9 calculators · exact material counts · imperial or metric
Know exactly how much to buy before you go.
Every calculator here does the same job a good contractor's estimate does: real coverage rates, sensible waste allowances, and quantities rounded up to what you'd actually purchase — by the bag, box, roll or bundle. Nothing is uploaded; it all runs on this page.
Imperial + metricWaste factors built inBuy-quantities, not raw math
Interior
Yard & garden
Structures
Reference
Why "just measure the area" gets the order wrong
Almost every material estimate fails the same way: someone measures the square footage, buys exactly that much, and comes up short. Real jobs lose material to cuts, breakage, pattern matching and rounding to whatever size the store actually sells — a box of 10 tiles, an 80lb bag, a 33ft roll. The gap between the raw number and the number you actually purchase is where every return trip to the store comes from.
What each calculator actually does
Computes the raw area, length or volume from your measurements
Applies an industry-standard waste allowance for that material and job type
Converts to the units the material is actually sold in — bags, boxes, rolls, tons
Rounds up to a whole purchasable unit, because stores don't sell 2.3 bags
Imperial and metric, properly
Every calculator has a unit switch in the top corner. Switching doesn't just relabel the fields — it converts the values so a measurement taken in metres stays a measurement in metres all the way through, and the material quantities (litres of paint, kilograms of seed, cubic metres of concrete) come out in the units you'd actually buy locally.
🎨 Calculator 1 of 9
Paint Calculator
Enter the room's wall dimensions and openings — get gallons or litres to buy, by coat.
Inputs
ft
ft
count
count
ft
ft
sqft / gal
Standard interior paint: ~350 sqft per gallon (~8.6 sqm per litre) per coat
◻️ Calculator 2 of 9
Tile Calculator
Enter the room and tile size — get tiles and boxes to buy, with waste allowance.
Inputs
ft
ft
in
in
tiles
$
🧻 Calculator 3 of 9
Wallpaper Calculator
Enter wall dimensions and roll size — get rolls to buy, accounting for pattern repeat.
Inputs
ft
ft
count
count
in
ft
in
0 = plain or random match
%
$
🌱 Calculator 4 of 9
Lawn Seed Calculator
Enter the lawn area and seeding rate — get seed weight and bags to buy.
Inputs
ft
ft
lb
$
%
🍂 Calculator 5 of 9
Mulch Calculator
Enter bed area and depth — get cubic yards (or metres) and bags to buy.
Inputs
ft
ft
cu ft
$
$ / cu yd
%
🚧 Calculator 6 of 9
Fence Calculator
Enter fence run and spacing — get posts, rails and pickets to buy.
Inputs
ft
count
rows
in
in
%
$
$
$
🪵 Calculator 7 of 9
Deck Calculator
Enter deck dimensions and board size — get boards, joists and footings to buy.
Inputs
ft
ft
in
ft
ft
%
$
$
$
🪨 Calculator 8 of 9
Gravel Calculator
Enter area and depth — get tons (or tonnes) of gravel to order.
Inputs
ft
ft
tons / cu yd
Crushed stone ≈1.4, pea gravel ≈1.3, sand ≈1.5 (tons per cubic yard)
$
%
🧱 Calculator 9 of 9
Concrete Calculator
Enter slab dimensions and thickness — get bags or ready-mix cubic yards to order.
Inputs
ft
ft
$
$
%
📐 Reference
The Complete Guide
Coverage rates, waste factors and standards used by every calculator on this site — so you can see the reasoning, or adjust for your specific product.
Waste factors, by job
Waste allowance exists because raw area or length is never what you actually buy. Cuts around fixtures, breakage in transit, pattern matching and the sizes materials are actually packaged in all eat into your material — and running short mid-job costs more than buying slightly extra up front.
Material
Typical waste
Why
Paint
0% (covered by coats)
Coverage rates already assume typical application loss
Tile — straight lay
10%
Edge cuts, breakage
Tile — diagonal / pattern
15–20%
More angled cuts, more offcuts wasted
Wallpaper
10%+
Strip trimming, pattern repeat matching
Lawn seed
5%
Uneven spread, edges
Mulch / gravel
10%
Settling, uneven ground, spillage
Fence pickets
5%
End cuts, occasional splits
Decking boards
10%
End trims, staggered seams
Concrete
10%
Uneven sub-grade, spillage, form overfill
Coverage & yield references
Material
Standard rate
Interior paint
~350 sqft / gallon / coat (~8.6 sqm / litre)
Lawn seed, new lawn
6 lb / 1,000 sqft (~2.9 kg / 100 sqm)
Lawn seed, overseed
4 lb / 1,000 sqft
Mulch depth
2–4 in (5–10 cm) typical
Gravel path depth
2–3 in; driveway base 4–6 in
Concrete slab
4 in standard, 5–6 in driveway
80 lb concrete bag yield
0.6 cu ft (≈45 bags per cu yd)
Fence post spacing
6–8 ft (1.8–2.4 m)
Deck joist spacing
16 in o.c. standard, 12 in for composite
1 cubic yard
27 cubic feet
Unit conversions used throughout
1 ft = 0.3048 m · 1 in = 2.54 cm
1 sq ft = 0.0929 sq m · 1 cu ft = 0.0283 cu m
1 lb = 0.4536 kg · 1 US gallon = 3.785 litres
A note on accuracy
These figures are industry-standard averages, not a substitute for your specific product's coverage or yield printed on the packaging. Irregular rooms, heavy texture, old porous surfaces and non-standard material sizes all shift the real number — when in doubt, round up rather than down, and keep the receipt.