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Cost guide

Tankless Water Heater Conversion Cost

Converting from a tank water heater to a tankless gas or electric unit, including venting, gas line, or electrical upgrades.

Typical range
$3,500–$9,000
Most people pay
$5,500
Service life
15–20 years for tankless units versus 8–12 for tanks

National cost range

National range, per conversion installed

$3,500 – $9,000

Most homeowners pay around $5,500. The spread is real, not hedging — the drivers below determine which end of it you land on.

Low end
$3,500
Simple access, like-for-like
Typical
$5,500
What most jobs come in at
High end
$9,000
Upgrades, difficult access, code work

What you are actually paying for

Find the row that matches your situation. Quotes that differ wildly from each other usually differ in scope, not in price.

ScenarioTypical cost
Gas tankless, gas line adequate, exterior ventBest-case conversion when infrastructure is ready.$3,500–$5,500
Gas tankless plus gas line upsizeGas line work is the most common added cost.$4,500–$7,000
Gas tankless plus new venting and gas lineFull infrastructure upgrade for the conversion.$5,500–$9,000
Electric tankless, panel has capacityRequires dedicated 240V circuit; feasible when panel space exists.$2,500–$4,500
Electric tankless plus panel upgradeWhole-house electric tankless often needs 120+ amps of new capacity.$5,000–$9,000

What moves the price

In descending order of impact. These are also the questions worth asking a contractor whose quote sits outside the range above.

  1. Gas line upsizing

    A tankless gas unit may need 3/4-inch gas line where the old tank used 1/2 inch. Running new gas pipe is the most common hidden cost on a conversion quote.

  2. Venting change

    Tankless gas units require category III or IV stainless venting through the wall or roof. Abandoning the old atmospheric vent and installing new vent pipe adds $500 to $1,500.

  3. Electrical for electric tankless

    A whole-house electric tankless may need 120 to 160 amps of dedicated capacity — often requiring a panel upgrade. Point-of-use electric units are simpler.

  4. Water treatment

    Tankless manufacturers often require water hardness below 11 gpg. A softener installed concurrently adds $800 to $2,000.

  5. Unit capacity and brand

    A 6.5 GPM unit handles one bathroom. An 8 to 10 GPM unit handles a whole house. Navien, Rinnai, and Rheem are the common brands; capacity drives price.

Can you do it yourself?

Not a DIY job

Tankless conversion involves gas piping, combustion venting, or high-amperage electrical work. All require licensed professionals and permits. This is not a DIY project.

Permits and inspection

Plumbing, gas, and electrical permits may all be required depending on the fuel type and scope of infrastructure changes.
Run the DIY vs. pro decisionCheck a quote you already have

When this cannot wait

  • Tank failed and you want to switch technology rather than replace like-for-like
  • Running out of hot water regularly with a properly sized tank
  • Wanting to reclaim closet or garage space occupied by a tank

Common questions

How much does it cost to convert to a tankless water heater?
A gas tankless conversion typically runs $3,500 to $7,000 installed, including the unit, venting, and gas line work. Electric conversions run $2,500 to $5,000 but may need a panel upgrade that adds $2,000 to $4,000.
Is converting to tankless worth it?
Tankless units last longer and save space, but the conversion premium over a tank replacement is $2,000 to $4,000. Energy savings are $50 to $100 per year. The payback on conversion cost alone is 20 to 40 years — justify it on space, endless hot water, or a failed tank, not energy savings alone.
What is needed to convert from tank to tankless?
Gas: larger gas line, new stainless venting, new water connections, and possibly a condensate drain. Electric: dedicated high-amperage circuit and often a panel upgrade. Both need a permit and professional installation.
What size tankless water heater do I need to replace a 50 gallon tank?
A 50-gallon tank provides roughly 7 GPM during peak demand. You need a gas tankless rated at 7 to 8 GPM at your local groundwater temperature rise. In northern climates, that means a 199,000 BTU unit.
Water heater burst and I want tankless this time — conversion cost?
Emergency tankless conversion runs $3,500 to $7,000 for gas (including venting and gas line upsizing) or $2,500 to $5,000 for electric. Add $2,000 to $4,000 if a panel upgrade is needed for electric. A like-for-like tank swap is faster (same day) and $2,000 to $4,000 cheaper.
Not enough hot water for 4 people — tankless conversion cost?
A properly sized gas tankless (199,000 BTU) delivers endless hot water for 4+ people at $3,500 to $7,000 installed. Undersized units cause the cold-water sandwich effect. A 50-gallon heat pump tank ($2,200 to $4,500) is an alternative with simpler installation.
Electric tankless water heater tripping the breaker — conversion cost?
Electric tankless units draw 80 to 120 amps — most homes need a panel upgrade ($2,000 to $4,000) plus the unit install ($2,500 to $5,000). Total: $4,500 to $9,000. Gas tankless avoids the electrical demand at $3,500 to $7,000 if gas is available.
How much does it cost to convert a gas tank to tankless, including venting?
Gas conversion runs $3,500 to $7,000 including stainless venting ($500 to $1,500), gas line upsizing ($300 to $800), and condensate drain ($100 to $300). A direct vent through the wall is cheaper than vertical venting through the roof.
Tankless water heater cold-water sandwich problem — is converting worth it?
The cold-water sandwich (brief cold burst between hot draws) is reduced with a recirculation pump ($300 to $600 added). If sandwich effect is your main concern, a heat pump tank ($2,200 to $4,500) stores hot water without the conversion complexity.
Can I get a tankless unit installed the same day as old tank removal — what does it cost?
Like-for-like tank swap: same day, $1,200 to $2,400. Tankless conversion: 1 to 3 days, $3,500 to $7,000 because venting and gas line work cannot be rushed. If you need hot water tonight, install a tank now and plan tankless conversion for later.

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