Litres of paint for a wall or a roof from the area, the number of coats and the spread rate, with the tin sizes to buy.
This is the job the page opens with, already worked out. Change any figure above and the answer changes with it.
8.25litres · 2 coats on 30 m²
30 m² ÷ 8 m²/litre = 3.75 litres a coat, × 2 coats, plus 10%.
Every one has its own page, so you can bookmark the one you use most.
New tools get built when the admin gets annoying enough. Leave your email and you will hear when the next one lands. What you do on site is what decides what gets built, so it is worth saying.
These come from ten years on site: first in contracting on production and civil works, then in consulting doing construction monitoring for consultants appointed by the City of Cape Town. Working a quantity out twice, because the first answer was on a piece of board that blew away, is a thing that happens to everybody.
Every calculator shows the formula it used and the assumptions it made, because a number with no working behind it is worth nothing on site. Where a figure varies by material or supplier, it is an input you can change rather than something hidden. Check the answers against your own specification and your supplier's own figures before you order. These help you work faster, they do not replace your own judgement.
If they save you time, the paid IT Admin Buster packs cover the admin side: progress report templates, daily diaries, inspection checklists and the wording banks that go with them.