Time-of-use calculator.

The formula

Saving = cycle kWh × cycles × (peak rate − off-peak rate)

A worked example

Twenty hypothetical cycles using 1 kWh each cost $6 at $0.30/kWh, or $3 at $0.15/kWh. The difference is $3. This is not a claim about a particular appliance or tariff.

What must be true

You must have different prices during different hours. The complete use must fall within the intended price window. Your supplier defines those hours, including weekend, season, and holiday rules.

On a flat-rate tariff, timing alone does not change the price per kWh. Equal rates correctly show zero savings. If the off-peak number is higher, the calculator shows a negative saving.

Cycles that cross a boundary

If part of a cycle runs at another price, divide its measured kWh into those periods. Calculate each portion separately. Do not charge every kWh at the starting-hour rate unless your tariff does that.

Whole-plan limits

A time-of-use plan can make other household use more expensive. This tool excludes fixed fees, demand charges, export rates, tier changes, and all other devices. It cannot show whether switching tariff plans saves money.

Check safety and the appliance manual before delayed operation. Do not run a dryer or portable heater unattended to seek a cheaper rate. Read the time-of-use guide.

Source

NSW Government: Time-of-use tariffs explains flat-rate and time-of-use tariffs. Use your own supplier's current schedule.