About BuildCalculators
Free construction calculators that show their working — built by someone who needed them on site.
Who builds this
BuildCalculators is built and maintained by Arif Hossain. I hold a four-year diploma in civil engineering and spent a year working on site before starting this.
I want to be straightforward about what that means. I am not a licensed professional engineer, and this site does not pretend to be one. What a diploma and a year in the field gave me was a clear view of where estimating actually goes wrong — depth entered in inches against lengths in feet, material ordered to a compacted volume with no allowance for how it arrives loose, a driveway quoted without anybody working out the tonnage first. Those are not advanced problems. They are arithmetic problems that cost real money, and they happen constantly.
The calculators here are the ones I wanted while I was working. That is the whole origin.
Why the formula is always on the page
Most estimating tools hand you a number and hide how they got there. That is fine until the number looks wrong — and then you cannot tell whether you mistyped a dimension, the tool assumed a different density, or it quietly rounded in its own favour.
Every result on this site prints the expression behind it and names the constants it used. Every constant is published on the methodology page with its source, and each one is checked by an automated test that runs on every build. If a value changes, the build fails unless the change was deliberate.
That is the point of the site. Not that the numbers come from me — but that you do not have to take my word for any of them.
What this site will not do
It will not size a structural element. Footings, retaining walls, lintels and anything carrying load need a qualified engineer and a check against your local building code. A volume calculator tells you how much concrete fills a form; it cannot tell you whether the form is the right size. That distinction matters, and I am not going to blur it.
It also will not replace a site visit or a written quote. Access, drainage, existing subgrade and disposal are decided by conditions no calculator can see.
Corrections
If a number here is wrong, tell me and I will fix it. Confirmed corrections are logged publicly on the changelog with the date and what changed, so anyone who relied on the earlier figure can see that it moved.
Getting it right beats being consistent with what I have already published. Report anything via the contact page — include the calculator and the inputs you used, which makes it much faster to reproduce.
How the site is funded
Advertising. Every calculator is free, with no account, no usage limit and no paywalled results. Ad slots sit below the calculator so the tool is usable the moment the page loads.