Water Heater Cost Calculator
What your water heater actually costs to run each year, what a different type would cost instead, and how quickly an upgrade pays for itself after the tax credit.
Estimates for comparison. Real usage varies enormously with household habits, incoming water temperature, and thermostat setting. Heat pump water heaters also need adequate air volume and a condensate drain — confirm placement with an installer before buying.
Heat pump water heaters commonly run $3,000–$5,000 installed; enter the extra over a like-for-like replacement if you're replacing a dead unit anyway.
Switching saves
Choose your household size
| Detail | Amount |
|---|---|
| What you run now | — |
| Heat pump water heater | — |
| Net cost after credit | — |
| Simple payback | — |
| Hot water used | — |
How Water Heating Cost Is Calculated
- Hot water used ≈ 14 gallons per person per day, plus a small base.
- Heat needed = gallons × 8.34 lb × 70°F rise × 365. Raising water from ~55°F to ~125°F is the standard assumption.
- Energy bought = that heat ÷ UEF. This is where the types separate — a heat pump's UEF above 1.0 isn't magic, it just moves heat that already exists in the air.
- Cost = energy × your rate, and payback = net cost after credit ÷ annual saving.
Worked example — 4 people, $0.17/kWh, electric tank at 0.90 UEF → heat pump at 3.5: 4,441 kWh/yr becomes 1,142 kWh/yr, cutting $755 down to $194. That's about $561 saved a year, with a $2,400 unit netting $1,680 after the credit → roughly 3 years payback.
Annual Running Cost by Type
Household of four, $0.17/kWh electricity and $1.60/therm gas:
| Type | UEF | Yearly cost | Notes |
|---|---|---|---|
| Electric tank | 0.90 | ~$755 | The expensive baseline |
| Gas tank | 0.64 | ~$341 | Cheap to run where gas is cheap |
| Gas tankless | 0.80 | ~$273 | No standby loss; higher install |
| Heat pump | 3.5 | ~$194 | Cheapest to run; needs air space |
When It Pays and When It Doesn't
- Replacing an electric tank — the strongest case in home energy. Roughly a third of the electricity, $500–$600 a year saved, 2–4 year payback with the credit. Few upgrades beat it.
- Replacing cheap natural gas — usually not worth it on running cost alone. The gap is small and the install is expensive.
- Buy at replacement time, not before. If your tank is dying anyway, compare the extra cost over a like-for-like swap — that's the real number, and it shortens payback dramatically.
- Location matters. A heat pump water heater cools and dries the room it's in. Garage or basement: fine, often welcome. Inside heated space in a cold climate: it steals heat your furnace replaces, eroding savings.
- Size up when switching. Recovery is slower than resistance elements — many installers go one tank size larger, or pick a model with a hybrid boost mode.
Frequently Asked Questions
What does a water heater cost to run?
Family of four: ~$755/yr electric tank, ~$341 gas tank, ~$194 heat pump, at $0.17/kWh and $1.60/therm.
Is a heat pump water heater worth it?
Replacing electric resistance, almost always — $350–$450/yr saved and a 30% credit capped at $2,000, paying back in 2–4 years. Replacing cheap gas, usually not.
What is UEF?
Uniform Energy Factor, on the EnergyGuide label. Electric ~0.90, gas tank ~0.60, gas tankless ~0.80, heat pump 3.0–4.0.
Is tankless cheaper to run?
About 25% less than a gas tank, but install is often double — payback on running cost alone can exceed a decade.
Does it cool the room?
Yes, and dehumidifies it. Fine in a garage or basement; costly inside heated space in winter. Needs ~700–1,000 cu ft of air.
What size do I need?
40 gal for 1–2, 50 for 3–4, 65–80 for 5+. Consider sizing up one step when switching to a heat pump.
References
- US Department of Energy — water heating and sizing guidance: energy.gov
- ENERGY STAR — heat pump water heaters and federal tax credits: energystar.gov
- US Energy Information Administration — residential energy prices: eia.gov