Electricity Bill Calculator
Estimate a full electricity bill including tiered rates, standing charge and tax.
Please note: For planning and educational use only. Electrical installation is governed by wiring regulations and is dangerous when done incorrectly. Always have work designed, installed and inspected by a qualified electrician.
What the Electricity Bill Calculator does
An electricity bill combines a per-unit energy charge with a fixed daily standing charge and tax. On tiered tariffs each band is charged at its own rate, so the effective rate per unit rises with consumption.
Formula
Energy charge = Σ (Units in each band × Band rate)Standing charge = Daily rate × Billing daysTotal = (Energy + Standing) × (1 + Tax rate)Effective rate = Total ÷ Units used
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Units used | kWh | Yes | Accepts 0 or more. |
| Tariff type | one of 2 options | Yes | — |
| Rate per kWh | selected currency | In some modes | Accepts 0 or more. Shown Tariff type is Flat rate. |
| Tier 1 limit | kWh | In some modes | Accepts 0 or more. Shown Tariff type is Tiered rates. |
| Tier 1 rate | selected currency | In some modes | Accepts 0 or more. Shown Tariff type is Tiered rates. |
| Tier 2 limit | kWh | In some modes | Accepts 0 or more. Shown Tariff type is Tiered rates. |
| Tier 2 rate | selected currency | In some modes | Accepts 0 or more. Shown Tariff type is Tiered rates. |
| Rate above tier 2 | selected currency | In some modes | Accepts 0 or more. Shown Tariff type is Tiered rates. |
| Standing charge per day | selected currency | Optional | Accepts 0 or more. |
| Billing period | days | Yes | Accepts 1 or more. |
| Tax or VAT | % | Optional | — |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Tariff type and Currency.
- Enter Units used and Billing period.
- Fill in the remaining inputs the form shows for your choice.
- Optionally add Standing charge per day and Tax or VAT.
- Select Calculate.
Worked example
350 kWh over 30 days on tiers of 100 kWh at 0.18, next 200 at 0.26, rest at 0.34, with 0.50 standing and 5% tax.
- Units
- 350
- Tariff
- Tiered
- Standing
- 0.50
- Days
- 30
- Tax
- 5
18.00 + 52.00 + 17.00 = 87.00 energy, plus 15.00 standing = 102.00, plus 5.10 tax = 107.10 total.
Frequently asked questions
What is a standing charge?
A fixed daily fee covering network and metering costs. It applies regardless of usage, so a low-consumption household pays a much higher effective rate per unit.
Method and sources
Method. Consumption charged against the tariff structure entered — flat, tiered or time-of-use — plus standing charges and tax.
Applies to. None — you supply the tariff structure
Assumptions
- The band limits and rates entered match the supply agreement, and the billing period aligns with the consumption figure.
Limitations
- Tariff structures vary widely and change; the calculator ships none and models only what is entered.
- Where bands reset monthly, applying them to an annual figure understates the charge substantially.
- Estimated rather than metered readings are a common source of difference between this and an actual bill.
Sources
- Your own supply agreement and bill — Varies by supplier. The band limits, unit rates, standing charge and tax treatment, none of which ship with this calculator.