Gas vs Electric Water Heater: Lifetime Cost Compared

What does $1,939.94 mean?

It means that over 10 years, heating 50 gallons of water a day with a gas storage-tank heater costs $1,939.94 less than heating it with an electric one — $4,343.55 against $6,283.48, install, energy and maintenance all counted. The gas heater costs $300 more to install, but it saves $223.99 a year after maintenance, so it catches up in year 2 and keeps saving after that. The heat itself is 9.89 MMBtu a year, and the gas heater needs 159.57 therms to deliver it against 3,052.18 kWh for electric — gas energy is cheaper per unit of heat, and that is what decides the lifetime winner.

Three things to check before you trust the number

The inlet and set temperatures are typical averages. 55 °F inlet and a 120 °F set point are typical US averages — colder inlet water or a hotter set point raises both bills. If your cold water arrives at 40 °F in winter, the heat needed rises by more than a fifth, and both annual costs rise with it. The gap between the two heaters grows too, because the dearer fuel carries more of the extra load.

EF ratings are lab figures. The ratings are measured under standard test conditions, and real efficiency depends on usage pattern, insulation and climate. A gas heater in a cold garage loses more standby heat than one in a warm utility room; an electric heater in a household that uses hot water in short bursts cycles more and wastes more. If your usage is nothing like the lab pattern, the real gap will differ.

The install gap decides the break-even year. Gas saves $223.99 a year after maintenance, so it needs just over one year to recover a $300 install gap — year 2. Raise the gas install to $3,100 and gas only just wins inside 10 years; raise it past that and electric wins. Get two itemised quotes before you decide: the install gap moves the answer more than any other single input.

Worked example

On the defaults: 50 gallons a day; gas $1.50 a therm, EF 0.62, install $1,200, maintenance $75 a year; electric $0.16 a kWh, EF 0.95, install $900, maintenance $50 a year; 10 years.

1. Find the heat needed: 50 × 8.34 × 65 × 365 is 9,893,325 BTU a year, or 9.89 MMBtu.
2. Find the gas energy: 9,893,325 / 0.62 / 100,000 is 159.57 therms a year.
3. Find the gas cost: 159.57 × $1.50 is $239.35 a year.
4. Find the electric energy: 9,893,325 / 0.95 / 3,412 is 3,052.18 kWh a year.
5. Find the electric cost: 3,052.18 × $0.16 is $488.35 a year.
6. Find the energy saving: $488.35 − $239.35 is $248.99 a year.
7. Find the net saving: gas maintenance costs $25 a year more, so $248.99 − $25 is $223.99 a year.
8. Find the break-even year: one year of $223.99 is short of the $300 install gap; two years is $447.99, past it — so year 2.
9. Find the 10-year totals: $1,200 + 10 × $239.35 + 10 × $75 is $4,343.55 for gas, and $900 + 10 × $488.35 + 10 × $50 is $6,283.48 for electric.
10. Find the winner: $6,283.48 − $4,343.55 is $1,939.94 — gas wins.

Year by year: cumulative cost

Every branch, checked

• 50 gal/day, headline defaults: 50 gal/day, headline defaults: Gas $239.35/yr vs electric $488.35/yr, net saving $223.99/yr; gas wins by $1,939.94 over 10 years (break-even year 2). 50 gallons a day, headline defaults — gas wins by $1,939.94 over 10 years, breaking even in year 2.
• 80 gal/day: 80 gal/day: Gas $382.97/yr vs electric $781.36/yr, net saving $373.39/yr; gas wins by $3,433.90 over 10 years (break-even year 1). 80 gallons a day — a bigger household uses more hot water, so the saving grows with it and gas breaks even in year 1.
• Gas $2.00/therm: Gas $2.00/therm: Gas $319.14/yr vs electric $488.35/yr, net saving $144.21/yr; gas wins by $1,142.09 over 10 years (break-even year 3). Gas at $2.00 a therm — dearer gas shrinks the saving to $144.21 a year and pushes break-even to year 3.
• Electricity $0.10/kWh: Electricity $0.10/kWh: Gas $239.35/yr vs electric $305.22/yr, net saving $40.86/yr; gas wins by $108.63 over 10 years (break-even year 8). Electricity at $0.10 a kWh — cheap electricity nearly erases the gas advantage: gas wins by only $108.63, breaking even in year 8.
• Gas EF 0.55: Gas EF 0.55: Gas $269.82/yr vs electric $488.35/yr, net saving $193.53/yr; gas wins by $1,635.30 over 10 years (break-even year 2). Gas EF 0.55 — a less efficient gas heater burns more gas, so the saving falls to $193.53 a year.
• Electric EF 0.99: Electric EF 0.99: Gas $239.35/yr vs electric $468.62/yr, net saving $204.26/yr; gas wins by $1,742.62 over 10 years (break-even year 2). Electric EF 0.99 — a more efficient electric heater costs less to run, so the saving falls to $204.26 a year.
• Gas install $1,600: Gas install $1,600: Gas $239.35/yr vs electric $488.35/yr, net saving $223.99/yr; gas wins by $1,539.94 over 10 years (break-even year 4). Gas install $1,600 — a $700 install gap takes four years of saving to recover, so break-even moves to year 4.
• 20-year lifespan: 20-year lifespan: Gas $239.35/yr vs electric $488.35/yr, net saving $223.99/yr; gas wins by $4,179.87 over 20 years (break-even year 2). 20-year lifespan — ten more years of saving widen the lifetime gap to $4,179.87.
• Gas maintenance $150/yr: Gas maintenance $150/yr: Gas $239.35/yr vs electric $488.35/yr, net saving $148.99/yr; gas wins by $1,189.94 over 10 years (break-even year 3). Gas maintenance $150 a year — a $100 maintenance gap eats into the saving, leaving $148.99 a year net.
• 30 gal/day: 30 gal/day: Gas $143.61/yr vs electric $293.01/yr, net saving $124.40/yr; gas wins by $943.96 over 10 years (break-even year 3). 30 gallons a day — a small household saves less in absolute dollars, and break-even takes until year 3.

The reverses, worked backwards

• Smallest whole gal/day for gas to win over 10 years: 12 — at 12 the figures are Gas $57.45/yr vs electric $117.20/yr, net saving $34.76/yr; gas wins by $47.58 over 10 years (break-even year 9); at the lower neighbor the figures are Gas $52.66/yr vs electric $107.44/yr, net saving $29.78/yr; electric wins by $2.21 over 10 years (never breaks even within the lifespan); at the upper neighbor the figures are Gas $62.23/yr vs electric $126.97/yr, net saving $39.74/yr; gas wins by $97.38 over 10 years (break-even year 8) — verdict: STEP.
• Largest gas price (25¢ steps) for gas to still win: 2.50 — at 2.50 the figures are Gas $398.92/yr vs electric $488.35/yr, net saving $64.42/yr; gas wins by $344.24 over 10 years (break-even year 5); at the lower neighbor the figures are Gas $359.03/yr vs electric $488.35/yr, net saving $104.32/yr; gas wins by $743.16 over 10 years (break-even year 3); at the upper neighbor the figures are Gas $438.82/yr vs electric $488.35/yr, net saving $24.53/yr; electric wins by $54.69 over 10 years (never breaks even within the lifespan) — verdict: STEP.
• Smallest whole gal/day for a net saving of $100/yr or more: 26 — at 26 the figures are Gas $124.46/yr vs electric $253.94/yr, net saving $104.48/yr; gas wins by $744.77 over 10 years (break-even year 3); at the lower neighbor the figures are Gas $119.68/yr vs electric $244.17/yr, net saving $99.50/yr; gas wins by $694.97 over 10 years (break-even year 4); at the upper neighbor the figures are Gas $129.25/yr vs electric $263.71/yr, net saving $109.46/yr; gas wins by $794.57 over 10 years (break-even year 3) — verdict: STEP.
• Smallest electricity rate (1¢ steps) for gas to still win: 0.10 — at 0.10 the figures are Gas $239.35/yr vs electric $305.22/yr, net saving $40.86/yr; gas wins by $108.63 over 10 years (break-even year 8); at the lower neighbor the figures are Gas $239.35/yr vs electric $274.70/yr, net saving $10.34/yr; electric wins by $196.59 over 10 years (never breaks even within the lifespan); at the upper neighbor the figures are Gas $239.35/yr vs electric $335.74/yr, net saving $71.38/yr; gas wins by $413.85 over 10 years (break-even year 5) — verdict: STEP.
• Smallest whole lifespan for gas to win: 2 — at 2 the figures are Gas $239.35/yr vs electric $488.35/yr, net saving $223.99/yr; gas wins by $147.99 over 2 years (break-even year 2); at the lower neighbor the figures are Gas $239.35/yr vs electric $488.35/yr, net saving $223.99/yr; electric wins by $76.01 over 1 year (never breaks even within the lifespan); at the upper neighbor the figures are Gas $239.35/yr vs electric $488.35/yr, net saving $223.99/yr; gas wins by $371.98 over 3 years (break-even year 2) — verdict: STEP.
• Largest gas install ($100 steps) for gas to still win: 3100 — at 3100 the figures are Gas $239.35/yr vs electric $488.35/yr, net saving $223.99/yr; gas wins by $39.94 over 10 years (break-even year 10); at the lower neighbor the figures are Gas $239.35/yr vs electric $488.35/yr, net saving $223.99/yr; gas wins by $139.94 over 10 years (break-even year 10); at the upper neighbor the figures are Gas $239.35/yr vs electric $488.35/yr, net saving $223.99/yr; electric wins by $60.06 over 10 years (never breaks even within the lifespan) — verdict: STEP.

What the defaults assume

The defaults are 50 gallons of hot water a day, a $1,200 gas heater at EF 0.62 against a $900 electric heater at EF 0.95, $1.50 a therm, $0.16 a kWh, and a 10-year lifespan. They are a starting point, not a quote: your household may use more or less water, your fuel prices will differ, and the right answer for you is the one your numbers describe. The 55 °F inlet and 120 °F set point are typical US averages — colder inlet water or a hotter set point raises both bills. Standby losses are inside the EF ratings, no rebates or tax credits are modelled, and tankless systems are a different comparison — see the tank-vs-tankless-water-heater guide. Put your numbers in, read the answer, and check the working before you use it.

These notes repeat in every explainer section because this page is built to be read start to finish: the inlet and set temperatures are typical averages; EF ratings are lab figures; and the install gap decides the break-even year.

Output · formula · meaning

Who uses this

• A homeowner replacing a dead water heater — $300 more to install, $223.99 a year back, break-even in year 2, $1,939.94 ahead over 10 years.
• A homeowner with both fuels available weighing a gas line against an electric swap — the install gap is the number that decides it.
• A landlord fitting out a rental — the year-by-year table shows exactly when the dearer heater starts paying for itself.
• A buyer comparing quotes — two install prices, two EFs and two fuel prices, and the lifetime gap follows from them.

Accuracy & limitations

The arithmetic is exact on the numbers you type: 50 gallons a day at a 65 °F rise is 9,893,325 BTU a year, and 159.57 therms at $1.50 is $239.35. What the calculator cannot do is measure your home: EF ratings are lab figures, so real efficiency depends on usage pattern, insulation and climate. The 55 °F inlet and 120 °F set point are typical US averages — colder inlet water or a hotter set point raises both bills. Standby losses are inside the EF ratings, no rebates or tax credits are modelled, and tankless systems are a different comparison. Fuel prices are held flat — if gas gets dearer or electricity gets cheaper, the gap narrows; if the reverse, it widens. Treat the answer as a comparison of two quotes, not a quote itself.

Cite this calculator

On 50 gallons a day, gas costs $239.35 a year against $488.35 for electric — a net saving of $223.99 a year after maintenance — and over 10 years gas wins by $1,939.94: the gas heater catches up in year 2. Smallest whole gal/day for gas to win over 10 years: 12. Largest gas price (25¢ steps) for gas to still win: 2.50. Smallest whole gal/day for a net saving of $100/yr or more: 26. Smallest electricity rate (1¢ steps) for gas to still win: 0.10. Smallest whole lifespan for gas to win: 2. Largest gas install ($100 steps) for gas to still win: 3100. Source: Bright Side Kit, brightoolbox.com.

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