Tankless water heater sizing Last reviewed June 30, 2026
Tankless Water Heater Installation Cost Guide
By the WhatSize editorial team 4 min read Standards-reviewed
Tankless installation costs $1,000–$3,500 (electric) or $1,400–$3,500 (gas) per Fixr 2025 cost guide. National average whole-tankless installed: $2,811. DIY for electric with existing wiring only.
Why tankless installation costs more than tank
Tankless water heater installation costs more than standard tank installation due to gas line upgrades, venting, electrical panel work, and permits. Per Fixr 2025 cost guide (last updated January 31, 2025, most recent nationwide data):
National averages (installed):
- Electric: $1,000–$3,000 (avg $2,500)
- Natural gas: $1,400–$3,500
- Propane: $1,400–$3,500
- Oil: $1,500–$4,500
- Solar whole-house: $3,000–$8,000
- Whole-tankless national average: $2,811
Equipment-only cost by brand (Fixr, US market 2024–2025):
- Bosch: Electric $140–$800; Gas $1,050–$2,250
- Rheem: Electric $170–$575; Gas $670–$1,950
- EcoSmart: Electric $425–$725; Gas $695–$1,600
- Takagi: Gas only $490–$1,225
- Noritz: Gas only $515–$1,700
- Rinnai: Gas only $900–$1,995
- Navien: Gas only $1,075–$1,535
- AO Smith: Gas only $300–$670
Hidden add-on costs (Fixr):
- Gas line run/upgrade: up to $800
- Electrical panel upgrade for electric whole-house: $500–$1,500
- Venting through wall/roof: $200–$1,000
- Condensate drain / neutralizer (condensing gas): $150–$400
- Permit: $50–$300
- Old tank removal/disposal: up to $500
Operating cost (Fixr): gas tankless $250/year, propane tankless $350/year, electric tankless $600/year. Per DOE, tankless saves 24–34% vs tank for households using ×41 gal/day.
Top picks for this size
These Amazon-available picks meet the calculated spec. For region-specific or licensed contractor-installed options, consult a local professional. See our Disclaimers.
Cost breakdown by scenario
- Electric tankless, existing wiring: $800–$2,000 installed.
- Gas tankless, existing gas line + venting: $1,500–$2,500 installed.
- Gas tankless, new gas line upgrade: $2,500–$4,000 installed.
- Gas tankless, full conversion: $3,500–$5,500 installed.
- DIY (electric only): $500–$1,500 for unit + parts.
Frequently asked questions
How much does it cost to install a tankless water heater?
Per Fixr 2025: Electric $800–$2,000 installed; Gas $1,500–$3,500 installed. Whole-tankless national average $2,811. Full conversion (new gas line + venting + electrical) can reach $5,500.
Can I install a tankless water heater myself?
Electric tankless: possible DIY with basic electrical skills and existing wiring. Gas tankless: NOT recommended for DIY — gas line work, venting, and condensate drain all require professional installation in most US jurisdictions. Permits and inspections required.
What's the cheapest way to install tankless?
Save the most by buying the unit yourself and hiring a plumber only for the gas line + venting (if doing electrical and mounting yourself). For pure DIY electric, save $500–$1,000 on installation costs. Total potential savings vs full pro install: $1,000–$2,000.
Does installing tankless require a permit?
Yes in most US jurisdictions. Permit fees: $50–$300. Work must be inspected by a local building inspector. DIY installations typically require the homeowner to pull their own permit. Skipping permits can cause issues when selling the home and may void homeowner insurance coverage for water damage.
You might also need
More tankless water heater sizing guides
- What Size Tankless Water Heater for a Family of 4?
- What Size Tankless Water Heater for a Family of 2—?
- What Size Tankless Water Heater for a Family of 5—?
- Electric Tankless Water Heater Sizing Guide
- Gas Tankless Water Heater Sizing Guide
- Electric vs Gas Tankless Water Heater: Which Size & Type?
- Heat Pump vs Tankless Water Heater: Size & Efficiency
- Tankless Water Heater Sizing for Cold Climates
- Propane Tankless Water Heater Sizing Guide
- RV Tankless Water Heater Sizing Guide
Still choosing between sizes? Compare: tankless vs tank