Quick Answer: A tankless water heater costs $1,400 to $5,600 installed in 2026, with the typical complete project running about $2,632 per HomeGuide’s 2026 cost data. The unit itself is only 40–45% of the total — whole-home electric heaters run $230–$850 and gas condensing units $1,199–$1,799, with the remaining $800–$3,000 going to labor, permits, venting, and gas or electrical upgrades. Electric installs land at $1,400–$3,000, gas at $2,100–$5,600. The big 2026 change: the federal 25C tax credit that paid up to $600 for a qualifying gas tankless unit expired for anything placed in service after December 31, 2025, so a 2026 install gets no federal help at all.
Tankless pricing confuses buyers because two very different numbers get called “the cost.” The sticker on the box is one thing; the plumber’s quote is often three times that. This guide separates them — what each class of unit actually costs, what the install adds and why, which upgrades quietly double a quote, and how the payback math looks now that the federal credit is gone.
The 2026 headline numbers
| Cost component | Electric | Gas (condensing) | Notes |
|---|---|---|---|
| Unit only | $230–$850 | $1,057–$1,799 | Whole-home models; point-of-use units start ~$130 |
| Labor | $600–$1,500 | $1,000–$2,500 | 3–10 hours of plumber and/or electrician time |
| Venting | $0 | $300–$1,000 | Electric units need no venting at all |
| Gas line upsize | — | $500–$1,500 | Often needed to feed 160,000–199,000 BTU |
| Panel / service upgrade | $1,500–$4,000 | — | Only if your panel can't carry ~100–150A |
| Permit | $50–$500 | $50–$500 | Varies widely by municipality |
| Typical installed total | $1,400–$3,000 | $2,100–$5,600 | Median across both: ~$2,632 |
By the numbers
- $1,400 to $5,600 installed, with a typical project near $2,632 — the full 2026 range across fuel types, where the unit is only 40–45% of the total and labor, permits, and modifications add another $800–$3,000. — HomeGuide 2026 tankless cost data
- 24%–34% more energy efficient than a storage tank for homes using 41 gallons or less of hot water daily, falling to 8%–14% for high-use homes near 86 gallons a day — the single most important number in any payback calculation, and the reason low-use households benefit most. — U.S. Department of Energy
- The 25C federal credit of up to $600 expired for equipment placed in service after December 31, 2025, repealed by the One Big Beautiful Bill Act. High-efficiency gas tankless units with a UEF of 0.95+ qualified through December 2025 only; there is no federal replacement for 2026. — ENERGY STAR / Rewiring America
- 15–20 year service life versus 8–12 years for a storage tank — roughly double, which is where most of tankless’s lifetime economics actually come from. — HomeGuide
What the unit itself costs
Unit price splits hard along fuel type, and it’s the cleanest place to control your budget.
Electric whole-home ($230–$850). These are the value play. A Rheem RETEX-24 is $549 at Home Depot, an EcoSmart ECO 27 about $500 with a limited lifetime warranty on registration, and a Stiebel Eltron Tempra 24 Plus around $650 for the German-built premium option with Advanced Flow Control. Small units go lower — an EcoSmart ECO 11 is roughly $230, a Rheem RTEX-13 about $255. Cold-climate 36 kW flagships top out near $850.
Rheem RETEX-24 (24 kW Electric)
- The cheapest credible route to whole-home tankless: a mainstream-brand 24 kW unit at roughly half the price of an entry gas condensing heater.
- No venting, no gas line, no condensate drain — the three line items that push gas quotes past $3,000 simply don't exist on this job.
- The catch is amperage: ~100A of dedicated service. If your panel already has room, this is the lowest-total-cost path to tankless.
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Gas condensing ($1,057–$1,799). You pay more for the box and more to install it, but you get whole-home flow in any climate. Rheem’s Performance Plus ECO200DVELN-3 is $1,057.39 (non-condensing), the Performance Platinum ECOH200DVELN-3 is $1,199 at 9.5 GPM and 0.93 UEF, the Rinnai Sensei RX199iN runs $1,530–$1,725 street with a 0.98 UEF and a 15-year heat exchanger warranty, and Rheem’s IKONIC ECOHS200iN lists at $1,799 — recently $1,439 on sale at Home Depot.
Point-of-use ($130–$290). A single remote sink doesn’t need a whole-home unit. An EcoSmart POU 3.5 is about $130 and a Stiebel Mini 3-1 about $220, both on a standard circuit — a genuine DIY afternoon.
Where the install money actually goes
This is the part quotes hide. Labor alone runs $600 to $2,500 for 3 to 10 hours of plumber and electrician time, but the swing factor is what your house needs on top.
- Gas line upsizing ($500–$1,500). A whole-home gas tankless fires at 160,000–199,000 BTU. Most homes were plumbed for a 40,000 BTU tank on a 1/2-inch line. Feeding the new unit often means running 3/4-inch pipe back toward the meter — sometimes the meter too. This is the single most common gas-quote surprise.
- Venting ($300–$1,000). Condensing units run cool exhaust through PVC or dedicated stainless. If you’re relocating the heater to an exterior wall it’s cheap; if it stays in a basement interior, less so.
- Electrical panel upgrade ($1,500–$4,000). The electric equivalent trap. A 24 kW unit wants ~100A of dedicated service and a 36 kW unit ~150A. On a 100A or 150A total panel, that’s a service upgrade — and it can cost more than the heater. Get an electrician’s load calculation before you buy the unit, not after.
- Isolation valves ($60–$150). Optional at install, near-mandatory in practice. Without them, annual descaling is a much bigger job. Add them up front.
- Permits ($50–$500) and condensate drain. Both usually minor, both usually forgotten in DIY budgets.
The pattern worth internalizing: the cheapest tankless installs are like-for-like electric swaps with existing panel capacity; the most expensive are gas conversions that need a new line, new venting, and a relocation. Same product category, four-times price difference, decided almost entirely by your house rather than your heater.
The tax credit is gone — what that changes
Through December 2025, a qualifying gas tankless unit with a UEF of 0.95 or higher earned up to $600 back under Section 25C. The One Big Beautiful Bill Act repealed it, and the credit expired for any equipment placed in service after December 31, 2025. Heat pump water heaters lost their much larger 25C credit on the same date.
Two practical consequences for 2026 buyers:
- If your unit was installed and operational on or before December 31, 2025, you can still claim it on your 2025 return — and you can amend up to three years back if you missed a qualifying earlier install.
- If you’re installing in 2026, budget the full sticker. The federal offset is zero. Check your gas or electric utility’s rebate program and your state energy office instead — utility rebates are now the only meaningful incentive, and they vary from nothing to several hundred dollars.
Losing $600 pushes the break-even on a premium gas unit out by roughly four to eight years of energy savings. It doesn’t change whether tankless makes sense — but it does strengthen the case for a $549 electric unit over a $1,799 gas flagship in homes where either would work.
Does it pay back?
Honestly: on energy alone, slowly. The DOE’s 24%–34% efficiency advantage applies to homes using 41 gallons or less of hot water daily, and drops to 8%–14% for heavy users near 86 gallons. On a typical household’s water heating bill, that’s about $75–$150 a year — against a $1,000–$2,000 premium over a comparable tank, a straight energy payback of 8 to 15 years.
The better argument is lifespan. A tankless unit lasts 15–20 years against 8–12 for a storage tank. Buy tankless once and you skip a full tank replacement cycle — and that avoided $1,500–$2,500 replacement, plus never running out of hot water and reclaiming the closet floor space, is where the decision actually lands. If you’re weighing the two, our tankless vs tank comparison runs the full trade-off, and electric vs gas covers the fuel choice that drives most of the cost spread above.
How to keep your quote down
- Stay in the same fuel and the same location. Every relocation, every fuel conversion, adds four figures. A like-for-like swap is the cheapest tankless job there is.
- Get the load calculation before the heater. For electric, an electrician’s panel check costs a fraction of discovering mid-install that you need a service upgrade.
- Get three quotes, itemized. Ask each to break out unit, labor, venting, gas line, and permit separately. The spread between plumbers on the same job routinely exceeds $1,000, and itemization is how you see why.
- Right-size instead of over-buying. A 36 kW unit in a warm climate is money spent on kilowatts you’ll never use — and it drags the electrical upgrade along with it. Size to your coldest-month inlet temperature and your real simultaneous-fixture demand.
- Include isolation valves and plan the annual flush. $60–$150 now saves a much larger descaling bill every year for two decades, and protects the warranty.
The bottom line
Budget $1,400–$3,000 for electric and $2,100–$5,600 for gas, with a realistic middle-of-the-road project at about $2,632. The unit is the small half of that — $500–$850 buys a strong whole-home electric heater, $1,199–$1,799 a gas condensing flagship — and your house decides the rest through gas line, venting, and panel work. With the federal 25C credit dead as of January 1, 2026, there’s no longer a $600 federal cushion, which makes the value-electric path more compelling than it was a year ago for any home that can carry the amperage. Start with our best tankless water heater picks for the shortlist, or go straight to the best electric tankless roundup if the numbers above pointed you that way.