Tankless Water Heater Cost: $1,406 to $3,902 by Size (2026)

National prices. The installed figures include the unit and labor; retrofit work (gas line, venting, a new circuit) is covered on the tankless installation page.

What to do right now if your water heater just failed

If the old tank failed today, deal with the water first and decide on tankless second. A tank-to-tankless upgrade takes half to a full day of labor (HomeGuide) and may need a bigger gas line, a vent or a circuit, so it is rarely a same-day swap.

1. Smell gas? Leave first. Peoples Gas says not to try to find or stop the leak; call 911 and the gas utility from outside.
2. Water near outlets or cords? Stay out of it. The Red Cross warns not to touch electrical equipment if it is wet or if you are standing in water.
3. Leaking tank: shut off the water to the heater. Rheem's manual says that if a water heater has been through flood, fire or physical damage, turn off its power and water.
4. Water on floors or walls? Take photos before you clean up (FEMA), then call your insurer. The Texas Department of Insurance says most policies cover sudden water damage but not gradual leaks. Do not sign your claim over to a contractor; Florida bans assignment of benefits on policies issued on or after January 1, 2023.
5. Ask for two prices: a like-for-like tank and a tankless unit. HomeAdvisor's average tank replacement is $1,348; tankless averages $2,641.

Is it an emergency? A leaking tank vs a planned upgrade

A water heater is an emergency when the tank is leaking from its body, water is spreading, or you smell gas; switching to tankless is a planned job. Rheem says water pooling at a tank's body suggests internal corrosion that usually means replacement, and HomeGuide puts a leaking tank replacement at $600 to $1,800.

• Call today: the tank is leaking, water is near the electrical panel or outlets, or there is a gas smell (leave first).
• Plan it: an old tank that still works, rising bills, or running out of hot water. That is the right time to price tankless, with a gas line and vent check.
• After-hours cost: HomeAdvisor puts night, weekend and holiday surcharges at $100 to $300 or more. See water heater repair for problems you can fix without replacing anything.

How much is a tankless water heater by size (GPM)?

A tankless water heater's price climbs with its flow rate: Angi's 2026 table runs from $150 to $250 for a 1 to 2 GPM unit to $600 to $2,000 for one over 8 GPM. Angi says an average home needs 5.5 to 7.5 GPM.

Angi's price table by size; Angi lists installation labor separately at $600 to $1,850. The typical-use column applies the DOE, HomeAdvisor and HomeGuide flow figures in the sizing section below.

Gas vs electric tankless water heater cost

Gas tankless units cost more up front and deliver more hot water; electric units cost less but deliver less. The DOE says a 70 F temperature rise is typically possible at 5 gallons a minute through a gas-fired unit and 2 gallons a minute through an electric one. HomeAdvisor says electric models top out around 8 GPM and gas models reach 20.

Angi's price table for electric tankless units by power rating.

• Electric needs power. HomeAdvisor says a whole-house electric unit needs 240V, 80 amp hard-wired service at a minimum and a home with at least 150 amp service. HomeGuide puts a dedicated circuit at $250 to $900 and a panel replacement at $850 to $1,700; see electrical panel upgrade.
• Gas needs a vent and enough gas. HomeGuide puts first-time venting at $500 to $1,500 and a larger gas supply line at $350 to $2,000; Angi says gas line work can run up to $1,000.
• Running cost. HomeGuide puts yearly operating cost at $220 to $480 for gas and $340 to $540 for electric. HomeAdvisor says about $200 a year for natural gas and $350 for propane.

The full retrofit picture, including permits and who does each part, is on tankless water heater installation.

What size tankless water heater do I need?

You need a tankless water heater rated for the hot water you use at the same time, at the temperature rise your incoming water needs. The DOE's method: list the fixtures you expect to run at once, add their flow rates, then subtract the incoming water temperature from the temperature you want. The DOE says to assume 50 F incoming water unless you know otherwise, and that most uses need 120 F, a 70 F rise.

Step 1: add up the flow rates

DOE Energy Saver: Sizing a New Water Heater; HomeAdvisor tankless guide (June 2026).

The DOE's own example: a hot water faucet at 0.75 GPM plus a shower at 2.5 GPM needs a heater that delivers 3.25 GPM at a 70 F rise. HomeAdvisor says to count each shower separately and to avoid oversizing, since a higher GPM costs more.

Step 2: check the temperature rise

The colder your incoming water, the more GPM you lose. HomeGuide's example: 60 F groundwater heated to 115 F is a 55 F rise. A unit rated 5 GPM in a warm climate delivers less in a cold one, so ask the installer for the unit's flow at your local rise, not just its maximum.

Quick sizing by household

HomeGuide water heater installation guide (January 2026).

Tankless vs tank water heater: cost over time

A tankless water heater costs close to twice as much as a tank to install (Fixr) but lasts about 20 years against 10 to 15 for a tank, and is 8% to 34% more efficient, according to the DOE. HomeAdvisor's 2026 average for a tank replacement is $1,348, against $2,641 for tankless.

• Savings: Angi, citing the DOE, puts yearly savings at about $100 for gas and $50 for electric.
• Upkeep: HomeGuide puts a tankless flush at $150 to $350 and says to flush at least once a year; Rheem says whistling or hissing from a tankless unit points to scale.
• Repairs: HomeGuide puts tankless repairs at $300 to $1,300.
• Tax credit: the IRS says the federal 25C credit does not apply to property placed in service after December 31, 2025. Some gas utilities still offer tankless rebates in 2026; check yours before you buy.

Are tankless water heaters worth it?

A tankless water heater is worth it when the house already has gas and a good vent route, you plan to stay long enough to use its 20-year life, and running out of hot water is a regular problem. It is a weaker buy when the retrofit needs a new gas line or a panel upgrade, or when the tank failed today and you need hot water tonight; a like-for-like tank is covered in water heater replacement cost.

Where to buy a tankless water heater, and who installs it

You can buy the unit from a retailer or through the installer, and Angi says buying through a plumbing company can cost up to 30% more than from a major retailer. The trade-off is warranty and sizing responsibility, so ask the plumber whether they will install a unit you supply and what warranty covers it. HomeAdvisor's brand price ranges run from $150 to $1,600 for EcoSmart to $900 to $3,000 for Takagi, with Rheem at $300 to $1,500 and Rinnai at $500 to $2,300.

1. What GPM will this unit deliver at my incoming water temperature?
2. Does my gas line, vent or electrical panel need work, and what does it cost?
3. Is removal of the old tank included?
4. How often does it need descaling, and do you offer it?
5. What is your license number, and who pulls the permit?

City guides include water heater repair in Denver, Phoenix and Houston. General plumber rates are on plumber cost, and every trade's prices on home repair costs. Calls go to an independent company that serves your area and takes water heater work. How calls work.