NookPlanMeasure the room. Plan the rest.

Unfolded wall area

Paint quantity

Calculate the net paint area first, then add coats, product coverage, site loss, and package rounding.

  1. 1
    Gross wall area

    2 x (length + width) x height

  2. 2
    Net paint area

    Gross area - openings and excluded surfaces

  3. 3
    Theoretical volume

    Net area x coats / coverage per litre

  4. 4
    Prepared volume

    Theoretical volume x (1 + waste)

Use the product specification when available
Net paint area37.92 m²
Theoretical volume7.58 L
With waste8.34 L
Full packs2 packs

Result record

Save the estimate before package rounding hides it.

A purchase record should preserve gross wall area, deducted openings, coat count, exact product coverage, allowance, and pack size. If the order changes, that record shows whether the difference came from geometry or product assumptions.

  1. 01Replace the default coverage with the current product data sheet.
  2. 02Calculate primer and each colour as separate products.
  3. 03Record theoretical litres, prepared litres, and full packages separately.
Download recordRead the paint quantity field note

Why the defaults are only a starting point

Real coverage changes with product formulation, substrate absorption, texture, and application method. The 10 m² per litre and 10% waste defaults demonstrate the calculation. Check the actual product specification before buying.

How to handle openings

Deduct large windows, full-height fitted furniture, and surfaces receiving another finish. Small openings still create edges and touch-up work, so leaving them in the gross area can be a reasonable early allowance.

Calculate primer separately

This result is for finish paint. Primer may have a different coverage rate and coat count. Different colours should also be calculated separately because packaging and leftovers cannot be shared completely.

Read the complete paint quantity note

Site condition: Chalking, damp, mould, or widespread hollow patches require diagnosis before paint. More finish material will not repair a failing substrate.