Estimate how long a new appliance takes to pay for itself through lower electricity use after rebates or credits.
Table of contents
How to use our Appliance Replacement Payback Calculator
- Enter Old appliance energy use and New appliance energy use in kWh per year, using EnergyGuide labels, a smart plug estimate, or a careful yearly estimate.
- Enter Electricity price from your bill in $ per kWh; if your bill has several charges, divide the total electric bill by total kWh for a fuller price.
- Enter New appliance cost before incentives, then enter Rebates or credits you expect as money you are likely to receive or use.
- Click Calculate and read Simple payback time first, then check Net upfront cost after incentives and 10-year net savings after cost.
- Sanity-check the result: Annual electricity savings should equal the difference between Old appliance yearly electricity cost and New appliance yearly electricity cost.
Definitions
kWh per year: Kilowatt-hours used in one year. Many appliance EnergyGuide labels include estimated yearly energy use in kWh [1].
Electricity price: The cost for each kWh of electricity. Your bill is usually the best source; EIA tables can help with broad price checks [2].
Rebates or credits you expect: Money back, store credit, utility rebate, or tax credit you expect to receive or use.
Net upfront cost after incentives: New appliance cost before incentives minus rebates or credits you expect.
Annual electricity savings: The old appliance yearly electricity cost minus the new appliance yearly electricity cost.
Simple payback time: The number of years of electricity savings needed to recover the net upfront cost after incentives.
10-year net savings after cost: Ten years of electricity savings minus the net upfront cost after incentives.
Common mistakes and quick fixes
Mistake: Entering watts instead of yearly kWh for Old appliance energy use.
Fix: Use kWh per year from the label or convert your estimate before entering Old appliance energy use.
Mistake: Using a national average instead of your bill for Electricity price.
Fix: Use your local Electricity price in $ per kWh when you have it, because rates can change the payback a lot.
Mistake: Leaving delivery, installation, parts, or haul-away out of New appliance cost before incentives.
Fix: Include the full out-of-pocket purchase cost if you want Simple payback time to reflect the real project cost.
Mistake: Entering a rebate you might not qualify for in Rebates or credits you expect.
Fix: Enter only incentives you expect to receive or a credit you can actually use.
Mistake: Treating a negative 10-year net savings after cost as an input error.
Fix: A negative 10-year net savings after cost means the energy savings do not recover the net cost within 10 years.
Limitations & Key Assumptions / Boundary Conditions
- The calculator compares electricity use only. It does not include gas use, water use, maintenance, repairs, financing, inflation, resale value, or changes in future electricity prices.
- The old and new kWh per year entries should describe similar use. If the new appliance is larger, used more often, or set differently, real savings may differ.
- Simple payback time is a cash recovery estimate, not a full life-cycle cost estimate.
- A 10-year net savings after cost value is a simple comparison window. It is not a promise that the appliance will last exactly 10 years.
- If Annual electricity savings is zero or negative, the calculator cannot show a normal energy-payback time because electricity savings do not recover the cost.
- If Rebates or credits you expect are larger than New appliance cost before incentives, Net upfront cost after incentives can be negative; this is kept instead of being forced to $0.
Methodology
Calculation steps
The calculator first estimates the yearly electricity cost for each appliance from yearly kWh and your entered electricity price.
old_annual_cost = old_kwh_year * electricity_rate
new_annual_cost = new_kwh_year * electricity_rate
It then subtracts the new yearly cost from the old yearly cost to find the signed yearly savings.
annual_savings = old_annual_cost - new_annual_cost
The upfront cost used for payback subtracts the incentive amount from the entered appliance cost. This value is not floored at zero.
net_upfront_cost = replacement_cost - incentive_amount
Simple payback is calculated only when yearly savings are positive. If yearly savings are positive and net upfront cost is zero or below, payback is shown as 0 years. If yearly savings are zero or negative, payback is not available.
payback_years = net_upfront_cost / annual_savings
The calculator also converts yearly savings to an average monthly amount and shows a 10-year comparison.
monthly_savings = annual_savings / 12
ten_year_net_savings = annual_savings * 10 - net_upfront_cost
Mini example
If the old appliance uses 700 kWh per year, the new appliance uses 400 kWh per year, electricity costs $0.17 per kWh, the appliance costs $900, and the expected incentive is $100, the old yearly electricity cost is $119 and the new yearly electricity cost is $68.
annual_savings = 119 - 68 = 51
net_upfront_cost = 900 - 100 = 800
payback_years = 800 / 51 = 15.69
ten_year_net_savings = 51 * 10 - 800 = -290
In this example, the appliance saves about $51 per year, takes about 15.7 years to pay back through electricity savings alone, and is still $290 short of payback after 10 years.