UK Gas Bill Calculator — Calculate Cost from kWh or Meter Readings

Your UK gas bill is calculated by multiplying your gas usage (in kWh) by the unit rate, then adding the standing charge for the billing period. Usage is measured in cubic metres or cubic feet by your meter, then converted to kWh using the calorific value (about 39.5 MJ/m³) and volume correction factor (1.02264). Finally, 5% VAT is added to domestic gas bills.

The standing charge is a daily fixed fee charged by your energy supplier regardless of how much gas you use. As of the current Ofgem Energy Price Cap (Apr–Jun 2026), the GB average standing charge is 29.09p per day. It covers the cost of maintaining the gas network, meter reading, and billing services.

The UK formula, set by the Gas (Calculation of Thermal Energy) Regulations 1996, is: kWh = (volume in m³) × calorific value × 1.02264 ÷ 3.6. If your meter reads in m³ (metric — most modern meters), use the volume difference directly. If your meter reads in hundreds of cubic feet (hcf, most imperial meters), multiply the units difference by 2.832 first to convert to m³. Your bill will show the calorific value used for that period — typically around 39.5 MJ/m³, and always within the regulated range of 38 to 41 MJ/m³.

As of the current Ofgem Energy Price Cap (Apr–Jun 2026), the GB average gas unit rate for customers paying by Direct Debit is 5.74p per kWh, with a daily standing charge of 29.09p. These figures are already VAT-inclusive at 5%. Your exact rate depends on your region (14 GB regions), supplier, tariff and payment method — Prepayment customers pay a lower unit rate but the same standing charge in most regions; Standard Credit customers pay the highest rates. Check your most recent bill or your supplier's tariff information page for your exact figures.

High gas bills can result from: increased usage during cold weather, inefficient boiler (consider getting a gas rate calculation done), poor insulation, incorrect meter readings, or being on a more expensive tariff. Use this calculator with your actual meter readings to verify your bill is correct.

Ofgem's official "medium" typical domestic consumption value (TDCV) for gas is 11,500 kWh per year (updated from 12,000 in October 2023). Low-use households (1-bed flat, 1–2 people) average 7,500 kWh; high-use households (4+ bedroom, 4–5 people) average 17,000 kWh. Ofgem consulted in March 2026 on reducing these further — proposing a new medium of 9,500 kWh — but the 2023 values remain the benchmark throughout 2026.

The Ofgem Energy Price Cap is the maximum per-unit rate and daily standing charge that an energy supplier can charge you if you're on a standard variable (default) tariff. It's updated every three months and covers gas and electricity separately. For the cap period Apr–Jun 2026, the GB-average gas rates are 5.74p/kWh and 29.09p/day (Direct Debit, VAT inclusive). The cap does not cap your bill — it caps the rate — so your total bill still depends on how much you use. For context, Ofgem's typical dual-fuel annual bill (gas plus electricity, medium consumption) for Apr–Jun 2026 is £1,641.

To reduce your UK gas bill: 1) Improve home insulation (loft, walls, windows), 2) Service your boiler annually to maintain efficiency, 3) Install a smart thermostat, 4) Lower your thermostat by 1°C (saves ~10% on heating), 5) Bleed radiators regularly, 6) Switch to a better tariff or supplier, 7) Consider upgrading to a more efficient boiler.

This gas bill calculator UK tool provides estimates based on the Ofgem Energy Price Cap rates. Actual bills may vary slightly based on your specific supplier, regional variations, and exact meter readings. For precise figures, always check your energy statement or contact your supplier directly. Please rely on a professional, accredited Gas Safe engineer and accredited tools for all measuring.

Gross calorific value (GCV) measures total energy content of gas including water vapour. Net calorific value (NCV) excludes energy in water vapour and is typically ~10% lower. UK gas bills use the gross value (about 39.5 MJ/m³). Modern condensing boilers recover some of this extra heat, making them more efficient.