Verify measurements, product specifications, local requirements, and supplier order quantities before buying materials or starting work.
Concrete slab
Volume = length × width × thickness
The tool assumes a uniform rectangular slab. It converts dimensions to consistent units and applies the entered extra allowance once. Estimated cost uses the resulting quantity multiplied by your price per cubic yard or cubic metre. It does not determine safe thickness, reinforcement, strength, or foundation design.
Paint
Net wall area = 2 × (length + width) × height − openingsPaint quantity = (net wall area + optional ceiling) × coats ÷ coverage
The tool assumes four equal-height walls. Opening area is the combined area of doors and windows, not their count. Ceiling area is length × width and uses the same paint, coverage, and coat count. Primer, trim, extra allowance, and rounding to paint-container sizes are not included. Use the manufacturer’s single-coat coverage value.
Gravel
Volume = length × width × depth × (1 + allowance ÷ 100)Weight = volume × bulk density
Density varies with material, grading, moisture, and compaction. The sample density is editable and should be replaced with a supplier’s value. Pricing uses metric tonnes in metric mode and US short tons in imperial mode. This does not specify a compacted depth or suitable material for your project.
Mulch
Required volume = length × width × depth × (1 + allowance ÷ 100)Bags = required volume ÷ bag volume, rounded up
Cost uses whole bags, not the unrounded volume. Enter the actual packaged bag volume. The sample depth is not plant-care advice.
Flooring
Required area = length × width × (1 + waste ÷ 100)Boxes = required area ÷ coverage per box, rounded up
Cost uses whole boxes. The displayed purchased area may exceed the required area. Patterns, cutting, damage, and product instructions can change the waste allowance. Underlay, adhesive, trim, and installation are excluded.
Square footage
Total area = sum of (length × width) for each rectangle
Enter non-overlapping rectangular areas. Divide irregular rooms into rectangles without counting shared areas twice. This is not a certified survey or a determination of legally reportable floor area.
Units and rounding
- 1 foot = 0.3048 metres; 1 inch = 2.54 centimetres.
- 1 cubic yard = 27 cubic feet = 0.764554857984 cubic metres.
- 1 US gallon = 3.785411784 litres. UK imperial gallons are not used.
- 1 pound = 0.45359237 kilograms.
- 1 metric tonne = 1,000 kilograms; 1 US short ton = 2,000 pounds.
Most quantities are displayed to a maximum of three decimal places and costs to two decimal places. Calculations generally retain greater precision internally. Bag and box counts use upward whole-package rounding with a small numerical-precision adjustment to avoid extra packages caused only by floating-point noise. Displayed tiny quantities can round to zero; inspect your inputs before ordering.
Prices and currency conversion
The supplier price currency describes the price you enter. Selecting another supplier currency reinterprets that entered price; it does not exchange money. Use the separate “Convert estimate to” control to convert the calculated cost.
Conversion uses daily ECB reference rates delivered through Frankfurter. The displayed rate date may precede today, particularly on weekends or holidays. Successfully retrieved rates are reused in page memory for up to one hour. The converter shows the rate date, flags rates more than seven days old, and offers a retry if retrieval fails.
Conversion is based on the displayed, rounded material cost. It excludes bank spreads and exchange fees, is not a tradable quote, and does not estimate a product’s local price or availability in another country.
What estimates exclude
Unless explicitly stated otherwise, estimates exclude taxes, delivery, labour, permits, equipment, supplier minimum orders, and project-specific professional services. Sample values and allowances are not universal recommendations.
Limitations and corrections
We aim for useful and accurate calculations, but software, source rates, and user inputs can contain errors. No guarantee is made that an estimate is complete or suitable for a particular project. Do not use these tools as a substitute for engineering design, professional measurement, product instructions, or local building requirements. Nothing here limits rights that cannot lawfully be excluded.
Report calculation issues to bhant11@gmail.com. Our Contact page explains what information helps us investigate.