WattRunTime.com
Language

Modem or fiber ONT Runtime Estimate

For home internet backup, include modem or ONT, router, and any mesh nodes as separate loads.

Use this load in the runtime calculator

Planning wattage range

8-25 W. Use a measured average when the device matters.

Planning default

12 W at 100% duty cycle, or about 12 W average load.

Confidence label

Estimated. Treat the result as a planning estimate, not a lab measurement.

1,024 Wh example

With 88% efficiency and a 10% reserve, about 811 Wh remains usable. At the default load, that is roughly 2d 19h.

Evidence behind these load values

Published device values and editorial calculator assumptions have different evidence. An editorial range is a starting input, not a measured category range; replace it with your device reading. Context links explain units or compatibility and do not prove the numbers. The check date records the evidence classification, not a new hardware test.

Evidence type
Editorial planning default
Source type
Official
Confidence
Estimated
Conditions
For home internet backup, include modem or ONT, router, and any mesh nodes as separate loads.
Swipe table sideways
Evidence behind these load values
ValueEvidence typeConditionsSource and datesConfidence
Planning wattage range8-25 WEditorial planning default
  • Operating state: Unknown
  • Output path: Unknown
  • Measurement interval: Unknown
No separately attributed sourceSource date: UnknownChecked:
estimated
Planning default12 WEditorial planning default
  • Operating state: Unknown
  • Output path: Unknown
  • Measurement interval: Unknown
No separately attributed sourceSource date: UnknownChecked:
estimated
Duty cycle100%Editorial planning default
  • Operating state: Unknown
  • Output path: Unknown
  • Measurement interval: Unknown
No separately attributed sourceSource date: UnknownChecked:
estimated

Device measurement guide

Use the measured average

Enter a steady watt reading or a full-cycle average in the runtime calculator. Use 100% duty cycle for an average that already includes on and off periods.

Device wattage (W)
Read watts after a steady load settles; record energy over time for a cycling load.
Duty cycle (%)
Average watts calculated from Wh divided by hours already include off-cycle time, so do not apply duty cycle again.
How to Measure Device Watts for Runtime Planning
Use this load in the runtime calculator

Verify your watts

  • Check the device label for running watts or input amps and volts.
  • Use a plug-in watt meter for AC loads when the result matters.
  • For cycling loads, measure long enough to capture on/off behavior.
Open wattage library

Check output path

  • AC inverter loads usually lose more energy than direct DC loads.
  • Keep reserve for cold weather, battery age, and load changes.
  • Do not treat label capacity as fully usable watt-hours.
Read the method

How to use this scenario

  • Start with 12 W if you do not have a watt-meter reading yet.
  • Modem or fiber ONT is treated as a continuous load, so runtime is sensitive to the real wattage you enter.
  • Keep at least a planning reserve because battery age, temperature, output path, and device settings can move the result.

Watch-outs

  • The scenario wattage is an estimate. Measure the real load before relying on it for outage, travel, or critical planning.

Sources

Use this load in the runtime calculatorCheck source wattage rangesFind a practical power station sizeCompare runtime by battery capacity

Related Scenarios

Compare nearby loads before assuming one wattage profile covers your setup.