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Jointing Compound Calculator — Plasterboard Tape & Filler
Calculate how much jointing compound and tape you need for plasterboard flat joints and corners. Covers bedding, filling and finishing coats.
Total plasterboard area to be jointed
Default 10% — increase for complex layouts
Optional — for cost estimate
Default 2.4m — for corner calculations
Enable to calculate compound for wall-to-wall and wall-to-ceiling junctions
Ceiling-to-wall junction length (usually equals room perimeter)
4 for a rectangular room; count actual wall-to-wall internal corners
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How We Calculate This
This calculator estimates the jointing compound (filler) and tape required for plasterboard (drywall) installation. It uses your total area to work out the number of boards, then calculates joint lengths for both flat (board-to-board) and internal corner joints.
The 3-coat system
- Bedding coat (50mm wide): A thin layer of compound is applied along the joint and paper tape is pressed into it. Typical allowance ~0.15 kg/m.
- Filling coat (150mm wide): Once the bedding coat has set, a wider coat is applied over the tape to build up the joint level with the board face. Typical allowance ~0.35 kg/m.
- Finishing coat (250mm wide): A final thin coat is feathered out to blend the joint seamlessly into the surrounding board. Typical allowance ~0.25 kg/m.
These per-metre figures are typical trade allowances for a generic 3-coat system, not a manufacturer-published rate — actual usage varies with joint quality, board gap width and operator technique. Always cross-check the coverage on your chosen product’s data sheet (for example, Knauf Fill & Finish covers roughly 30 m² of board area per 20 kg).
Corner joints
Internal corners (where walls meet walls or walls meet ceilings) require paper tape folded along its centre crease. The calculator adds vertical corner joints (number of internal corners× ceiling height — default 4 for a rectangular room) plus the horizontal ceiling-to-wall perimeter.
Compound types
- Setting compound (powder):Mixed on site, sets chemically. More efficient coverage and faster recoat times. Brands: Gyproc EasiFill 60, Knauf Fill & Finish 60 Premium.
- Ready-mixed (tub):Pre-mixed and air-drying, convenient but higher moisture means ~10% more product needed and longer drying. Brands: Gyproc ProMix Lite, Knauf Fill & Finish (and the lighter Fill & Finish Light).
- Finishing compound: Lighter formula for the final coat only. Lower coverage rate but smoother finish. Often used over a setting compound base.
Frequently Asked Questions
The standard approach is three coats: a bedding coat (50mm wide) to embed the tape, a filling coat (150mm wide) to build up the joint, and a finishing coat (250mm wide) feathered to a smooth edge. Two coats can suffice for non-critical areas where skim plaster will be applied over the top.
Setting (powder) compounds (e.g. Gyproc EasiFill 60 or Knauf Fill & Finish 60 Premium) set chemically rather than by drying, so recoat time is independent of humidity. The "60" in the name is the working (pot) life, not the recoat interval: Gyproc EasiFill 60 has a set time of about 75 minutes and is recoatable after roughly 2 hours (its data sheet specifies a minimum of about 130–140 minutes). Ready-mixed, air-drying compounds (e.g. Gyproc ProMix Lite or Knauf Fill & Finish) need around 24 hours drying time between coats. Always check the manufacturer's data sheet.
Paper tape (e.g. Gyproc Joint Tape) is stronger, better for internal corners and gives a flatter finish — it is the industry standard for most flat and corner joints. Self-adhesive mesh tape is quicker to apply and works well with setting compounds on flat joints, but it is weaker and not recommended for internal corners or where movement is expected.
As a typical trade allowance (not a single published manufacturer figure), setting compound (powder) uses roughly 0.65-0.70 kg per linear metre of joint over three coats, ready-mixed compound around 0.80 kg/m due to higher moisture content, and a lighter finishing compound around 0.60 kg/m. Actual usage varies with joint quality, board gap width and operator experience, so always check the coverage stated on your chosen product's data sheet (for example, Knauf Fill & Finish covers about 30 m² of board area per 20 kg, the lightweight version about 45 m²).
The main UK brands are Gyproc (by Saint-Gobain), Knauf and Siniat. Gyproc EasiFill 60 is popular for bedding and filling coats, while Gyproc ProMix Lite or Knauf Ready Mixed are convenient for finishing. For best results, follow the current dry-lining code BS 8000-8:2023 (which superseded the withdrawn BS 8212:1995) and use the board manufacturer's recommended system — e.g. Gyproc tape with Gyproc compound on Gyproc boards.
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Last updated: April 2026
Verified against UK standards · estimates only, confirm with your supplier.