A quantity should come with its working
Each calculator starts from measurements you enter and shows the assumptions that affect the result. It calculates a theoretical requirement, applies the selected waste allowance and rounds whole purchase units upward. Where useful, it also shows the unrounded amount so you can distinguish consumption from the quantity supplied by complete bags, cartons or cans.
The examples are hypothetical worked calculations, not records of completed projects. The present content and defaults are editorial drafts awaiting local specialist review before public indexing. No professional review, named reviewer or project approval is claimed unless it has actually been completed and recorded.
Blocks: net wall area divided by the installed face module
Add the wall areas, then deduct the included door and window openings. Divide the net area by the face length plus joint multiplied by the face height plus joint, using metres. Apply waste and round up to whole pieces. The initial values are a 40 × 20 cm face, a 1 cm joint and 5% waste.
Those face and joint values give approximately 11.61 blocks per square metre before waste, compared with 12.5 without joints. Confirm whether the supplier's dimensions are actual or nominal so a joint is not included twice. Thickness identifies the specified product; it does not enter this face-area count or establish a wall's performance.
Plaster: area and thickness converted into ingredients
Estimated dry volume equals area multiplied by thickness in metres and the dry-volume factor. Divide that volume into the stated cement and sand parts. Convert the cement share to a mass using the density input, divide by bag weight, add waste and round up. Apply waste to the sand volume separately.
The initial inputs are 2 cm thickness, a 1:4 volume ratio, a 1.30 dry-volume factor, cement density of 1,440 kg/m³, 50 kg bags and 5% waste. These are editable estimating assumptions, not an approved mix or independently verified local specification. Packaged ready-mixed plaster should instead follow the chosen product's consumption information.
Tiles: measured area converted to the actual carton
Add the floor and wall areas using the same product, apply the waste allowance, then divide by the actual carton coverage and round up. The starting carton value is 1.44 m². The 1.08 m² comparison in the guides illustrates why a tile dimension alone cannot define the quantity in a package.
The initial waste settings are 7% for straight and 10% for diagonal or staggered layouts, with an optional two-percentage-point increase for many cuts. Skirting cut from the same tile is estimated as complete tiles for usable strips and added before carton rounding. Saw kerf, finishing and practical reuse of offcuts require the installer's review.
Paint: litres per coat and complete packs
Net wall area equals perimeter multiplied by height, less openings. Add the ceiling when selected, multiply by coats, divide by square metres per litre per coat, and apply waste. The starting values are two coats, coverage of 8 m²/L per coat and 10% waste. Calculate each product and colour separately.
Default pack capacities are 3.6 and 18 litres, and both must be matched to the product. ‘Gallon’ refers to the supplier pack label here, not a universal volume conversion. The mixed-pack calculation covers the required litres with the entered sizes; it does not compare prices or promise the least expensive order. Preparation materials are excluded.
Units, input formats and rounding
Wall and room dimensions use metres. Block and tile dimensions and selected application thicknesses are labelled in centimetres; the calculation converts them as needed. Areas are square metres, sand volumes are cubic metres and paint volumes are litres. Review the unit beside a value before copying it from a supplier document.
The inputs accept Western and Arabic-Indic digits. A grouped value such as 1,200 is read as twelve hundred, while 3,5 is read as three point five. Empty or invalid values produce a validation message. Whole purchase quantities round upward while ignoring only tiny floating-point noise, so a numerical representation error does not add an extra unit.
Where the initial assumptions came from
The starting assumptions were taken from the project build guide dated 30 September 2026. That guide referenced calculators and product information from Hasbaty, Etimadco, Saudi Ceramics, Jazeera Paints, YouMats and supplier listings. Those references are not presented here as a current independent verification of every product, package or application value.
For an actual purchase, use the selected product's packaging and current technical information, measured site dimensions and approved project specification. Replace a default when those sources differ, and have the responsible contractor or engineer confirm the estimating basis. The tools estimate quantities; they do not design structures, supply live prices or approve construction work.
Sources and product references
These references explain the method or a specific product. Match the product and specification to your project before ordering.
- KFUPM: Measuring Masonry Work
Page 8 explains specified and nominal concrete block dimensions and the 12.5 blocks/m² module. This is a measurement reference, not a product approval.
- Saveto Saudi Arabia: Plaster Mix M
A manufacturer example of premixed plaster, showing why its product data should replace the separate cement-and-sand formula.
- Saudi Ceramics: FT 250-11690, 60 × 60 cm
The listed carton coverage for this product is 1.44 m².
- Saudi Ceramics: FT 250-12604, 60 × 60 cm
The listed carton coverage for this product is 1.08 m². Check the actual label before ordering.
- Jotun: Fenomastic My Home Rich Matt technical data, code 29600
Edition dated 6 June 2023, page 2: an example of theoretical spreading rate per coat. Use the current local sheet for your actual pack.
Prepared by the KSA Home Calc team. Content and defaults await professional review before launch. Updated: .