What is an EPC rating?

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.

Is this an official EPC?

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.

What EPC rating do I need to let a property?

Since April 2020, all rental properties in England and Wales must have a minimum EPC rating of E. The government has proposed raising this to C for new tenancies from 2025 (though this timeline has been subject to change). Landlords who fail to comply can face fines of up to £5,000.

How can I improve my EPC rating?

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 (/insulation/loft-insulation-calculator/), cavity wall insulation calculator (/insulation/cavity-wall-insulation-calculator/), or solar panel savings estimator (/insulation/solar-panel-savings-estimator/) to plan specific upgrades.

What is the SAP methodology?

SAP (Standard Assessment Procedure) is the UK government's methodology for assessing the energy performance of dwellings. It considers fabric heat loss, heating system efficiency, hot water, lighting, and renewable energy generation. The full SAP calculation is complex and is normally done using approved software by qualified assessors.

EPC Rating Estimator \u2014 Estimate Your Energy Performance Certificate Band

Get a simplified estimate of your property's EPC rating based on construction, insulation, glazing and heating. Not an official assessment.

Disclaimer: This is a simplified estimate only. An official EPC must be produced by an accredited Domestic Energy Assessor. Your actual rating may differ.

Property Details

Property Type

Affects calculation based on property characteristics

Property Age

Select the property age for your calculation

Total Floor Area

All floors combined

Insulation & Glazing

Wall Insulation

Select the wall insulation for your calculation

Loft Insulation

Select the loft insulation for your calculation

Glazing Type

Affects U-value and energy performance

Heating & Hot Water

Main Heating System

System type affects efficiency and output

Hot Water System

Select the hot water system for your calculation

How We Calculate This

This estimator uses a simplified version of SAP (Standard Assessment Procedure) methodology principles to estimate your property's EPC band. It considers the key factors that influence energy efficiency: property type, age, insulation levels, glazing and heating system.

How it works

Each property characteristic contributes positively or negatively to a baseline score. The total score is mapped to an EPC band using the standard SAP banding thresholds:

Band A: 92-100 (very energy efficient)
Band B: 81-91
Band C: 69-80
Band D: 55-68
Band E: 39-54
Band F: 21-38
Band G: 1-20 (very energy inefficient)

Important disclaimer

This is a rough estimate only and should not be relied upon for legal compliance, property transactions or planning decisions. An official EPC requires a physical inspection by an accredited Domestic Energy Assessor using approved SAP software. Your actual rating may differ from this estimate.

Frequently Asked Questions

Related Calculators

U-Value Calculator

Calculate the U-value of wall, floor and roof constructions.

Insulation Thickness Calculator

Determine the insulation thickness needed to meet UK Building Regulations.

Heat Loss Calculator

Calculate room-by-room heat loss for heating system sizing.

Cavity Wall Insulation Calculator

Estimate cavity wall insulation quantities and potential savings.

Loft Insulation Calculator

Calculate loft insulation rolls needed for your loft area.

Last updated: February 2026

All calculations are estimates. Verify with your supplier.