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HVAC made simple
WATER HEATER CALCULATOR
Gas vs. Electric Water Heater Cost Calculator
Compare the estimated operating cost of a natural-gas and electric resistance water heater using the same household hot-water demand and your local utility rates.
1. Household Hot-Water Use
Estimate how much hot water your household uses each day.
gal/day
Enter the approximate volume of hot water heated each day.
people
Used only for the optional quick hot-water estimate below.
2. Water Temperature
The greater the temperature rise, the more energy is required to heat the water.
°F
°F
Temperature Rise
65°F
120°F − 55°F = 65°F
3. Natural-Gas Water Heater
Enter your natural-gas price and an estimated overall energy-conversion efficiency for the comparison.
$
/ therm
Use the applicable variable gas cost from your utility bill
where possible.
%
This is a simplified energy-conversion assumption for the
operating-cost model. For a specific unit, use appropriate
manufacturer efficiency data.
$
/ month
Include this only if the charge would actually be avoided
by eliminating gas service or can reasonably be attributed
to the water heater.
4. Electric Water Heater
Enter your electricity price and electric resistance heating efficiency.
$
/ kWh
%
Electric resistance elements convert nearly all electrical
energy at the element into heat, although complete
water-heater operating efficiency also reflects standby
and distribution-related losses.
5. Optional Installed Cost Comparison
Add installed prices if you also want to compare simple long-term cost differences.
$
$
YOUR COST COMPARISON
Estimated Water Heating Costs
LOWER ESTIMATED OPERATING COST
Natural Gas
🔥
Natural Gas
Estimated Annual Cost
$0
Monthly Average
$0
Daily Average
$0
Annual Gas Use
0 therms
10-Year Energy Cost
$0
⚡
Electric Resistance
Estimated Annual Cost
$0
Monthly Average
$0
Daily Average
$0
Annual Electricity
0 kWh
10-Year Energy Cost
$0
Annual Cost Difference
$0
10-Year Cost Difference
$0
Useful Heat Needed
0 BTU/day
Same Hot-Water Demand — Different Purchased Energy
Useful Heat Needed Per Year
0 million BTU
Gas Energy Purchased
0 million BTU
Electricity Purchased
0 kWh
Utility-Rate Break-Even Comparison
These values show approximately where the two energy-cost estimates become equal under your entered efficiency assumptions.
Break-Even Electricity Price at Your Gas Price
$0.00/kWh
Break-Even Gas Price at Your Electricity Price
$0.00/therm
Installed Cost + 10-Year Energy Cost
Gas — Simple 10-Year Total
$0
Electric — Simple 10-Year Total
$0
What Does This Comparison Mean?
How the Calculator Works
Both systems are compared against the same useful water-heating requirement.
Water Heating Load
Gallons × 8.33 × temperature rise = useful BTU required
Gas Energy Required
Useful BTU ÷ gas efficiency = gas energy input
Gas Cost
Gas BTU ÷ 100,000 × price per therm
Electric Energy Required
Useful BTU ÷ electric efficiency ÷ 3,412.142 = kWh
Electric Cost
kWh × electricity price
Temperature Rise
Hot-water temperature − incoming-water temperature
⚠️ This Calculator Compares Gas With Electric Resistance Water Heating
A heat-pump water heater operates differently from a conventional electric resistance water heater and can use substantially less electricity under suitable conditions. Do not use the electric resistance results here as an estimate for a heat-pump water heater. A separate heat-pump water-heater cost calculator should use UEF or other appropriate performance assumptions.
Utility Bill Tip:
When comparing fuel costs, variable energy charges are usually the most useful starting point. A monthly gas customer or service charge should only be counted as a water-heating cost if switching away from gas would actually eliminate that charge, or if you have a reasonable basis for allocating part of it to the water heater.
Important:
This calculator provides educational cost estimates only. Actual
water-heating costs vary with hot-water consumption, incoming-water
temperature, thermostat setting, equipment efficiency, standby
losses, distribution losses, climate, utility rate structures,
tiered or time-of-use pricing, fixed charges, equipment condition,
installation and household behavior. Efficiency inputs in this
calculator are simplified assumptions and should not be treated as
equivalent to UEF or any particular standardized efficiency rating
unless appropriate for the comparison being made. Installed costs
vary by home and project. For accurate equipment comparisons, verify
manufacturer performance information and local utility rates and
consult a qualified plumbing or HVAC professional.