Paint Calculator

To calculate paint quantities, first measure the total wall area in square metres: calculate height multiplied by width for each wall, then subtract the area of doors (approximately 1.8m2 each) and windows (approximately 1.2m2 each). Divide the net area by the coverage rate printed on your paint can — standard interior paint typically covers 10-14m2 per litre. Add 10-15% atu for waste, second coats, and touch-ups. For example, a room with 40m2 of paintable wall area using a 12m2/L paint needs about 3.3 litres for one coat, or 6.6 litres for two coats. Always buy slightly more than calculated, as colour matching later can be difficult. Ceiling and trim paints have different coverage rates — check the product data sheet. Source: Resene resene.co.nz; Dulux dulux.co.nz.

Primer, undercoat, and topcoat serve distinct roles in a painting system. A primer is applied first to seal porous surfaces (bare timber, new plaster, or repaired areas), improve adhesion, and prevent stains from bleeding through. An undercoat is applied after priming (or directly on previously painted surfaces) to build up the paint film thickness, fill minor imperfections, and create a uniform base colour for the topcoat. The topcoat is the final decorative layer providing the desired colour, sheen level, and durability — in NZ, common topcoats include flat, low-sheen, semi-gloss, and gloss finishes. Some NZ products combine primer and undercoat functions. For exterior painting in the NZ climate, using a quality primer system significantly extends paint life. Source: Resene resene.co.nz; Dulux dulux.co.nz.

Paint prices in New Zealand vary by product type and quality tier. Budget interior paints start from around $15-25 per litre and are suitable for low-traffic areas. Mid-range interior paints from brands such as Resene and Dulux cost $30-50 per litre and offer better coverage, durability, and washability. Premium interior paints, including low-VOC and speciality formulations, range from $60-90 per litre. Exterior paints generally cost more due to their enhanced weather resistance: expect to pay $40-70 per litre for quality exterior products. Trade accounts at Resene ColorShops or Dulux Trade centres offer discounts of 10-30% for professional painters and builders. Prices vary by store and can change seasonally. Source: Resene resene.co.nz; Dulux dulux.co.nz.

The number of paint coats needed depends on the surface condition and colour change. New or bare surfaces typically require a primer or sealer coat plus two topcoats for full coverage and durability. When changing from a dark to a light colour, two topcoats are usually necessary to achieve even coverage and hide the previous colour. Repainting in the same or similar colour may only need one topcoat if the existing surface is in good condition. High-sheen finishes (gloss, semi-gloss) show surface imperfections more readily than flat or low-sheen paints, so better surface preparation reduces the number of remedial coats needed. In high-moisture NZ areas (bathrooms, kitchens), use moisture-resistant paint and ensure adequate coats for durability. Source: Resene resene.co.nz; Dulux dulux.co.nz.