How long will a 5000W generator run on 5 gallons of gas?

At 50% load (2,500W), a 5,000W generator typically consumes about 0.7 gallons per hour, giving you roughly 7 hours on 5 gallons. At 75% load, expect about 5 hours.

How long will a 10 kWh battery last during an outage?

At 1,000W average load with 80% depth of discharge, a 10 kWh battery lasts about 8 hours. Running essentials only (500W), you'd get 16 hours.

How much gas do I need to stock for a 3-day outage?

A 5,000W generator at 50% load consumes about 0.7 gal/hr. For 72 hours at 8 hours/day of use, you'd need about 50 gallons. Store fuel safely with a stabilizer for extended storage.

Quick answer: A 10 kWh battery at 80% depth of discharge powering 1,000W of load runs roughly 8 hours; a 5,000W generator at 50% load and 5 gallons of fuel runs about 7 hours.

RV & Backup Power

Outage Runtime Estimator

How long will your generator or battery last? Enter your equipment specs and connected load for an accurate runtime estimate and fuel planning data.

Power source

Generator preset

Generator running watts

Fuel tank size

gal

Load input method

Load: 2,500 W

100 W10,000 W

Estimated runtime

3h 47m

at 2,500 W load

Fuel details

Consumption rate1.32 gal/hr at 50% load

Fuel planning:3-day supply: 95.0 gal · 1-week: 221.7 gal

Compare generator vs battery →

How we calculate outage runtime

For batteries, runtime is usable capacity divided by connected load. For generators, fuel consumption is estimated from the load-to-rated-wattage ratio using a standard efficiency curve.

Battery Runtime (hrs) = Capacity (kWh) × DoD ÷ Load (kW)

Generator fuel consumption is calculated as rated fuel use × load factor, where load factor = connected watts ÷ rated watts.

Frequently Asked Questions

How long will a 5000W generator run on 5 gallons of gas?: At 50% load (2,500W), a 5,000W generator typically consumes about 0.7 gallons per hour, giving you roughly 7 hours on 5 gallons. At 75% load, expect about 5 hours.
How long will a 10 kWh battery last during an outage?: At 1,000W average load with 80% depth of discharge, a 10 kWh battery lasts about 8 hours. Running essentials only (500W), you'd get 16 hours.
How much gas do I need to stock for a 3-day outage?: A 5,000W generator at 50% load consumes about 0.7 gal/hr. For 72 hours at 8 hours/day of use, you'd need about 50 gallons. Store fuel safely with a stabilizer for extended storage.

Embed this calculator

Drop the Outage Runtime Estimator into your own site. Free for non-commercial use with attribution.

iframe

<iframe
  src="https://powersizing.com/backup/outage-runtime-estimator?embed=1"
  width="100%"
  height="560"
  frameborder="0"
  loading="lazy"
  title="Outage Runtime Estimator"
></iframe>
<p>Powered by <a href="https://powersizing.com">PowerSizing</a></p>

Keep the attribution link visible — it's the only thing we ask in exchange for the free tool.

Live preview

Outage Runtime Estimator

— input

—result

Reviewed April 2026

Methodology and source note

PowerSizing calculators use shared formulas, documented assumptions, and current planning inputs that are summarized on the methodology page. Use these tools for first-pass planning, comparison, and sanity checks, then confirm local code, pricing, utility tariff, and installer specifics before you buy equipment.