UK Gas Bill Calculator

Uses the current Ofgem price cap (Jul–Sep 2026). Estimate your bill, or convert an actual meter reading (m³ or ft³) straight to kWh and cost.

✓ Free to use ✓ Current Ofgem rates ✓ Meter reading converter ✓ Shareable results

What do you want to calculate?

Average Usage (kWh/day)

Billing Period (days)

▸ Adjust rates (your actual tariff)

Unit Rate (p/kWh)

Standing Charge (p/day)

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Why your meter doesn't read in kWh

Gas meters measure volume — cubic metres (most modern meters) or cubic feet (older imperial meters) — not energy. Your supplier converts that volume into kWh using a standard formula: kWh = volume(m³) × 1.02264 (volume correction factor) × calorific value (typically ~39.5 MJ/m³) ÷ 3.6. The calorific value varies slightly day to day and by region — your bill uses the exact figure for your supply, so this calculator's result is a close estimate, not an exact match to your bill.

Worked example

A metric meter reading that's gone up by 100 m³ converts to roughly 1,122 kWh. At the current price cap that's about £82.25 in usage cost, plus the standing charge for however many days the reading covers.

Current Ofgem Price Cap (Jul–Sep 2026)

	Unit rate	Standing charge
Gas	7.33p/kWh	29.04p/day
Electricity	26.11p/kWh	57.19p/day

Rates sourced from Ofgem — Energy Price Cap, current for Jul–Sep 2026. The meter conversion uses a typical reference calorific value — check your bill for the exact figure your supplier used, as it varies daily.

Frequently Asked Questions

How do I know if I have a metric or imperial meter?+

Metric meters (most modern ones) display in m³ and usually have "m³" printed on the dial or digital display. Older imperial meters display in hundreds of cubic feet and typically have a mechanical dial with no metric marking — if in doubt, your bill will state which units it converted from.

Why does the calorific value change?+

Natural gas composition varies slightly depending on its source, and National Grid publishes an updated calorific value for each network area daily. It typically sits between 39-40.5 MJ/m³, which is why this calculator's estimate may differ slightly from your exact bill. Read the full breakdown →

Is gas cheaper than electricity per kWh?+

Yes, significantly — at the current price cap, gas is 7.33p/kWh versus electricity at 26.11p/kWh, roughly a third of the cost. This is exactly why gas central heating and gas hobs are generally far cheaper to run than electric equivalents, heat pumps aside.