Time-of-Use Savings Calculator
Your bill on a time-of-use tariff from how your usage splits across peak, shoulder and off-peak — what moving a share of the peak to off-peak saves, and whether the time-of-use tariff beats a flat rate at all.
Time-of-use tariffs charge two or three times as much in the evening peak as overnight.
How the time-of-use savings calculator works
Time-of-use tariffs charge two or three times as much in the evening peak as overnight. The bill is the usage in each window at its rate; the saving from shifting is the peak energy moved times the difference in rates. Whether the tariff beats a flat rate depends on your split: a home that uses most of its power in the evening can pay more on time-of-use than on the flat rate it replaced.
Formula: cost = Σ usage_window × rate_window; shift saving = shifted kWh × (peak rate − off-peak rate)
Worked examples
| Inputs | Monthly usage cost now | Note |
|---|---|---|
| 40% of usage in the peak | 185.4 | dearer than flat until you shift |
| A daytime household | 157.2 | time-of-use wins |
| Nothing shiftable | 185.4 | no saving |
FAQFrequently asked questions
What is a time-of-use tariff?
One that charges different rates by time of day: a high peak in the late afternoon and evening, a low off-peak overnight, and often a shoulder between. It rewards moving usage away from the evening.
What can I actually shift?
Dishwashers, washing machines, dryers, pool pumps, hot-water systems and electric-car charging — on timers, most of it moves without noticing. Cooking and evening lighting do not.
Is time-of-use cheaper than a flat rate?
Only if enough of your usage is outside the peak. The break-even peak share row says how much; a home at 40% peak usually pays more until it shifts.
How do I find my split?
Interval data from a smart meter, available from most retailers as a download. Without it, estimate from habits: an evening-heavy household is 35 to 45% peak.
What about solar homes?
Solar covers the shoulder and reduces daytime imports, leaving the evening peak — which makes time-of-use tariffs worse for solar homes unless they have a battery.
Where these figures come from
- International Energy Agency — Energy Efficiency — appliance consumption and standby power context
- Australian Energy Regulator — the Australian energy market regulator
Last checked: September 2026. Appliance power figures are typical ratings; check the label on your own equipment, which is authoritative for it.