Example result based on the prefilled values.
Annual Electricity Cost
£1,018.15
Annual Gas Cost
£985.60
Total Annual Bill
£2,003.75
Monthly Average
£166.98
Saving vs Price Cap
£0.00
Continue your plan
Useful next calculations
Rates & sources1 Jul – 30 Sep 2026
Ofgem average Direct Debit unit rates and standing charges for Great Britain from 1 July to 30 September 2026. Actual rates vary by region, payment method and meter type.
Source: Ofgem — Energy price cap unit rates and standing charges — source checked for 1 Jul – 30 Sep 2026.
When to use this calculator
- Before switching supplier, upgrading equipment, or comparing energy-saving changes.
- When you want to test different usage assumptions or price scenarios quickly.
- When you need a simple estimate before requesting installer or supplier quotes.
- When you are evaluating solar panels, a heat pump, or insulation and want to check the payback period before spending.
- When your tariff is about to change and you want to quickly model the impact on your annual energy bill.
A realistic UK planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Annual Electricity Usage (kWh)
35
Annual Gas Usage (kWh)
35
Your Current Tariff
Ofgem price cap (standard)
Electricity Unit Rate (p/kWh) — if fixed
5%
After entering these figures, review annual electricity cost, annual gas cost and total annual bill together rather than in isolation — each metric tells a different part of the story. Then rerun the tool with one input adjusted to see which variable has the biggest effect on all three outputs before you settle on a plan.
How to read your results
Annual Electricity Cost
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Annual Gas Cost
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Total Annual Bill
This is the headline outcome of the calculation, but it is most useful when read alongside the supporting metrics below it rather than in isolation. Try changing one input at a time and watching how this total moves to understand which driver has the biggest impact.
Monthly Average
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Saving vs Price Cap
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Method & assumptionsAuthoritative sources
This calculator uses Ofgem’s Great Britain average Direct Debit rates for 1 July to 30 September 2026: 26.11p/kWh electricity, 7.33p/kWh gas, and daily standing charges of 57.19p and 29.04p respectively. They include VAT and are rounded to two decimal places. They are averages for England, Scotland and Wales; actual capped rates vary by region, payment method and meter type.
For a fixed tariff, enter the unit rates and standing charges from your tariff information. The tool annualises daily standing charges over 365 days and estimates usage costs from the kWh entered. It is a budgeting comparison, not a bill, price forecast or switching recommendation; check your supplier’s rates and terms before acting.
Common mistakes
- !Using optimistic assumptions without testing a more cautious scenario as well.
- !Comparing outputs from different tools without checking that the inputs match.
- !Treating the result as a final quote instead of a planning estimate.
- !Using the current tariff rate without accounting for future price changes, which can make payback calculations look more favourable than they really are.
- !Forgetting to include the standing charge when comparing annual energy costs, which can be a significant portion of a typical bill.
What to do next
- Run the same scenario with a 10% higher unit rate to see how your figures would look if prices rise.
- Compare this result with a related energy or insulation calculator before requesting installer quotes.
- Use the linked guides to understand export tariffs, grant eligibility, or supplier comparison approaches.
- If you are evaluating an upgrade, get at least two installer quotes and rerun this calculator with the actual cost figures before committing.
- Set a reminder to rerun the calculation when your tariff renews, so the payback estimate stays accurate.
Frequently asked
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