Loft Conversion Calculators
A loft conversion involves multiple trades and a wide range of materials. We've curated all the calculators you'll need for planning and estimating a loft conversion project, organised by trade stage. Use these to estimate materials before getting quotes, or to check quantities against a builder's pricing.
Planning
Insulation
Plastering & Boarding
Plasterboard Calculator
Calculate boards for walls, ceiling (under rafters), and dormer cheeks.
Skim Coat Calculator
Multi-finish plaster needed for skimming all plasterboard surfaces.
Plaster Bead Calculator
Angle beads for dormer windows, riser walls, and stud corners.
Dry Lining Calculator
Complete dry lining material list including tape and jointing compound.
Electrics
Cable Sizing Calculator
Size cables for new lighting, socket, and smoke detector circuits.
Lighting Layout Calculator
Plan downlight and lighting positions for the new loft room.
Socket Spacing Calculator
Plan socket positions and quantities for the loft space.
Cable Length Calculator
Estimate total cable runs from the consumer unit to the loft.
Flooring
Floor Joist Calculator
Check joist sizing if strengthening the existing loft floor.
Laminate Flooring Calculator
Calculate laminate or engineered flooring packs for the loft room.
Carpet Calculator
Carpet and underlay quantities for the loft room and staircase.
Skirting Board Calculator
Skirting board lengths for the finished loft room.
Roofing (if adding a dormer)
All calculators are free to use with no signup required. Results are estimates — always verify quantities on site and consult qualified professionals for structural, electrical, and building regulations compliance.