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Buying Guide

Best Letterbox Draught Excluders UK 2026

Updated June 2026

Your letterbox is a direct hole to the outside. On a windy day, cold air pours through it like a mini wind tunnel — you can feel it from across the hallway. Yet most UK homeowners never think to seal it. A letterbox draught excluder costs £8–£20 and takes 5 minutes to fit. It is one of the cheapest and most effective draught-proofing fixes for any UK front door.

Quick answer

Our top pick: UAP MailPlate (full internal cover)

£15–£22 on Amazon

Blocks 100% of draughts. Best budget alternative: Stormguard brush cover (£8–£14). Both fit standard UK letterbox sizes.

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How much heat does a letterbox lose?

The Energy Saving Trust estimates that draughts (including letterboxes) cost the average UK home around £60 a year in wasted heat. A standard UK letterbox slot is approximately 250mm × 38mm — a gap of nearly 100cm² straight to the outside.

On a windy winter day, cold air flows through this gap at significant volume, dropping the hallway temperature by 2–3°C. Sealing it is one of the highest-impact, lowest-cost draught-proofing jobs in your home.

3 types of letterbox draught excluder

Type 1

Brush covers (budget)

  • Internal or external brush strips fitted over the slot
  • Post pushes through the bristles
  • Blocks 70–80% of draughts
  • Cheapest option, easiest to fit

Type 2 — Best

Full cover plates

  • Solid plate covers the entire letterbox from inside
  • Post pushes through a hinged flap
  • Blocks 100% of draughts
  • More expensive, slightly stiffer delivery

Type 3

Secondary flap/seal

  • Additional rubber or magnetic flap behind the existing letterbox
  • Works alongside the existing cover
  • DIY option for maximum sealing

The products we recommend

#1 Best Overall — Full Cover

UAP MailPlate Telescopic Letterbox Cover

4.3
£15–£225% commission

Blocks 100% of draughts — not just reduces them like brush covers. The telescopic design adjusts to fit any UK door thickness (40–80mm). Screws on from inside over your existing letterbox. 3,430+ reviews on Amazon. Post still gets delivered through a hinged flap.

Pros

  • Blocks 100% of draughts
  • Telescopic fit for any door (40–80mm)
  • 3,430+ Amazon reviews
  • Easy to install
  • Post still gets through

Cons

  • Requires 4 screws (ask landlord)
  • Post delivery slightly stiffer
  • Plastic, not metal

Who it's for: Homeowners wanting maximum draught protection

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#2 Best Budget — Brush

Stormguard External Letterbox Cover with Brush

4.2
£8–£145% commission

UK brand since 1810. Brush bristles cover the letterbox slot, blocking wind while letting post through easily. Fits standard UK letterbox openings (338mm × 78mm). Works on internal or external mounting.

Pros

  • UK brand since 1810
  • Cheapest effective option
  • Brush lets post through easily
  • Internal or external fitting

Cons

  • Only blocks 70–80% of draughts
  • Plastic frame
  • May need trimming for non-standard sizes

Who it's for: Budget buyers and renters (lighter installation)

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#3 Draught-proof the whole door

The letterbox is just one source of door draughts. To stop cold air properly, seal the bottom of the door and the frame too.

How to measure your letterbox

Measure before you buy

Measure the letterbox slot width and height from inside the door. Standard UK letterboxes are approximately 250mm wide × 38mm high, but older doors may vary. The UAP MailPlate fits any standard size.

If your letterbox is non-standard, measure before ordering and double-check the product dimensions on the Amazon listing.

Tip

Combine for best results

A letterbox cover alone won't stop every door draught. Pair it with an under-door brush and a strip of foam around the frame for a complete seal — total cost under £40 and saves an estimated £60/year on heating.

Frequently asked questions

Bundle

The Front Door Draught-Proofing Kit — Under £45

Total:approximately £40
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