Useful next calculations
Rates and sources
UK energy unit rates vary by region and supplier. Ofgem publishes a price cap refreshed each quarter.
Source: Ofgem — Energy price cap. Check the linked guidance and any live quote before acting.
When to use this calculator
- Before switching supplier, upgrading equipment or comparing energy-saving changes.
- When you want to test different usage or price scenarios quickly.
- When you need a simple estimate before requesting installer or supplier quotes.
- When a tariff is about to change and you want to model the bill impact.
A worked example
These are the example figures the calculator opens with.
| Input | Value |
|---|---|
| Gas Usage Per Day (m³) | 4 |
| Unit Rate (p/kWh) | 5.5 |
| Standing Charge (p/day) | 30 |
For those figures the calculator returns:
- Daily usage: 44.80kWh
- Monthly cost: £84.03
- Annual: £1,008.86
Method & assumptions
This calculator works out your estimated gas bill by taking your average daily usage in kWh, multiplying it by the unit rate on your tariff, and adding the daily standing charge over your chosen period. Usage figures can be found on a recent gas bill or taken from a smart meter in-home display. Because gas consumption varies significantly with the seasons, the calculator is most accurate when you enter usage figures that reflect the period you are planning for — use a winter month's reading to project winter costs rather than an annual average. Gas VAT in Great Britain is charged at the reduced rate of 5%, and suppliers quote their rates inclusive of this, so no additional adjustment is needed. Actual bills may differ due to meter reading cycles, direct debit smoothing, and any standing charge changes mid-contract.
Common mistakes
- Using the current tariff without testing a higher unit rate.
- Forgetting the standing charge when comparing annual bills.
- Treating the result as a supplier quote.
- Using optimistic savings figures for an upgrade without a written estimate.
What to do next
- Run the same scenario with a 10% higher unit rate.
- Compare this result with a related energy calculator before requesting installer quotes.
- If you are evaluating an upgrade, rerun with actual quote figures.
- Set a reminder to rerun the calculation when your tariff renews.