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Construction & Home
Free construction and home improvement calculators for homeowners, contractors, and DIY projects. Whether you are planning a driveway pour, painting a room, laying a floor, or putting up a fence, these tools handle the quantity math so you buy the right amount, not too little (an extra trip to the store) or too much (wasted money on returned materials).
What you can do here
Measure and plan materials
The Square Footage Calculator handles rectangular, triangular, circular, and irregular shapes, with an option to add multiple areas for a total. The Concrete Calculator computes cubic yards or meters for slabs, footings, columns, and walls, including a 10% wastage recommendation and conversion to bag count. The Paint Calculator estimates gallons or liters based on wall area, door and window deductions, and coat count.
Flooring, landscape, and exterior
The Flooring Calculator handles hardwood, laminate, vinyl, and tile with pattern-specific waste allowances for straight lay, diagonal, and herringbone installs. The Mulch and Gravel Calculator converts area and depth to cubic yards and bag count at common retail sizes. The Fence Calculator estimates posts, rails, and pickets for any perimeter and post spacing, including gate placements.
Where the wastage numbers come from
Every construction calculator here includes a recommended wastage percentage based on what the trade actually orders. Concrete: 10% for residential slabs, standard practice. Paint: 10% for a single room, 15% for multiple rooms with cutting in. Flooring: 5-15% depending on install pattern, higher for diagonal and herringbone. Fence materials: 10% for pickets, 5% for posts and rails. These numbers come from contractor estimation guides and trade standards, not invented.
These are estimates. Professional installers will adjust for specific site conditions (crooked walls, uneven ground, unusual cuts) that a calculator cannot see. Order against the calculator’s estimate, then verify on site before final purchase.
Frequently asked questions
How much concrete do I really need for a 10×20 slab?
Depends on depth. At 4 inches thick (standard for a patio), a 10×20 slab is 2.47 cubic yards, or 2.72 cubic yards including 10% waste. Use the Concrete Calculator to adjust for your specific dimensions and depth.
Do I need to subtract doors and windows from paint estimates?
The Paint Calculator does this for you when you enter door and window counts. As a rule of thumb, each standard door is 20 square feet and each standard window is 15 square feet of wall area deducted.