Tankless vs Tank Water Heater Cost Calculator - 2026 Break-Even

See whether a tankless or a standard tank gas water heater is actually cheaper over time - weigh the higher tankless install against its lower yearly running cost and find your break-even year.

Tank wins

$328 cheaper

Tankless

$6,742

Tank

$6,414

Break-even

Year 19

Usage

Hot water use

gal/day

20 gal/day120 gal/day

Time horizon

5 yr25 yr

Energy Rate

Gas rate

$/therm

0.5 $/therm4 $/therm

Up-front Cost (installed)

Tankless unit

1500 $5000 $

Tank unit

600 $2500 $

Tank wins

Saves $328 over 15 years · breaks even in year 19

Tankless

$6,742

Up-front$3,000

Per year$249

Best

Tank

$6,414

Up-front$1,300

Per year$341

Total cost over 15 years

Tankless$6,742

Tank$6,414

Cumulative cost over time

Cumulative cost over time — crossover at year 19

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JACO ThreadPro High-Density Thread Seal Tape - 1/2" x 125 ft. (Mega Roll) | Professional PTFE Pipe Sealant | Plumbers Tape

$7.904.7

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SharkBite 3/4 Inch And 1 Inch ContracTor Kit, Push To Connect Fitting, 22795LF

$22.524.6

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Dixon Valve TTB75 PTFE Industrial Sealant Tape, -212 to 500 Degree F Temperature Range, 3.5mil Thick, 520" Length, 3/4" Width, White

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Example Calculations

1Average use, average gas rate (default)

Inputs

Hot water use64 gal/day

Time horizon15 years

Gas rate$1.50/therm

Installed costTankless $3,000 / Tank $1,300

Result

Cheaper optionTank - saves $328 over 15 yrs

Tankless 15-year total$6,742

Tank 15-year total$6,414

Break-even~Year 19 (beyond horizon)

Heat delivered is 64 x 365 x 8.34 x 70 = 13,637,568 BTU/year. Tankless burns 166 therms (~$249/yr); tank burns 227 therms (~$341/yr) - a real $92/year saving. But the $1,700 higher install takes ~18.6 years to recover, so over a 15-year window the cheaper tank wins by ~$328.

2High gas rate ($3.00/therm)

Inputs

Hot water use64 gal/day

Time horizon15 years

Gas rate$3.00/therm

Installed costTankless $3,000 / Tank $1,300

Result

Cheaper optionTankless - saves $1,044 over 15 yrs

Tankless 15-year total$10,484

Tank 15-year total$11,528

Break-evenYear 10

At $3.00/therm tankless runs ~$499/year vs tank ~$682/year. Expensive gas magnifies the 0.82 vs 0.60 EF gap to ~$183/year, cutting break-even to ~10 years and saving ~$1,044 over the 15-year horizon.

3Big family, 100 gal/day

Inputs

Hot water use100 gal/day

Time horizon15 years

Gas rate$1.50/therm

Installed costTankless $3,000 / Tank $1,300

Result

Cheaper optionTankless - saves $444 over 15 yrs

Tankless 15-year total$8,847

Tank 15-year total$9,291

Break-evenYear 12

A big household using 100 gal/day burns ~260 therms on tankless vs ~355 on a tank. More hot water means the EF gap saves ~$143/year ($390 vs $533), so break-even falls to ~12 years and tankless saves ~$444 over 15 years.

Show all examples

Did You Know?

For a typical home using 64 gallons of hot water a day in 2026, a tankless gas water heater (0.82 EF) costs about $249/year to run, versus about $341/year for a standard tank (0.60 EF) at $1.50/therm - a real $92/year saving from skipping standby losses. But tankless installs run about $3,000 versus $1,300 for a tank, a $1,700 premium that takes roughly 19 years to pay back. Over a 15-year horizon the tank actually wins by about $328 ($6,414 vs $6,742). Tankless only pulls ahead when you use a lot of hot water or gas is pricey: at $3.00/therm or 100 gallons a day, break-even drops to about 10-12 years. The honest verdict: buy tankless for endless hot water and a ~20-year lifespan, not to save money fast.

Frequently Asked Questions

Is a tankless water heater cheaper than a tank?

Not usually on cost alone, at least not for a long time. A tankless gas unit converts about 0.82 of its gas into hot water versus roughly 0.60 for a standard storage tank, which loses heat standing by. For a typical home using 64 gallons a day, that efficiency edge saves about $92 a year - $249 versus $341 at $1.50/therm. But tankless costs about $1,700 more to install ($3,000 vs $1,300), so the simple break-even is around 19 years. Over a 15-year horizon the cheaper-to-install tank actually wins by about $328. Tankless turns the corner only when you use lots of hot water or gas is expensive.

Tankless running cost: ~$249/year (0.82 EF, 64 gal/day, $1.50/therm)
Tank running cost: ~$341/year (0.60 EF) - about $92/year more
Tankless installs ~$1,700 higher ($3,000 vs $1,300)
Break-even: ~19 years - longer than most buyers expect
Over 15 years the tank is ~$328 cheaper at average usage

System	Installed	Running / year	15-Year Total
Tankless (0.82 EF)	$3,000	~$249	~$6,742
Tank (0.60 EF)	$1,300	~$341	~$6,414
Tankless @ $3.00/therm	$3,000	~$499	~$10,484

Why is the tankless payback so long?

Because the dollar saving from efficiency is small next to the up-front gap. The EF jump from 0.60 to 0.82 only trims about $92 a year at typical usage and a $1.50/therm gas rate, while a tankless unit costs roughly $1,700 more to install than a tank. Divide $1,700 by $92 and you get about 18.6 years to break even. Standby losses on a tank are real, but in dollars they are modest unless gas is expensive. The payback shortens fast with more hot water use or a higher gas rate, and a tankless unit usually outlives the tank it replaced.

Yearly saving at default use: only ~$92
Install premium: ~$1,700 ($3,000 vs $1,300)
Payback = $1,700 / $92 = about 18.6 years
Standby losses cost real money only when gas is pricey
Tankless lasts ~20 years and can outlive its own payback

When does a tankless water heater actually save money?

When you use a lot of hot water or gas is expensive - both scale up the efficiency saving. Raise the gas rate to $3.00/therm and break-even falls to about 10 years, with tankless saving roughly $1,044 over 15 years. Push usage to 100 gallons a day and break-even drops to about 12 years and a $444 saving. Big families, high gas rates, and long ownership all tip the math toward tankless. There are non-cost reasons too: endless hot water that never runs out mid-shower, and 12 to 16 square feet of reclaimed floor space.

At $3.00/therm: break-even ~10 years, saves ~$1,044 over 15 yrs
At 100 gal/day: break-even ~12 years, saves ~$444 over 15 yrs
Higher gas rate amplifies the 0.82 vs 0.60 EF gap
More hot water = more therms = bigger absolute savings
Bonus: endless hot water and reclaimed floor space

How long do tankless vs tank water heaters last?

A tankless gas unit typically lasts about 20 years, nearly double a storage tank at roughly 10 to 12 years. That lifespan gap changes the lifetime math: even with a ~19-year cost break-even, a tankless that outlives a second tank replacement can come out ahead on total cost of ownership. Storage tanks usually fail when the steel tank corrodes and leaks, which ends their life outright; tankless units have replaceable heat exchangers and parts. Annual descaling - especially with hard water - keeps a tankless near its rated 0.82 EF instead of fouling and losing efficiency.

Tankless lifespan: ~20 years
Tank lifespan: ~10-12 years
You may buy two tanks within one tankless lifetime
Tanks fail by corrosion; tankless parts are replaceable
Annual descaling holds tankless near 0.82 EF in hard water

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Last Updated: Jun 16, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

Tankless vs Tank Water Heater Cost Calculator - 2026 Break-Even

Usage

Energy Rate