What size do I need?

Answer a few quick questions about your room and we’ll work out the heat output you need, then show you radiators that will do the job.

The room Room type

Measurements in metres feet

Length Width Height

Walls & windows Outside walls in this room Wall construction

Number of windows Glazing

French, patio or bi-fold doors

Above & below

Above the room Below the room

Your heating How is the radiator heated?

Number of radiators Style

Wall space available (optional)

0BTU/hr

0 watts

Uses the standard room-volume method used across the UK radiator industry. If you’re between sizes, go for the bigger radiator. Need a hand? Email us.

Important: guidance only

This calculator gives an estimate to help you shortlist products. It is not a heat loss calculation, survey or system design, and Heat-In & Cool-In Ltd accepts no design responsibility or liability for the results or for the suitability of any product chosen using them.

The heat a room actually needs depends on things we can’t assess online, including your property’s construction, insulation, glazing, draughts, room use and, for radiators, your system’s flow temperature. Before buying, we recommend you have the heat requirement confirmed by a qualified heating or air conditioning engineer, particularly for heat pump, low-temperature or new systems.

Choosing the right product remains your responsibility. Our normal returns policy applies to all orders.

What size do I need?

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