If your old water heater is leaking, running out of hot water, or simply getting old, a tankless (on-demand) water heater is probably on your list. The first question every homeowner asks is the same: how much will it cost?
In 2026, most US homeowners pay between $1,400 and $4,500 in total to buy and install a tankless water heater, with a typical whole-home gas installation landing around $2,800 to $3,200. Electric point-of-use units cost far less, while high-end condensing gas systems with new venting and gas-line work can pass $5,500. This guide breaks down exactly where that money goes, so you can budget with no surprises.
Tankless Water Heater Cost at a Glance
| Type | Unit Price | Total Installed Cost |
|---|---|---|
| Electric tankless (point of use) | $150 – $600 | $500 – $1,200 |
| Electric tankless (whole home) | $500 – $1,200 | $900 – $2,500 |
| Gas tankless (non-condensing) | $700 – $1,800 | $2,200 – $4,200 |
| Gas tankless (condensing, high efficiency) | $1,200 – $2,500 | $3,000 – $5,800 |
These are national averages for 2026. Your real quote depends on your home’s plumbing, gas and electrical setup, and local labor rates — the factors below explain most of the difference between a $1,400 job and a $5,000 job.
What Affects the Cost?
- Fuel type: Gas models cost more to buy and install than electric ones, mainly because of venting and gas-line work — but gas usually costs less to run.
- Size (flow rate): Tankless heaters are sized in gallons per minute (GPM). A small home may need only 5–6 GPM; a large family home running two showers and a washing machine at once may need 9–11 GPM, which means a bigger, pricier unit.
- Venting: Gas units need safe exhaust venting. If your old tank heater vented through a chimney, new stainless or PVC venting can add $300 – $1,000.
- Gas line upgrade: Many homes need a larger gas line for a tankless unit’s higher BTU demand. Expect $250 – $800 if this applies to you.
- Electrical work: Whole-home electric models draw a lot of power and may need new circuits ($300 – $900) or even a panel upgrade ($1,000 – $2,500).
- Permits and labor: Permits typically run $100 – $400, and professional installation labor ranges from about $500 to $1,800 depending on complexity and your state.
Tankless vs. Tank Water Heater: Is It Worth It?
A traditional tank water heater costs much less upfront — usually $1,300 to $2,500 installed — but it keeps 40–50 gallons of water hot all day, wasting energy. A tankless unit heats water only when you open a tap. According to the U.S. Department of Energy, homes that use less than 41 gallons of hot water a day can save roughly 24%–34% on water-heating energy with a tankless model.
Tankless units also last longer: around 20 years or more, versus 8–12 years for a tank. Over that lifespan, the higher upfront cost is often recovered through energy savings and one avoided replacement — but if you plan to move within a few years, a standard tank may be the smarter buy.
Running Costs
A gas tankless water heater typically costs about $180 – $260 per year to run for an average household, while an electric tankless model runs roughly $300 – $420 per year depending on local electricity prices. Actual bills depend heavily on how much hot water your family uses.
Should You Install It Yourself?
Installing a small electric point-of-use unit under a sink is a realistic DIY project for an experienced homeowner. Whole-home systems — especially gas — are a different story: gas lines, venting, permits and warranty conditions make professional installation the safe and usually required choice. Most manufacturers also require licensed installation to keep the warranty valid.
How to Save Money on a Tankless Water Heater
- Get at least three written quotes — prices for the same job can differ by $1,000 or more between companies.
- Right-size the unit: an oversized heater costs more to buy and install, with no benefit.
- Check rebates and tax credits: qualifying high-efficiency models may be eligible for a federal energy tax credit (30% of cost, up to $600) and many states and utilities offer additional rebates of $100 – $1,000. Check current availability before you buy, as programs change.
- Replace before it fails: an emergency replacement removes your time to compare quotes — planning ahead is the cheapest upgrade of all.
Frequently Asked Questions
How much does it cost to replace a tank water heater with a tankless one?
Switching from a tank to a tankless system usually costs $2,500 – $5,500 in total, because the job often includes new venting plus gas or electrical changes on top of the unit and labor.
How long does installation take?
A straightforward replacement takes a licensed plumber about 4–8 hours. Jobs needing new gas lines, venting or electrical work can take 1–2 days.
What size tankless water heater do I need?
Add up the flow rates of everything that might run at once: a shower uses about 2 GPM, a washing machine about 2 GPM, and a dishwasher about 1.5 GPM. Most family homes need 7–10 GPM in warm climates and more in cold northern states, where incoming water is colder.
Do tankless water heaters need maintenance?
Yes — descaling (flushing with vinegar or a descaling solution) once a year, especially in hard-water areas. A professional service visit costs about $150 – $250, and skipping it shortens the unit’s life.
Is a tankless water heater worth it for a small home?
Often yes. Low hot-water usage is exactly where tankless savings are highest, and a compact unit frees up the space a bulky tank used to occupy.
A tankless water heater is a bigger investment upfront, but for the right home it pays back through lower energy bills, endless hot water and a much longer lifespan. Use the ranges above to sanity-check any quote you receive — and remember that all figures on CostlyUSA are researched national averages; your final price always depends on your home and your local market. Read our Disclaimer (/disclaimer/) for how our estimates work.