Free, accurate energy cost calculators for UK households. No sign-ups, no paywalls, no sponsored results.
This site is part of QuickSolve HQ, a small group of free UK tools. You can find the others at quicksolvehq.com.
Energy Calculator UK is built and maintained by the Energy Calculator UK team. We build free utility tools that help people make better decisions about household costs. Our other sites cover salary calculations, mortgage repayments, and word games.
We don't sell energy. We're not affiliated with any supplier, comparison site, or installer. The calculators exist because we wanted simple, accurate tools that show results instantly without asking for your email address or postcode first.
All electricity and gas rates come directly from Ofgem's published price cap announcements. We update the site within 48 hours of each quarterly cap change (January, April, July, October). The current rates used across the site reflect the October 2026 price cap (electricity carries no VAT this period, gas keeps 5%):
Appliance wattage figures come from manufacturer specifications and cross-referenced with data published by the Energy Saving Trust. Where an appliance has a range of wattages (for example, microwaves range from 600W to 1200W), we use the most common rating sold in the UK market.
The formula is straightforward: watts divided by 1,000 gives you kilowatts (kW). Multiply that by hours of use, then multiply by the unit rate in pounds. So a 2,000W heater running for 3 hours at 26.32p/kWh costs: 2 x 3 x £0.2632 = £1.58. We extend this to weekly, monthly, and annual costs based on how many days per week you use the appliance.
Monthly figures use 4.345 weeks (365 days / 12 months / 7 days). Annual figures multiply the daily cost by the number of usage days per year. These match the methodology used by the Energy Saving Trust and Ofgem's own example calculations.
Our solar estimates are based on published UK irradiance data. The average yield for a well-oriented system in the UK is approximately 850-1,050 kWh per installed kWp per year. We adjust for roof orientation (south-facing produces about 15% more than east/west) and geographic location (southern England gets roughly 10% more sunlight than Scotland).
Self-consumption rates of 40-50% without battery storage and 70-80% with battery storage come from monitoring data published by the Solar Energy UK (formerly Solar Trade Association) and independent studies from Sheffield Solar. System costs per kWp are based on average quotes reported by the Microgeneration Certification Scheme (MCS) installer database for Q2 2026.
We're an estimation tool. The figures we show are based on published rates and typical usage patterns. Your actual energy costs depend on your specific tariff, how you use your appliances, the efficiency of your home's insulation, and dozens of other factors. We don't provide energy advice, financial advice, or recommendations to buy or switch to any specific product or supplier.
If you need help paying your energy bills, contact your supplier about their hardship schemes or call the national Home Energy Scotland helpline (0808 808 2282) or the Simple Energy Advice service in England (0800 444 202).
Questions, corrections, or suggestions? Email us at hello@energycalculator.uk. We read every message and typically reply within 2 working days.