{
  "name": "BackupEngineer default appliance wattages for backup power sizing",
  "publisher": "BackupEngineer",
  "url": "https://backupengineer.com/data/appliance-defaults.json",
  "calculator": "https://backupengineer.com/calculator",
  "license": "https://creativecommons.org/licenses/by/4.0/",
  "terms": "https://backupengineer.com/terms",
  "date_modified": "2026-10-26",
  "notes": [
    "Conservative planning estimates for sizing generators and batteries, not nameplate data. An appliance's nameplate or a plug-in meter is more accurate.",
    "additional_starting_watts is the brief motor surge ON TOP OF running watts.",
    "Modern (e.g. Energy Star) refrigerators often surge far less than the 2,200 W chart default.",
    "Please cite as: BackupEngineer, https://backupengineer.com/calculator"
  ],
  "method": {
    "running_watts": "sum(running_watts * qty)",
    "peak_watts": "running_watts + largest single additional_starting_watts (or the sum of all surges if motors may start together)",
    "energy_kwh": "sum(running_watts * qty * time_on_fraction) * outage_hours / 1000",
    "generator_derate": "fuel_factor * max(0, 1 - 0.035 * elevation_ft / 1000)",
    "generator_running_rating_w": "ceil(running_watts * (1 + headroom) / derate / 100) * 100",
    "generator_starting_rating_w": "ceil(peak_watts / derate / 100) * 100",
    "battery_usable_kwh": "energy_kwh / inverter_efficiency",
    "battery_nameplate_kwh": "battery_usable_kwh / depth_of_discharge",
    "inverter_continuous_kw": "running_watts * (1 + headroom) / 1000 (kVA = kW / power_factor)",
    "inverter_surge_kw": "peak_watts / 1000"
  },
  "assumptions": [
    {
      "name": "fuel_factor.gasoline",
      "value": 1.0,
      "source": "Reference rating"
    },
    {
      "name": "fuel_factor.propane_portable",
      "value": 0.9,
      "source": "Champion 201281: 6,750 W on propane vs 7,500 W on gasoline",
      "url": "https://www.championpowerequipment.com/product/201281-7500w-electric-start-dual-fuel-generator/"
    },
    {
      "name": "fuel_factor.standby_lp",
      "value": 1.0,
      "source": "Standby units are rated on LP"
    },
    {
      "name": "fuel_factor.standby_natural_gas",
      "value": 0.875,
      "source": "Default, user-editable. Generac air-cooled Guardian spec sheets: NG output from equal to LP (14 kW) to 12.5% lower (24 kW: 21,000 W NG vs 24,000 W LP).",
      "url": [
        "https://www.generac.com/globalassets/products/residential/standby-generators/spec-sheets/10-18kw-guardian-standby-generator-specsheet-en.pdf",
        "https://www.generac.com/globalassets/products/residential/standby-generators/spec-sheets/20-24kw-guardian-standby-generator-specsheet.pdf"
      ]
    },
    {
      "name": "altitude_derate_per_1000_ft",
      "value": 0.035,
      "source": "Champion 201281 owner's manual",
      "url": "https://www.championpowerequipment.com/wp-content/uploads/2025/09/201281-om-english.pdf"
    },
    {
      "name": "peak_method",
      "value": "running + largest single surge",
      "source": "Generac and Champion manuals",
      "url": "https://www.championpowerequipment.com/wp-content/uploads/2025/09/201281-om-english.pdf"
    },
    {
      "name": "headroom",
      "value": 0.2,
      "source": "A common design margin, not a code requirement"
    },
    {
      "name": "inverter_efficiency",
      "value": 0.9,
      "source": "Assumption (Tesla lists 89% solar-to-battery-to-home round trip for Powerwall 3)",
      "url": "https://energylibrary.tesla.com/docs/Public/EnergyStorage/Powerwall/3/Datasheet/en-us/Powerwall-3-Datasheet.pdf"
    },
    {
      "name": "depth_of_discharge",
      "value": 0.9,
      "source": "Assumption"
    },
    {
      "name": "power_factor",
      "value": 0.9,
      "source": "Assumption, used only to convert inverter kW to kVA"
    },
    {
      "name": "default_outage_hours",
      "value": 24,
      "source": "Calculator default (editable)"
    },
    {
      "name": "default_elevation_ft",
      "value": 1300,
      "source": "Calculator default: approximate Wichita, KS area elevation"
    },
    {
      "name": "heat_derate",
      "value": null,
      "source": "Not modeled; check the generator manual for hot-weather derating"
    }
  ],
  "appliances": [
    {
      "id": "refrigerator-freezer",
      "name": "Refrigerator/freezer",
      "running_watts": 700,
      "additional_starting_watts": 2200,
      "starting_watts_total": 2900,
      "requires_240v": false,
      "default_selected_quantity": 1,
      "default_time_on_fraction": 0.33,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "Virginia Cooperative Extension BSE-301 (DOE method), refrigerator time-on rule of thumb",
        "url": "https://ext.vt.edu/content/dam/pubs_ext_vt_edu/2901/2901-9014/BSE-301.pdf"
      }
    },
    {
      "id": "chest-or-upright-freezer",
      "name": "Chest or upright freezer",
      "running_watts": 500,
      "additional_starting_watts": 1000,
      "starting_watts_total": 1500,
      "requires_240v": false,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.33,
      "wattage_source": {
        "title": "GenSize generator wattage chart (starting watts converted to additional starting watts)",
        "url": "https://gensize.com/generator-wattage-chart/"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "furnace-fan-blower-1-2-hp-gas-furnace",
      "name": "Furnace fan blower (1/2 HP, gas furnace)",
      "running_watts": 875,
      "additional_starting_watts": 2300,
      "starting_watts_total": 3175,
      "requires_240v": false,
      "default_selected_quantity": 1,
      "default_time_on_fraction": 0.5,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "sump-pump-1-2-hp",
      "name": "Sump pump (1/2 HP)",
      "running_watts": 1050,
      "additional_starting_watts": 2150,
      "starting_watts_total": 3200,
      "requires_240v": false,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.1,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "well-pump-1-2-hp",
      "name": "Well pump (1/2 HP)",
      "running_watts": 1000,
      "additional_starting_watts": 2100,
      "starting_watts_total": 3100,
      "requires_240v": true,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.15,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "led-lights-about-10-bulbs",
      "name": "LED lights (about 10 bulbs)",
      "running_watts": 100,
      "additional_starting_watts": 0,
      "starting_watts_total": 100,
      "requires_240v": false,
      "default_selected_quantity": 1,
      "default_time_on_fraction": 0.5,
      "wattage_source": {
        "title": "GenSize generator wattage chart (starting watts converted to additional starting watts)",
        "url": "https://gensize.com/generator-wattage-chart/"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "wi-fi-router-modem",
      "name": "Wi-Fi router + modem",
      "running_watts": 25,
      "additional_starting_watts": 0,
      "starting_watts_total": 25,
      "requires_240v": false,
      "default_selected_quantity": 1,
      "default_time_on_fraction": 1.0,
      "wattage_source": {
        "title": "GenSize generator wattage chart (starting watts converted to additional starting watts)",
        "url": "https://gensize.com/generator-wattage-chart/"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "phone-laptop-chargers",
      "name": "Phone + laptop chargers",
      "running_watts": 75,
      "additional_starting_watts": 0,
      "starting_watts_total": 75,
      "requires_240v": false,
      "default_selected_quantity": 1,
      "default_time_on_fraction": 0.3,
      "wattage_source": {
        "title": "GenSize generator wattage chart (starting watts converted to additional starting watts)",
        "url": "https://gensize.com/generator-wattage-chart/"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "cpap-machine",
      "name": "CPAP machine",
      "running_watts": 60,
      "additional_starting_watts": 0,
      "starting_watts_total": 60,
      "requires_240v": false,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.35,
      "wattage_source": {
        "title": "GenSize generator wattage chart (starting watts converted to additional starting watts)",
        "url": "https://gensize.com/generator-wattage-chart/"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "television",
      "name": "Television",
      "running_watts": 500,
      "additional_starting_watts": 0,
      "starting_watts_total": 500,
      "requires_240v": false,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.2,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "microwave-1-000-w",
      "name": "Microwave (1,000 W)",
      "running_watts": 1000,
      "additional_starting_watts": 0,
      "starting_watts_total": 1000,
      "requires_240v": false,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.03,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "coffee-maker",
      "name": "Coffee maker",
      "running_watts": 1500,
      "additional_starting_watts": 0,
      "starting_watts_total": 1500,
      "requires_240v": false,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.03,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "space-heater",
      "name": "Space heater",
      "running_watts": 1500,
      "additional_starting_watts": 0,
      "starting_watts_total": 1500,
      "requires_240v": false,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.5,
      "wattage_source": {
        "title": "GenSize generator wattage chart (starting watts converted to additional starting watts)",
        "url": "https://gensize.com/generator-wattage-chart/"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "washing-machine",
      "name": "Washing machine",
      "running_watts": 1150,
      "additional_starting_watts": 2300,
      "starting_watts_total": 3450,
      "requires_240v": false,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.05,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "garage-door-opener-1-2-hp",
      "name": "Garage door opener (1/2 HP)",
      "running_watts": 875,
      "additional_starting_watts": 2350,
      "starting_watts_total": 3225,
      "requires_240v": false,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.01,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "window-ac-12-000-btu",
      "name": "Window AC (12,000 BTU)",
      "running_watts": 3250,
      "additional_starting_watts": 3950,
      "starting_watts_total": 7200,
      "requires_240v": false,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.5,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "central-ac-24-000-btu",
      "name": "Central AC (24,000 BTU)",
      "running_watts": 3800,
      "additional_starting_watts": 4950,
      "starting_watts_total": 8750,
      "requires_240v": true,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.5,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "heat-pump",
      "name": "Heat pump",
      "running_watts": 4700,
      "additional_starting_watts": 4500,
      "starting_watts_total": 9200,
      "requires_240v": true,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.5,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "electric-water-heater",
      "name": "Electric water heater",
      "running_watts": 2000,
      "additional_starting_watts": 1000,
      "starting_watts_total": 3000,
      "requires_240v": true,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.2,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    },
    {
      "id": "electric-range-8-inch-element",
      "name": "Electric range (8-inch element)",
      "running_watts": 2100,
      "additional_starting_watts": 0,
      "starting_watts_total": 2100,
      "requires_240v": true,
      "default_selected_quantity": 0,
      "default_time_on_fraction": 0.05,
      "wattage_source": {
        "title": "Generac RS5500/RS7000E portable generator brochure, wattage reference chart",
        "url": "https://uspowerpros.com/wp-content/uploads/Generac-portable-generators-RS5500-RS7000E-brochure.pdf"
      },
      "time_on_source": {
        "title": "BackupEngineer assumption (labeled guess; edit for your home)",
        "url": null
      }
    }
  ]
}