Home & Garden Calculators

What the Home & Garden shelf answers

Most home and garden jobs come down to the same question before they come down to money: how much do I actually need to buy? A patio needs a certain depth of hardcore, then a certain depth of concrete or slabs on top of that. A bedroom needs enough paint for two coats and enough underlay before the carpet goes down. A lawn needs turf measured to the square metre with a margin for the pieces that get cut to fit the edges. This category turns those measurements into shopping lists, tonnes, bags, boxes, bundles and litres, and rough costs, rather than leaving you to guess on the back of an envelope or take a merchant's till figure on trust. Eight calculators are live so far, covering concrete, aggregates, mulch, tiling, roofing, staircases, room area and heating or cooling sizing, and the shelf is growing: fencing, paint, wallpaper, turf and skip sizing are being built next, followed by topsoil, decking, brickwork, plasterboard and insulation.

How the four shelves divide the work

The category splits along the lines a real project actually follows, outside first, then structure, then finish, then the logistics that wrap around all three.

Garden & Landscaping

The Garden & Landscaping shelf covers what happens outside the back door: turf, fencing, decking, and the beds and borders in between. The Gravel Calculator converts an area and a depth into tonnes, US tons, bulk bags or 25kg bags for gravel, sand, ballast, topsoil or bark, and the Mulch Calculator does the same job for beds and borders, rounding the answer up to the bag sizes a garden centre actually stocks. Turf, fencing and decking calculators are next in the queue.

Building Materials

The Building Materials shelf covers the structural side: bricks, concrete, plaster and aggregates measured in bags and tonnes rather than guesses. The Concrete Calculator works out the volume for a slab, a footing, a post hole or a set of steps and converts it straight into a bag count, and the Roofing Calculator turns a house footprint and a roof pitch into roofing squares and shingle bundles. Brickwork, plasterboard and insulation calculators are coming.

Inside the Home

The Inside the Home shelf is decorating and finishing: paint, wallpaper, flooring and heating, with wastage counted honestly rather than left for you to guess. The Square Footage Calculator adds any number of rooms into one project total, the Tile Calculator works out tiles and boxes with a waste allowance that depends on the lay pattern, the Stair Calculator checks a staircase against a comfort rule and published building limits, and the BTU Calculator sizes a heater or air conditioner as an honest range rather than one falsely precise number. Paint and wallpaper calculators are next.

Big Jobs & Projects

The Big Jobs & Projects shelf is for the work that needs sizing before it needs pricing: skip hire, house clearances, house moves, and the bigger projects that draw on more than one shelf at once, a loft conversion pulling in insulation, plasterboard and roofing all in the same job. A skip size calculator is first up here.

Getting the quantities right

Measure twice and write the numbers down before you open any calculator. A room that looks rectangular from the doorway is rarely exact once you get a tape into the corners, especially in older houses, and a bed that curves round a tree is not a rectangle at all; break it into two or three shapes you can measure honestly rather than eyeballing one figure. Depth catches people out more than length or width, because it is invisible once the job is finished and easy to skimp on when you're totting up a price. Doubling a layer of gravel from 50mm to 100mm doubles the tonnage, and the difference between a 75mm and a 100mm concrete slab is a quarter more material for a small change on paper.

Wastage is not padding, it is the honest cost of cutting things to fit. A straight tile lay typically needs about 10% extra and a diagonal or herringbone lay needs 15% or more; turf needs roughly 5 to 10% for trimming round curves and obstacles; roofing waste depends on whether the roof is a simple gable or a more complex hip. Every calculator on this shelf builds a sensible default allowance in and lets you change it, but the principle carries over to materials that don't have a calculator yet: buy the extra up front, because a second delivery costs more in time and delivery charges than the leftover material would have cost the first time round.

Bags versus bulk is a straightforward sum once you have a volume. Small bags are convenient for a wheelbarrow job and for storage on a driveway with no room to tip a load, but past roughly ten bags of anything, gravel, sand, ballast, ten 25kg bags is a quarter of a tonne, a bulk bag usually works out cheaper per tonne and saves the repeated trips to the merchant. The trade-off is access: a bulk bag needs somewhere flat to sit and, more often than not, a crane offload or a forklift-equipped lorry that a narrow driveway or a shared access road can rule out. Check delivery access before you commit to the cheaper option on paper.

UK and US terms for the same job

The materials are the same either side of the Atlantic; the names, the spelling and the units often are not, and it's worth knowing both when you're reading a product label or a supplier's price list. What the UK calls a skip, the US calls a dumpster, and both come in a similar spread of sizes measured in cubic yards. Plasterboard in the UK is drywall in the US, sold in the same broad sheet sizes but priced and stocked slightly differently. Turf is sod once you're buying it by the pallet rather than the roll. Aggregates are usually priced by the tonne in the UK and by the US ton or the cubic yard in the US, which is one reason the calculators on this shelf show more than one unit at once rather than forcing a single system on every visitor. Even the spelling shifts, kerbstone against curbstone, aluminium against aluminum, so a search for a material by its US name will usually still find the right UK product once you know what to look for.

Frequently asked questions

Which calculator should I start with?

Start with the Square Footage Calculator if the job is about floor or wall area, and the Gravel Calculator or Concrete Calculator if it is about a volume of material going into the ground. Almost every other quantity on this shelf builds on one of those two starting figures.

Are these tools accurate enough to order from?

They are built for sizing a job and sanity-checking a quote, with the same waste allowances a tradesperson would use. The person doing the work should still measure on site before the order goes in, particularly for anything structural like concrete footings or a staircase.

Why does the shelf split materials from finishing?

Because that is the order a real project runs in. You settle the structure, concrete, brick, roof, before you settle the finish, paint, tile, floor, and the outdoor work usually happens on its own timeline alongside or after both. Splitting the calculators the same way keeps the shopping list for each stage separate.