Gas Water Heater Running Cost
See exactly what your gas water heater costs per day, month and year at current US gas rates.
A 50-gallon gas water heater costs roughly $0.66/day, $20/month, and $241/year for a family of 4 at the US average gas rate of $1.20/therm.
Calculate Gas Water Heater Cost
Gas Water Heater Monthly Cost by Type (US 2026)
| Type | 1–2 People | 3–4 People | 5+ People |
|---|---|---|---|
| Gas Tank 30 gal | ~$8/mo | ~$13/mo | ~$18/mo |
| Gas Tank 40 gal | ~$9/mo | ~$16/mo | ~$23/mo |
| Gas Tank 50 gal | ~$10/mo | ~$20/mo | ~$30/mo |
| Tankless Gas | ~$8/mo | ~$17/mo | ~$26/mo |
Gas $1.20/therm. Tank 80% eff. Tankless 94% eff. 120°F target. US 2026 average rates.
Gas Tank vs Tankless Gas Water Heater Cost
Tankless gas water heaters cost roughly 15% less per month than gas tank heaters for equal hot water output. This is due to their higher efficiency rating of 94% versus 80% for standard tank models. The savings are most significant for larger households using 5+ people worth of hot water daily.
Gas tank heaters have lower upfront costs and simpler installation than tankless models. For smaller households using 20–30 gallons per day the monthly cost difference between tank and tankless is only $1–$3, making the cheaper upfront tank model the practical choice.
Gas prices vary significantly across US states. In 2026 rates range from $0.80/therm in Louisiana to $2.10/therm in Hawaii. Use the calculator above with your local gas rate for an accurate monthly estimate. You can also compare against electric water heater running costs or view the full water heater cost calculator to compare all types side by side.
Gas Water Heater Cost — FAQs
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