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Picture Rail Calculator

Calculate picture rail moulding lengths, mitre joints, adhesive and pin nails for any room. Deducts for door openings automatically.

Enter room perimeter directly

Toggle off to enter room length and width instead

Standard rectangular room = 4

Chimney breasts, bay windows etc.

Standard 762mm door deducted

Usually 300-500mm below ceiling

Length of moulding from your supplier

How We Calculate This

This calculator determines the total length of picture rail moulding needed for your room, the number of standard lengths to purchase, mitre joint count, adhesive and pin nails.

Rail length

Total rail = Room perimeter - Door openings. Each standard UK door opening is deducted at 762mm. The rail stops at the edge of the door architrave.

Lengths to buy

Lengths = ceil(Total rail / Standard length). Picture rail typically comes in 2.4m or 3.0m lengths from UK timber merchants. Buy one or two extra lengths to allow for mitre waste and any mistakes.

Mitre joints

Each corner requires a mitre joint. Internal corners can be coped for a better fit on walls that aren't perfectly square. External corners (chimney breasts, bay windows) must be mitred at 45 degrees.

Fixings

  • Grab adhesive: ~1 tube per 8m of rail
  • Pin nails: 1 per 300mm, used to hold rail while adhesive sets

Standard heights

Picture rail is installed between 1.8m and 2.1m from the floor, typically 300-500mm below the ceiling. In a standard 2.4m ceiling room, 2.0m from the floor is most common.

Frequently Asked Questions

Last updated: February 2026

All calculations are estimates. Verify with your supplier.