Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Lower total cost option
Generator
Generator total cost
$10,900
Battery backup total cost
$13,500
Difference
$2,600
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How to use this
- 1Enter generator install cost ($).
- 2Enter generator annual maintenance ($).
- 3Enter fuel cost per outage ($).
- 4Enter outages per year.
- 5Enter battery backup install cost ($).
- 6Enter battery annual maintenance/amortized replacement ($).
- 7Enter years.
- 8Read your lower total cost option on the right — it updates as you type.
- 9Hit Share to keep the scenario or send it to someone.
About this calculator
A standby generator costs less upfront and can run indefinitely on fuel, but requires ongoing maintenance and fuel costs during outages. A battery backup system costs more upfront, runs silently with no fuel, but has limited runtime unless paired with solar. This tool compares total cost of ownership over a chosen number of years, factoring in purchase/install price, annual maintenance, and estimated fuel or charging cost per outage.
Worked example
Using the values the calculator loads with:
Inputs
- Generator install cost: 6000 $
- Generator annual maintenance: 250 $
- Fuel cost per outage: 60 $
- Outages per year: 4
- Battery backup install cost: 12000 $
- Battery annual maintenance/amortized replacement: 150 $
- Years: 10
Results
- Lower total cost option: Generator
- Generator total cost: $10,900
- Battery backup total cost: $13,500
- Difference: $2,600
What each field means
Inputs
- Generator install cost ($)
- The generator install cost used in the calculation, measured in $. Starts at 6000 $ so you have a working example on load.
- Generator annual maintenance ($)
- The generator annual maintenance used in the calculation, measured in $. Starts at 250 $ so you have a working example on load.
- Fuel cost per outage ($)
- The fuel cost per outage used in the calculation, measured in $. Starts at 60 $ so you have a working example on load.
- Outages per year
- The outages per year used in the calculation. Starts at 4 so you have a working example on load.
- Battery backup install cost ($)
- The battery backup install cost used in the calculation, measured in $. Starts at 12000 $ so you have a working example on load.
- Battery annual maintenance/amortized replacement ($)
- The battery annual maintenance/amortized replacement used in the calculation, measured in $. Starts at 150 $ so you have a working example on load.
- Years
- The years used in the calculation. Starts at 10 so you have a working example on load. Accepted range: 1–25.
Results
- Lower total cost option
- Returned as a plain value and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Generator total cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Battery backup total cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Difference
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Which lasts longer during a multi-day outage?
A fueled generator can run as long as fuel is available, while a battery-only system without solar will deplete in hours to a day depending on load — pairing batteries with solar closes that gap.
Is a battery backup quieter and lower maintenance?
Yes — no combustion, no oil changes, no annual exercise cycles required, which is why upfront cost is higher but ongoing cost is lower.
Can I combine both?
Many homes run a battery for short outages and quiet operation with a generator as backup for extended outages — this calculator compares them as standalone choices.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Generator vs Battery Backup Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/generator-vs-battery-backup
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/generator-vs-battery-backup" target="_blank" rel="noopener">Generator vs Battery Backup Calculator — RevenueLab</a> (2026).</p>
Source: [Generator vs Battery Backup Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/generator-vs-battery-backup) (2026).