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Answer three questions and get an estimated EPC rating, band and running cost for an existing home, every figure calculated in advance by our own RdSAP engine, the same methodology behind real certificates. Then fine-tune the heating, insulation, glazing and solar panels on the full explorer underneath.
The full explorer below starts from whatever the calculator hands it. Change the heating system, wall and loft insulation, glazing, hot water cylinder, solar panels and lighting, and watch the certificate respond. If the home sits below band C, the route button finds the cheapest priced combination of measures that clears it.
The estimates are not rules of thumb. We built thirty synthetic homes, five property types across six construction eras, each on the age-based assumptions an assessor's software applies when no better evidence exists, and ran every combination of home and improvement measures through our RdSAP engine in advance: 77,760 states in all. When you answer the three questions, the calculator looks up the state you described and reads off the rating, the modelled running cost behind it, and the environmental impact rating from the same calculation. Nothing is estimated on the fly, and nothing is fabricated.
The rating itself is a running-cost index from 1 to 100, banded A to G: the estimated annual cost of heating, hot water and lighting under standardised occupancy, adjusted for floor area. Because it prices every unit of energy, what heats the home dominates the result, which is why the calculator asks about heating and why the heating buttons carry such different numbers. Our EPC ratings explained guide walks through the whole story.
A real assessment measures your actual home and, crucially, records what can be evidenced. A filled cavity with no drill marks or paperwork must be recorded as unfilled. A boiler with a readable model plate is looked up in the product database rather than taken from an age table. An extension, a room in the roof, an unusual layout: all of it moves the number. Treat the estimate here as a map of which levers matter for a home like yours, not as your certificate.
If the home has been sold or let in the last ten years it probably already has a certificate. Every lodged EPC in England and Wales is free to view on the government's EPC register: search by postcode, and check the expiry date while you are there.
As accurate as its assumptions. Every figure this one shows is a real RdSAP calculation for a synthetic home of the type and age you pick, using the same age-based assumptions an assessor's software applies when nothing better is evidenced. What it cannot know is your actual home: its measured dimensions, its real boiler, and the paperwork that proves what is in the walls and loft. Those move real certificates by whole bands, in both directions.
You can estimate it, and that is what this page is for: learning which measures move a home like yours before spending anything. You cannot self-certify. An Energy Performance Certificate only exists once an accredited domestic energy assessor has surveyed the property and lodged the result on the national register.
Every certificate lodged in England and Wales is free to view on the government's EPC register at find-energy-certificate.service.gov.uk. Search by postcode. Certificates last ten years, so many homes have a valid one from a previous sale or tenancy.
Our domestic EPC surveys start from £59.95 plus VAT, booked online in minutes. The assessor visits, records the evidence, and the certificate is lodged on the national register.
Band E is the current legal minimum for rented homes in England and Wales. The government has confirmed its intention to raise the minimum to C for new tenancies from 2030, subject to legislation, with a cost cap and exemptions. The calculator marks the C line on every estimate.
Related reading: EPC ratings explained (the full guide behind this calculator), EPC rating C, EPC rating D, EPC rating E, and EPC changes explained.