Budget electric hot water across two rate windows
A renter has an electric resistance heater and a measured 50 L hot draw at a 35°C rise. Assume a fictional tariff of USD 0.32/kWh at peak time and USD 0.16/kWh off-peak. Compare the same heat requirement under each rate.
Open CalculatorInputs and calculation
| Tool input | Value |
|---|---|
| Currency | USD |
| Volume or billing unit | liters |
| Volume (L) | 50 |
| Temperature rise (°C) | 35 |
| Heating method | Electric resistance |
| Efficiency (%) | 100 |
| Energy price (USD per input kWh) | 0.32 |
| Water price (USD/L) | 0 |
Heat delivered = 50 × 35 × 0.001163 kWh. Divide by 1 to get about 2.0353 input kWh. Multiply input energy by 0.32, add 50 × 0 for water, then round to USD 0.65.
Tool result · USD 0.65
| Tool input | Value |
|---|---|
| Currency | USD |
| Volume or billing unit | liters |
| Volume (L) | 50 |
| Temperature rise (°C) | 35 |
| Heating method | Electric resistance |
| Efficiency (%) | 100 |
| Energy price (USD per input kWh) | 0.16 |
| Water price (USD/L) | 0 |
Heat delivered = 50 × 35 × 0.001163 kWh. Divide by 1 to get about 2.0353 input kWh. Multiply input energy by 0.16, add 50 × 0 for water, then round to USD 0.33.
Tool result · USD 0.33
What the comparison shows
The price is halved before rounding and modeled energy stays constant. Verify the heater’s actual reheat schedule before estimating a time-of-use bill.
Assumptions and limits
A real tank can reheat outside the draw window. This comparison assumes the full modeled input is purchased in the stated window.