EPC Rating Estimator — Estimate Your Energy Performance Certificate Band

An Energy Performance Certificate (EPC) rates a property's energy efficiency on a scale from A (most efficient) to G (least efficient), with a SAP score from 1-100. EPCs are legally required when selling or letting a property in the UK. They are valid for 10 years and are produced by accredited Domestic Energy Assessors.

No. This is a simplified estimate based on SAP methodology principles. An official EPC can only be produced by an accredited Domestic Energy Assessor who physically inspects the property. Use this tool for a rough guide only — your actual EPC rating may differ significantly.

The current legal minimum to let a property in England and Wales is EPC band E (in force since April 2020). Under the Warm Homes Plan, confirmed by the government on 21 January 2026, all private rented homes must reach EPC band C by 1 October 2030 — this is now a single confirmed deadline for all tenancies, replacing the earlier proposed 2028 new-tenancy phasing, and is subject to a £10,000 per-property cost cap. The maximum penalty under the current rules is £5,000 per property; this rises to £30,000 per property under the 2030 regime.

The most effective improvements are: loft insulation (up to 270mm), cavity or solid wall insulation, upgrading to a condensing boiler or heat pump, installing double or triple glazing, and adding solar PV panels. Use our Loft Insulation Calculator, Cavity Wall Insulation Calculator, or Solar Panel Savings Estimator to plan specific upgrades.

SAP (Standard Assessment Procedure, used as RdSAP for existing homes) is the UK government's current methodology for assessing the energy performance of dwellings. It considers fabric heat loss, heating system efficiency, hot water, lighting, and renewable energy generation, and produces the single A–G band and 1–100 score this tool estimates. The full calculation is complex and is normally done using approved software by qualified assessors. Note that SAP/RdSAP is being replaced by the Home Energy Model (HEM) under a new four-metric EPC framework (fabric performance, heating system, smart readiness and energy cost), with launch targeted for around 2027 and a transition period running alongside the current system.

An official Energy Performance Certificate rating is calculated using the government's RdSAP (Reduced data Standard Assessment Procedure) for existing dwellings. An accredited Domestic Energy Assessor visits the property, records the building fabric (wall, roof and floor construction and insulation), windows and glazing, the main heating and hot water systems and controls, low-energy lighting and any renewables, then enters these into approved software. The software produces a SAP score from 1 to 100+ that maps to a band: A is 92-100, B 81-91, C 69-80, D 55-68, E 39-54, F 21-38 and G 1-20. This calculator follows the same input categories to give an indicative band, but it is not a substitute for the full RdSAP assessment.

This is an indicative estimator, not a calibrated RdSAP model. It uses the same headline factors a real assessment weighs — property type and age, floor area, wall and loft insulation, glazing, and heating and hot water systems — and maps a simplified score to the standard A-G bands. It is useful for comparing the likely effect of upgrades before you commission a survey, but the figure it returns can differ from an official EPC, which uses age-banded default U-values, measured dimensions, regional climate data and detailed system efficiencies. For a legally valid rating you must use an accredited Domestic Energy Assessor.

There is no government-set price for an EPC — gov.uk states you pay an accredited assessor a market rate. In practice a domestic EPC commonly costs roughly £60–£120, with flats at the lower end and large or complex houses higher, and a premium typical in London and the South East. Always compare quotes from accredited assessors. This online estimator is free and gives an indicative band, but it cannot replace the paid assessment a sale or letting legally requires.

The bands and SAP-based method are broadly the same across the UK, so the estimate is a reasonable guide anywhere. However, EPCs are a devolved matter: England, Wales and Northern Ireland share one accreditation and register system, while Scotland runs its own scheme where only assessors who are members of a Scottish Government 'Approved Organisation' can issue a valid certificate. Wherever you are, this tool gives an indicative band only — your official EPC must come from an accredited assessor under the scheme that applies to your nation.