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Global Home, Construction & DIY Calculators
Thirty free, instant and honest calculators — metric first, imperial one tap away. Every tool shows its assumptions, its waste allowance and the plain-English maths behind the number. Pick the project you’re working on, or start from a project plan.
Concrete & Building
Concrete, Masonry & Structure
- Concrete Slab & Footing Concrete & Building Cubic metres and yards, 25 kg / 80 lb bag counts, #4 rebar requirements — including a waste factor. Built for patios, driveways, footings, shed pads and walkways.
- Gravel & Aggregates Concrete & Building Volume and mass for any sub-base or fill: cubic metres and yards, tonnes and US tons, bulk-bag counts — with typical densities for crushed stone, pea gravel and sand.
- Brick & Block Quantity Concrete & Building Units per m² from any brick or block size and joint, single or double skin — plus the mortar volume the wall will consume.
- Mortar Mix & Ratios Concrete & Building Mortar volume plus a cement:sand ratio in — cement in 25 kg bags and sand in kg and m³ out, using the standard dry-volume factor.
- Render & Plaster Concrete & Building Wall area, thickness and coats in — cement and sand quantities out for sand-cement render and base-coat plaster, with openings deducted.
- Stair Rise & Run Concrete & Building Total floor-to-floor rise in — riser count, actual riser and tread, total run, stair angle and the 2R + T comfort check out.
Garden & Outdoor
Garden & Outdoor
- Mulch & Topsoil Bulk Garden & Outdoor Cubic metres, cubic yards, litres and bag counts for any bed shape — rectangle or circle — with common retail bag sizes built in.
- Deck Lumber Garden & Outdoor Footprint and framing in — joists, beam, posts and deck boards out, checked against the IRC span tables, fasteners counted.
- Paver Quantity Garden & Outdoor Paver count from area, paver size, joint gap and waste — plus the bedding sand volume, with typical layouts pre-set.
- Retaining Wall Blocks Garden & Outdoor Courses, blocks per course and total block count from wall dimensions — with the drainage and engineering warnings that matter.
- Fence Post & Rail Garden & Outdoor Posts, rail length, board count and post-hole concrete from a fence run — spacing, hole size and board dimensions all editable.
- Raised Bed Soil Garden & Outdoor Soil volume in litres for any bed size — and the bag count at 40, 50 or 60 L, across as many beds as you’re building.
Roofing & Solar
Roofing & Solar
- Roofing Materials Roofing & Solar Footprint and pitch to a full shingle order: squares, bundles, underlayment rolls, ridge caps, drip edge, starter and nails — waste included.
- Gutter & Downpipe Roofing & Solar Eave run, roof width and pitch in — gutter length, effective catchment area, downpipe count and bracket spacing out.
- Solar Panel System Sizing Roofing & Solar Panel count from roof area, system size in kW, and daily and annual kWh production — with sun-hours and efficiency losses built in.
- Solar Battery Sizing Roofing & Solar Daily usage and backup days in — bank capacity in kWh and Ah at 12, 24 or 48 V out, with depth of discharge and inverter efficiency accounted for.
Painting & Walls
Painting & Walls
- Paint & Primer Coverage Painting & Walls Auto-deducts doors and windows, applies the coat multiplier, returns litres and gallons for walls and ceiling — coverage per can is editable.
- Drywall Sheet & Screws Painting & Walls Estimates 4×8 or 4×12 sheets from room perimeter, plus joint compound buckets, tape rolls and screw counts.
- Wallpaper Rolls Painting & Walls The strips method done properly: roll width, wall height and pattern repeat in — strips, strips per roll and total rolls out.
Flooring
Flooring & Tiles
- Tile Layout & Mortar Flooring Dynamic Canvas visualizer of the tile grid, plus thinset and grout quantities — in 50 lb or 20 kg bags — for any tile size and joint.
- Flooring Quantity Flooring Room area with layout-specific waste in — packs of laminate, vinyl or plank out, from the m²-per-box figure on the label.
Pools & Water
Pools & Water
- Pool Volume Pools & Water Rectangular or round, with the average-depth method — cubic metres, litres, US gallons, fill time and water mass.
- Pond Liner Size Pools & Water The liner formula done for you: length + 2 × depth + 2 × overlap, per dimension — plus underlay area.
- Pond Volume & Pump Flow Pools & Water Pond volume in litres and UK gallons, and the pump flow your filter needs from a chosen turnover time.
Home Maintenance
Home Systems & Maintenance
- Water Heater Sizing Home Maintenance Peak-hour worksheet to First Hour Rating for tanks, and true flow at winter temperature rise for tankless — with the electric service check built in.
- Attic Insulation Home Maintenance Climate zone and existing depth in, the R-value gap out — settled depth, volume and bags to blow, or batt layers to buy.
- Pipe Volume Home Maintenance Material and nominal size in, the true bore out — litres and gallons held, water mass, the hot-water wait and flow velocity.
- Rainwater Collection Home Maintenance Roof footprint and rainfall in — litres per millimetre of rain, per event, and per year, with collection efficiency accounted for.
- Electrical Service Load Home Maintenance NEC Article 220, both methods: floor area and nameplates in, calculated amps out — demand factors and a suggested service size (North-American reference).
Garage & Workshop
Garage & Workshop
Roadmap
How This Library Grows
Thirty calculators are live, each with its maths documented and tested against worked examples. The library grows the same way it always has: a tool ships only when its numbers test clean and a field guide exists to explain them. The project hubs are the map of what’s coming next — each one names the tools its project still wants.
Also in the library: fifty field guides — from concrete curing to how homes are built around the world — each paired with the calculator that does its arithmetic.