practical generator size for selected backup loads.
Open calculatorPortable Power Station Runtime Calculator
Estimate how long a portable power station can run a load after efficiency losses and reserve.
Open calculatorRefrigerator Backup Time Calculator
Estimate refrigerator or freezer backup time using battery capacity, duty cycle, and inverter efficiency.
Open calculatorSolar Panel Charging Time Calculator
Estimate solar charging time from battery size, charge target, panel watts, sun hours, and system efficiency.
Open calculatorUPS Runtime Calculator
Estimate UPS runtime for routers, computers, NAS devices, and other small electronics.
Open calculatorCPAP Battery Backup Calculator
Estimate CPAP backup runtime and nights from battery capacity, humidifier use, reserve, and efficiency.
Open calculatorRV / Camping Power Calculator
Estimate daily campsite energy use, trip battery needs, and optional solar recharge.
Open calculatorHome Outage Backup Planner
Plan 24, 48, or 72 hour backup needs for critical home loads using battery and generator estimates.
Open calculator