Tankless water heater installation cost: electric and gas, by size, by state
A gas tankless heater, 4 to 4.9 gallons a minute: about $1,950 to $2,600, typically $2,250. That's a new tankless water heater set and connected with the old heater taken out, plus the contractor's overhead, profit and sales tax. A bigger gas line, a new vent, an electrical service upgrade for an electric heater, and permits are extra.
Anthony Hicks30+ years in construction. Updated November 5, 2026.
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What it costs
| Job | Cost |
|---|---|
| An electric tankless heater, 15 to 20 kW | $1,750 to $2,350 |
| A gas tankless heater, 4 to 4.9 gallons a minute | $1,950 to $2,600 |
| A gas power-vent tankless heater, 5 to 5.9 gallons a minute | $2,950 to $3,550 |
Totals include the contractor's overhead and profit (20%) and the state's average sales tax. Prices as of November 2026.
What’s in these numbers
Each total is a typical job, priced the way a contractor’s estimate is priced:
| Electric | Gas | Gas, larger | |
|---|---|---|---|
| Heater | 15 to 20 kW electric | Gas, about 4 to 4.9 gallons a minute | Gas power-vent, about 5 to 5.9 gallons a minute |
| Old heater | Taken out | Taken out | Taken out |
On top of the work:
- Overhead and profit: 20%, the standard markup on a contractor’s estimate.
- Sales tax on the materials, at the state’s average rate.
Not in them: a larger gas line, a new or different vent, a new circuit or an electrical service upgrade for an electric heater, moving the heater, a water softener or filter, and permits.
Gallons a minute, not gallons
A tankless heater has no tank to run out: it heats the water as it flows. It’s sized by how many gallons a minute it can heat by the temperature rise you need, so the same heater gives less hot water in winter, when the incoming water is colder. A tank’s size is its gallons and its first hour rating; the water heater installation cost guide prices 40 and 50 gallon tanks side by side.
What moves the price
- Gas or electric. A gas tankless heater needs its gas line and vent sized to its instructions; an electric one can need a large dedicated circuit, and the electrical panel upgrade guide covers a bigger service.
- Switching from a tank. The tank’s gas line, vent and wiring were sized for a tank; changing them is extra work on top of these numbers.
- Flow. Heaters rated for more gallons a minute cost more.
- Where you live. Pick your state in the box above.
Common questions
How much does a tankless water heater cost installed?
About $1,950 to $2,600 for a gas tankless heater with the old heater taken out, typically $2,250.
How much is an electric tankless water heater installed?
About $1,750 to $2,350 for a 15 to 20 kW heater where the wiring already suits it.
How much for a larger gas tankless heater?
About $2,950 to $3,550 for a power-vent heater of about 5 to 5.9 gallons a minute, typically $3,200.
The old tank leaked. What else is there?
The water heater leak guide covers finding where it’s coming from, and the water damage restoration guide the drying out.