Shower Cost Calculator
Find what each shower costs in water and energy, and what the habit adds up to over a year.
Formula and sources updated · Data sources · 1View algorithm, constants and default inputs (JSON)
Breakdown
About this calculator
Estimate shower water and heating cost from flow, duration, water temperatures, heater efficiency and your entered utility rates. The model includes only water volume and the heat needed to raise it from inlet to outlet temperature; it excludes standby losses, pipe losses and other household energy use.
Worked example
calculated with the default values below
Minutes per shower 10 min · Showerhead flow rate 2 gpm · Showers per week 7 · People in the household 3 · Water rate 4.5 $/1000 gal · Energy rate 0.17 $/kWh · Cold water temperature 60 °F · Shower temperature 105 °F · Water heater efficiency 90 % Total cost per shower 0.506 $ · Water per shower 20.0 gal · Water cost per shower 0.090 $ · Energy cost per shower 0.416 $ · Household cost per year 552.04 $ · Water used per year 21,840 gal
Method and assumptions
G = t×f; E = G×8.34×(T_o−T_i)×100÷η÷3412; C = G÷1000×r_w + E×r_e; Y = C×n×52×p 8.34 lb/gal is water weight; 3412 BTU = 1 kWh; yearly cost uses n showers/week × 52 weeks × p people. Estimate shower water and heating cost from flow, duration, water temperatures, heater efficiency and your entered utility rates. The model includes only water volume and the heat needed to raise it from inlet to outlet temperature; it excludes standby losses, pipe losses and other household energy use. Use the cited guidance and your own measurements, bills or product specifications to choose inputs. Sample defaults are not current local data.
Data sources
Use the cited guidance and your own measurements, bills or product specifications to choose inputs. Sample defaults are not current local data.
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
G = t×f; E = G×8.34×(T_o−T_i)×100÷η÷3412; C = G÷1000×r_w + E×r_e; Y = C×n×52×p
- t
- Shower duration (min)
- f
- Flow rate (gal/min)
- η
- Water heater efficiency (%)
- T_o
- Outlet temp (°F)
- T_i
- Inlet temp (°F)
- r_w
- Water rate ($/1,000 gal)
- C
- Cost per shower
- r_e
- Energy rate ($/kWh)
- n
- Showers per week
- p
- People in household
- G
- Water used per shower (gal)
- E
- Energy per shower (kWh)
- Y
- Yearly household cost ($)
8.34 lb/gal is water weight; 3412 BTU = 1 kWh; yearly cost uses n showers/week × 52 weeks × p people.
Frequently asked questions
Why does heating water cost more than the water itself in a shower?
At the default 2 gpm for 10 minutes you use 20 gallons; warming it from 60°F to 105°F needs about 2.4 kWh at 90% heater efficiency, which at $0.17/kWh costs roughly 42 cents, while the water itself is only about 9 cents. Heating is therefore the bulk of the shower cost unless electricity is very cheap. Longer or hotter showers widen the gap because energy scales with both time and temperature rise.
Which inputs and limits apply to Shower Cost Calculator?
Use the units shown beside each field. These are form limits, not recommended settings. Minutes per shower: 0–60 min; Showerhead flow rate: 0.5–10 gpm; Showers per week: 0–21; People in the household: 1–20; Water rate: 0–50 $/1000 gal; Energy rate: 0–5 $/kWh; Cold water temperature: 32–90 °F; Shower temperature: 80–130 °F; Water heater efficiency: 50–100 % G = t×f; E = G×8.34×(T_o−T_i)×100÷η÷3412; C = G÷1000×r_w + E×r_e; Y = C×n×52×p 8.34 lb/gal is water weight; 3412 BTU = 1 kWh; yearly cost uses n showers/week × 52 weeks × p people. Estimate shower water and heating cost from flow, duration, water temperatures, heater efficiency and your entered utility rates. The model includes only water volume and the heat needed to raise it from inlet to outlet temperature; it excludes standby losses, pipe losses and other household energy use. Use the cited guidance and your own measurements, bills or product specifications to choose inputs. Sample defaults are not current local data.
What is a complete worked example for Minutes per shower = 10 min; Showerhead flow rate = 2 gpm?
Inputs: Minutes per shower = 10 min; Showerhead flow rate = 2 gpm; Showers per week = 7; People in the household = 3; Water rate = 4.5 $/1000 gal; Energy rate = 0.17 $/kWh; Cold water temperature = 60 °F; Shower temperature = 105 °F; Water heater efficiency = 90 %. Calculation: G = t×f; E = G×8.34×(T_o−T_i)×100÷η÷3412; C = G÷1000×r_w + E×r_e; Y = C×n×52×p. Results: Total cost per shower = 0.506 $; Water per shower = 20.0 gal; Water cost per shower = 0.090 $; Energy cost per shower = 0.416 $; Household cost per year = 552.04 $; Water used per year = 21,840 gal.