Use our simple guide below to calculate what size cast iron radiator you need. 

Find the volume of the room by multiplying the width x length x height in metres. For living and dining rooms multiply by 50. For bedrooms multiply by 40. For halls and kitchens multiply by 30. For bathrooms multiply by 90.

For rooms facing North add 15%. For French windows add 20%. For double glazing deduct 10%. For a very cold climate such as windy high altitude locations, add 10%.

This will give you the required heat output in Watts. To convert heat outputs to BTU multiply the Watts figure by 3.41.

If you are unsure or need further help feel free to contact our sales department on 01748 821500 or e-mail us at enquiries@periodhousestore.co.uk

Cast iron radiator sizing figures quoted here are given in good faith and are true to the best of our knowledge. Actual heat requirements for a given room can vary.