The FRELUX Paint Calculator uses a room-based methodology to estimate how much paint you need. Enter your room dimensions, wall height, doors, and windows, and the calculator determines paintable area, applies admin-configured coverage rates, and recommends purchase quantities in 20-litre buckets.
How the FRELUX Paint Methodology Works
FRELUX calculates paint quantity using a room-by-room approach rather than a generic square-metre input. The process is:
Measure the room: enter length, width, and wall height (in feet by default, with optional metric support).
Deduct openings: doors and windows are subtracted from the total wall area.
Apply coverage rate: the admin-configured coverage rate (m² per litre per coat) determines how much paint each surface needs. This rate is managed in the database, not hardcoded.
Surface condition adjustment: rough, textured, or new plaster surfaces absorb more paint. FRELUX applies adjustment factors (e.g. rough surfaces reduce effective coverage by approximately 25%).
Colour condition logic: dark colours over light surfaces may require extra coats or primer. FRELUX flags this with warnings and adjusts minimum coats.
Calculate coats: 2 coats is the FRELUX standard. The calculator multiplies single-coat quantity by the number of coats.
Recommend purchase quantities: paint is sold in 20-litre buckets. The calculator shows both theoretical litres and practical purchase quantities (buckets to buy).
Inputs Required
Room length and width (feet or metres)
Wall height (feet or metres; 8 ft / 2.44 m is the FRELUX standard)
Number and dimensions of doors (default: 0.9m × 2.1m)
Number and dimensions of windows (default: 1.2m × 1.2m)
Number of coats (2 is standard)
Paint type and quality (affects admin-configured coverage rate)
Surface condition (smooth, textured, rough, or new plaster)
Colour condition (same/light, dark over light, light over dark, or new/unpainted)
What the Calculator Produces
Total paintable wall area in m²
Theoretical paint quantity in litres
Practical purchase quantity (number of 20-litre buckets)
Primer/sealer recommendation where applicable
Height warning for non-standard wall heights above 8 ft
Colour condition warnings (e.g. extra coats needed for dark over light)
Market Context
FRELUX coverage rates and product sizes are calibrated for real market products. Material prices are admin-configurable and can be adjusted to match your local supplier. The standard purchase unit is the 20-litre bucket, which is the most common container size in many markets.
Frequently Asked Questions
How does the FRELUX paint calculator differ from a generic area-based calculator?
FRELUX uses a room-based approach: you enter room dimensions (not raw m²), and the calculator handles all the area math internally. Coverage rates are admin-configured from the database, not assumed. Surface condition, colour condition, and wall height all affect the final quantity.
Why does the calculator recommend 20-litre buckets?
20-litre buckets are a standard purchase unit in many paint markets. The calculator shows both theoretical litres needed and the practical number of buckets to buy, so you know exactly what to purchase.
Do I need primer?
FRELUX recommends primer for new/unpainted surfaces and when painting light colours over dark surfaces. The calculator flags these conditions automatically based on your colour condition selection.
Can I calculate paint for exterior walls?
Yes. Select the exterior project type in the calculator. Exterior surfaces may have different coverage rates and surface conditions.
Disclaimer: FRELUX estimates are for planning purposes. Actual paint consumption varies with surface texture, application method, and painter technique. Always verify with your painter or supplier.