Draught-Proofing Calculator — Materials & Savings Estimate

This calculator estimates the draught-proofing materials you need by calculating the total perimeter of doors, windows and other openings that need sealing, then working out how many rolls of draught strip to buy.

Perimeter estimates used

• External door: ~6.0m perimeter (including threshold)
• Sash window: ~6.5m (two sashes, each with sealing perimeter)
• Casement window: ~4.0m perimeter (typical opening casement)
• Loft hatch: ~3.6m perimeter

Additional products

• Chimney balloon/sheep: One per unused chimney to prevent heat escaping
• Letterbox cover: A brush-type internal cover to reduce draughts through the letterbox

Energy savings

Savings are indicative figures from the Energy Saving Trust: around £85 a year (Great Britain) for draught-proofing doors, windows and floors, plus a separate ~£60 a year for each unused chimney you seal. These are national averages — your real saving depends on how draughty your home is and your energy tariff. Draught-proofing costs relatively little but can make a noticeable difference to comfort and heating bills, and is often recommended as a first step in improving home energy efficiency.