Demand charge estimate calculator

Use this calculator when the tariff question depends on peak demand rather than only kWh. Australian commercial and industrial bills may include demand components, but the exact billing basis depends on retailer, network tariff, meter, NMI, contract, GST and site-specific rules. This page keeps the arithmetic visible after the user enters the relevant demand and rate values.

The calculator estimates a demand-charge component. It does not read a bill, decide a network tariff, apply ratchets, handle seasonal time windows, include energy charges, include fixed supply charges or make a savings claim.

Field Use Cases

This page is most useful when the demand value and rate come from the same source context. A peak kW from one period and a demand rate from a different tariff class can create a misleading number.

Tariff Boundary

The narrow boundary protects the page from becoming a bill interpretation tool. It is a demand-charge worksheet for values the user has already sourced.

Input Checklist

If the source tariff bills kVA directly or uses another basis, convert the value externally or record the assumption clearly before entering it here.

Review Workflow

1. Identify the site, meter, NMI, tariff schedule or demand record.
2. Confirm whether the peak demand input is kW or kVA.
3. If using kVA, enter the power factor that belongs to the same demand condition.
4. Enter the demand rate in AUD/kW/month from a documented source.
5. Enter the number of billing months being estimated.
6. Read billing demand, monthly charge, period charge and annualised charge together.
7. If the period is longer than 12 months, check tariff resets, contract changes, ratchets and annualisation assumptions.
8. Keep energy charges, fixed charges and GST outside this record unless they are calculated in neighbouring tools.
9. Export only when the demand source, rate source and period are recorded.

The workflow supports early review without pretending that demand billing is universal across retailers or network tariffs.

Worked Australian Examples

These examples are not bill corrections. They show the arithmetic after the demand value and rate have been sourced by the user.

Related Tools

Use energy cost when the bill component is kWh multiplied by an entered c/kWh value. Use tariff scenario cost when two energy-rate and supply-charge assumptions need comparison. Use kVA, kW and PF when the relationship between apparent power, real power and power factor needs a separate record. Use the power-factor relationship chart when reviewing how kVA and kW relate before entering a billing basis.

Stop Points

• The demand rate unit is not AUD/kW/month or has not been converted.
• The tariff bills on a different basis and that basis is not documented.
• Peak demand, power factor and rate come from unrelated periods or sites.
• Ratchets, seasonal windows or contract clauses control the actual charge.
• GST, fixed charges or energy charges are being silently included or excluded.
• The result is being used as a savings claim without the actual bill and tariff schedule.

Keep the demand value, unit basis, power factor, rate source, billing period and reviewer notes with the export. The output is a demand-charge estimate, not a retailer contract interpretation.