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
Heat pump water heater annual cost
$170
Standard electric tank annual cost
$936
Gas tankless annual cost
$218
Annual savings, heat pump vs standard tank
$766
Payback for heat pump premium
1.2
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How to use this
- 1Enter household hot water use (gal/day).
- 2Enter standard tank uef.
- 3Enter tankless uef.
- 4Enter heat pump water heater uef.
- 5Enter electricity price ($/kWh).
- 6Enter gas price (for tankless) ($/therm).
- 7Enter heat pump wh extra cost vs standard tank ($).
- 8Read your heat pump water heater annual cost on the right — it updates as you type.
- 9Hit Share to keep the scenario or send it to someone.
About this calculator
Compares annual energy cost across a standard tank, a tankless (on-demand), and a heat pump water heater based on your household hot water use and each technology's energy factor (EF) or uniform energy factor (UEF). Heat pump water heaters extract ambient heat like a mini refrigerator in reverse, typically hitting a UEF of 3.0+ (300% efficient) versus 0.6-0.7 for standard electric tanks and 0.95+ for tankless gas units. It also factors in the higher upfront cost of tankless and heat pump units to show simple payback against a standard tank replacement, which is the real decision point for most homeowners replacing a failed unit.
Worked example
Using the values the calculator loads with:
Inputs
- Household hot water use: 60 gal/day
- Standard tank UEF: 0.6
- Tankless UEF: 0.82
- Heat pump water heater UEF: 3.3
- Electricity price: 0.15 $/kWh
- Gas price (for tankless): 1.4 $/therm
- Heat pump WH extra cost vs standard tank: 900 $
Results
- Heat pump water heater annual cost: $170
- Standard electric tank annual cost: $936
- Gas tankless annual cost: $218
- Annual savings, heat pump vs standard tank: $766
- Payback for heat pump premium: 1.2
What each field means
Inputs
- Household hot water use (gal/day)
- The household hot water use used in the calculation, measured in gal/day. Starts at 60 gal/day so you have a working example on load.
- Standard tank UEF
- The standard tank uef used in the calculation. Starts at 0.6 so you have a working example on load. Accepted range: 0.4–0.95.
- Tankless UEF
- The tankless uef used in the calculation. Starts at 0.82 so you have a working example on load. Accepted range: 0.6–0.99.
- Heat pump water heater UEF
- The heat pump water heater uef used in the calculation. Starts at 3.3 so you have a working example on load. Accepted range: 2–4.5.
- Electricity price ($/kWh)
- The electricity price used in the calculation, measured in $/kWh. Starts at 0.15 $/kWh so you have a working example on load. Accepted range: 0.02–0.6 $/kWh.
- Gas price (for tankless) ($/therm)
- The gas price (for tankless) used in the calculation, measured in $/therm. Starts at 1.4 $/therm so you have a working example on load. Accepted range: 0.3–5 $/therm.
- Heat pump WH extra cost vs standard tank ($)
- The heat pump wh extra cost vs standard tank used in the calculation, measured in $. Starts at 900 $ so you have a working example on load.
Results
- Heat pump water heater annual cost
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Standard electric tank annual cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Gas tankless annual cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Annual savings, heat pump vs standard tank
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Payback for heat pump premium
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Why is a heat pump water heater so much more efficient?
It works like a refrigerator in reverse, pulling ambient heat from surrounding air and concentrating it into the tank rather than converting electricity directly into heat via resistance elements. That lets it deliver 3-4 units of heat per unit of electricity consumed, versus roughly 1-to-1 for a standard electric tank.
What's the catch with heat pump water heaters?
They need 700+ cubic feet of surrounding air space (typically a basement or garage, not a small closet) to draw heat from, they cool and slightly dehumidify that space as a side effect, and they cost $800-$1,500 more upfront than a standard tank plus sometimes need a dedicated 240V circuit if replacing a gas unit.
Is tankless actually cheaper to run?
Tankless gas units are efficient (no standby heat loss from a stored tank) but the savings versus a modern standard tank are usually modest — the bigger selling point is endless hot water and space savings, not dramatic bill reduction. The math favors heat pump electric over tankless gas almost everywhere except very cheap-gas regions.
How do UEF numbers translate to real savings?
UEF (Uniform Energy Factor) is the EPA/DOE-standardized efficiency rating printed on the EnergyGuide label — divide your hot water energy demand by UEF to get consumption, exactly like this calculator does. Always compare UEF, not the older EF rating, since the test method changed in 2017 and the numbers aren't directly comparable.
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.
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Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Water Heater Type Cost Comparison Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/water-heater-comparison
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/water-heater-comparison" target="_blank" rel="noopener">Water Heater Type Cost Comparison Calculator — RevenueLab</a> (2026).</p>
Source: [Water Heater Type Cost Comparison Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/water-heater-comparison) (2026).