Water Heater Cost Calculator — Formula
## Water Heater Operating Cost
Water heating is the second largest energy expense in most homes, accounting for 14-18% of utility bills.
### Formula
**Daily BTU = Gallons/Day x 8.33 (lbs/gal) x Temp Rise (°F)**
**Daily Therms = Daily BTU / 100,000 / Efficiency**
**Monthly Cost = Daily Therms x 30.44 x Cost per Therm**
8.33 is the weight of one gallon of water in pounds. One BTU raises one pound of water by 1°F.
Water heating is the second largest energy expense in most homes, accounting for 14-18% of utility bills.
### Formula
**Daily BTU = Gallons/Day x 8.33 (lbs/gal) x Temp Rise (°F)**
**Daily Therms = Daily BTU / 100,000 / Efficiency**
**Monthly Cost = Daily Therms x 30.44 x Cost per Therm**
8.33 is the weight of one gallon of water in pounds. One BTU raises one pound of water by 1°F.
Esempio Risolto
50 gallons/day, 60°F temperature rise, 92% efficient gas heater at $1.20/therm.
- Daily BTU = 50 x 8.33 x 60 = 24,990 BTU
- Daily therms = 24,990 / 100,000 / 0.92 = 0.272 therms
- Monthly cost = 0.272 x 30.44 x $1.20 = $9.93
- Annual cost = 0.272 x 365 x $1.20 = $119.07