Australia · AUD
Time-of-Use Electricity Calculator Australia
Compare the same household electricity use on a flat-rate plan and a time-of-use plan. Enter peak, off-peak and optional third-period energy, with each plan’s own daily supply charge.
Compare your two electricity plans
Use the same billing days and total electricity imported from the grid for both plans. Enter each plan's prices and daily charge, including an explicit 0 where no daily charge applies.
Enter 30 for A$0.30/kWh. Use prices with applicable tax included. Zero and negative unit prices are supported; each entered price stays constant for this comparison.
Enter each daily charge separately in cents, including applicable tax. It is charged once per day for the connection.
Flat-rate plan
Energy + daily charges for your period
- Energy charge
- Daily charges
Time-of-use plan
Energy + daily charges for your period
- Energy charge
- Daily charges
- Total grid import
- Peak share
- Off-peak share
- Third-period share
- Average time-of-use energy price
The average energy price excludes daily charges. Shares are undefined when total import is zero. Displayed values are rounded; comparisons use unrounded inputs.
Enter your billing days, energy and both plans to compare their charges.
Enter valid prices and an energy split to find a break-even share.
Calculation and comparison limits
Single/flat-rate total = total imported kWh × its unit price ÷ 100 + billing days × its daily charge ÷ 100. Time-of-use total = (peak kWh × peak price + off-peak kWh × off-peak price + any third-period kWh × its price) ÷ 100 + billing days × its daily charge ÷ 100.
For break-even, K is total kWh, D is days and f is the third-period fraction, or 0 with two periods. The off-peak fraction of total energy at equality is [K × (peak price × (1 − f) + third price × f − flat price) + D × (time-of-use daily charge − flat daily charge)] ÷ [K × (peak price − off-peak price)]. Prices and charges use the same pence or cents units. Keep the third-period share fixed and move energy only between peak and off-peak. The possible off-peak range is 0 to (1 − f). Equal peak/off-peak prices and zero imported energy need separate treatment.
This compares the entered energy and daily charges only, for the entered period. It does not forecast annual use, infer electricity from clock hours, choose a retailer or establish eligibility. Dynamic interval settlement, solar export credits, demand charges, block/tier prices, controlled-load circuits, add-ons, discounts and other fees are excluded. Check the actual tariff's time windows and terms before relying on a scenario. Your entries remain in this tab and are not saved or sent.
Use the same household energy and billing days
Start with imported electricity over one clearly defined period. For cumulative meter registers, use the end reading minus the start reading for each matching register. Confirm which register belongs to each price band. Each kWh must appear once, and all readings must cover the same elapsed days.
The flat or single-rate plan prices the sum of that energy. The time-of-use plan prices the amount assigned to each of its own periods. If you are considering a tariff with different time windows, your existing bill's band totals may not match: use suitable interval data or label the new split as an estimate. A share is a percentage of total kWh, not of hours, appliances or the cost.
Use the whole household's relevant grid import when comparing a whole-house tariff. An EV charging session or a heater reading alone does not capture a price change affecting the rest of the home. Electricity used directly from solar and electricity exported to the grid are not imported energy. Do not subtract exported kWh from the imported kWh entered here.
Match the retailer’s periods and supply charge
Ausgrid explains that a retailer's time-of-use periods can differ from the network's periods. Use the retailer's actual windows and retail prices, with any applicable weekday, weekend or seasonal differences. The calculator supplies no Australian timetable or national tariff.
If your plan has a shoulder or another third period, give it its own imported kWh and price. Do not combine differently priced energy into a peak band without calculating the correct energy-weighted price. Plans with more periods or additional charging structures need a more complete model.
Enter each plan's own supply charge in cents per day. A daily charge is added once for each billing day, even when imported kWh is zero. Use prices with applicable tax included on the same basis; do not add tax again to a tax-inclusive quote. If prices change during the period, calculate the affected portions separately.
A worked comparison with illustrative prices
These figures demonstrate the arithmetic. They are invented scenarios, not current tariffs, recommended plans, typical household use or a forecast. The example stays fixed when you edit the calculator.
Suppose the household imports 300 kWh over 30 days. A flat plan charging 30c/kWh and 100c/day costs A$120: A$90 for energy plus A$30 in supply charges.
For a time-of-use plan, enter 120 peak kWh at 40c, 120 off-peak kWh at 20c and 60 third-period kWh at 30c, with a supply charge of 110c/day. Energy costs A$48 + A$24 + A$18 = A$90; supply charges add A$33. Its total is A$123, so the flat plan costs A$3 less.
Keep the third period at 60 kWh, or 20% of the total. The equal-cost off-peak share is 45% of total imported kWh: 135 off-peak kWh, 105 peak kWh and the same 60 third-period kWh. Energy then costs A$87 and supply charges add A$33, matching A$120. The time-of-use plan costs less above 45%, up to the possible maximum of 80% while the third share stays fixed.
Read the break-even result within its limits
The break-even calculation holds total imported kWh, billing days, prices and daily charges constant. With three periods, it also holds the third-period share constant. Only energy assigned to peak/day and off-peak/night changes. Moving several devices may not achieve that split, and a short meter sample may not represent a heating season or a year.
A cheaper off-peak rate can produce a minimum off-peak share; reversed prices reverse which side costs less. Equal prices may make the split irrelevant. A boundary can be a tie, or there may be no equal-cost share in the possible range. With zero imported kWh, only daily charges can be compared.
This tool uses two or three entered energy prices held constant for the period. It does not settle dynamic interval prices or calculate demand charges, export credits, controlled-load circuits, usage tiers, discounts, subscriptions, exit fees or meter-change fees. Check these items and tariff eligibility before deciding to switch. For a single appliance at one usage price, use the Australian electricity cost calculator.
Common questions
Is time-of-use electricity cheaper than a flat rate?
It depends on your imported kWh in each time period and both plans’ unit prices and daily supply charges. A lower off-peak price does not guarantee a lower total. Compare the same household energy over the same billing days, using the time windows and retail rates of the plan you are considering.
How do I include a shoulder or third electricity period?
Choose three periods and enter its kWh or percentage of total imported energy, plus its own cents-per-kWh price. Use the third band for the additional period on your plan; its label and hours are not assumed. For break-even, the calculator holds that third-period share fixed and moves energy only between peak and off-peak.
Are off-peak hours the same across Australia?
No universal timetable is applied here. Ausgrid explains that retail time-of-use periods can differ from its network periods and that retailers decide how network charges feed into retail pricing. Use your own retailer’s applicable time windows and prices, including any differences by day or season.
Is controlled load the same as using an appliance off-peak?
This calculator compares the household grid import assigned to the entered time periods. A separate controlled-load circuit or meter is outside that model and must not be added as though it were an off-peak discount on every household appliance. Check which loads, energy readings and extra charges belong to your actual plan.
Can I compare solar, a demand tariff or dynamic prices?
This tool prices grid-imported electricity at two or three entered time-band prices, plus a daily supply charge. It does not settle dynamic interval prices, calculate demand charges, deduct solar exports or model battery operation, controlled load, usage tiers, discounts or add-ons. A plan with those features needs a more complete comparison.
Should I enter dollars or cents for the supply charge?
Enter cents per day: for example, enter 110 for A$1.10 per day. Enter usage prices in cents per kWh. Use amounts with applicable tax included consistently for both plans, and enter 0 explicitly if a daily charge is zero. The connection charge is added once per billing day, not once per appliance.
More Australian calculators
Sources and checking your inputs
- Ausgrid: optimising your electricity usage — Retail time windows and prices can differ from network arrangements. A time-of-use plan does not automatically make the total bill cheaper. Its example rates are not used here.
- Ausgrid: demystifying your electricity costs — Distinguishes kWh-based usage charges from a fixed daily supply charge, which applies on each billing day independently of energy used.
- Ausgrid: time-of-use prices — Retailers may use different time windows and rates from the network. Its network-specific timetable is not a national retail schedule.
- Ausgrid: introduction to demand pricing — Demand pricing adds a separate component that cannot be determined from total kWh or an off-peak energy share. Retail calculation methods vary.
- Ausgrid: controlled-load pricing — Describes permanently connected appliances on separately wired circuits with limited switching times. That supply is separate from the household time-band comparison here.
Ausgrid's network guidance supports these input definitions and limits; it does not establish the terms or availability of every Australian retail plan.
Source review: 3 October 2026. These sources support tariff definitions and input guidance; all prices and energy in the calculator come from your entries. The worked examples are illustrative. Report a correction.