Free tool

Trade calculators in ChatGPT

You are already asking ChatGPT how much concrete a slab takes. The trouble is that it works the answer out from whatever it can remember, shows you none of the assumptions, and gets the UK bag sizes and ready-mix rounding wrong often enough to matter on site.

This app gives ChatGPT the same calculators that run on this website. Ask in your own words, get the number, the breakdown and every assumption it made, with a link to the full calculator if you want to change something.

How it works

Add the app in ChatGPT, then ask normally: *how much concrete for a 4 by 3 metre slab at 100mm?*
ChatGPT calls the calculator rather than guessing. The answer comes back with the volume, the ready-mix order, the bag count and the waste percentage it used.
Every answer links to the calculator on this site, so you can change the mix, the depth or the waste and see it update.
If you leave something out, it asks. It will not invent a width to finish a sum.

Ten calculators

The calculators

Ten of them, and every one gives the same answer as the calculator on this site, because both run the same code. A test suite checks that on every build.

Concrete
Volume, bags and a ready-mix order for a slab
The web version
Gravel
Tonnes and bulk bags of gravel for an area
The web version
MOT Type 1
Tonnes and bulk bags of Type 1 at a compacted depth
The web version
Bricks and blocks
Bricks or blocks and the mortar for a wall
The web version
Screed
Sand and cement for a screed, and how long it takes to dry
The web version
Radiator BTU
BTU and watts a room needs
The web version
Markup and margin
Sell price from a cost and a markup, with the margin
The web version
VAT
Add or take off 20% VAT
The web version
CIS deduction
What the contractor deducts, and what lands in the bank
The web version
Late payment interest
Statutory interest and compensation on an unpaid invoice
The web version

Bag sizes, densities, mix ratios, VAT and CIS rates and the statutory late payment rate are held in one place and dated. When a rate changes we change it once, and the website, this app and the figures in our guides all move together.

What it can see

The numbers you give it, for as long as it takes to work out the answer. There is no sign-in, no account and no database behind this app, so there is nothing for it to keep. It cannot see your other chats, your files or anything else in your ChatGPT account.

No sign-in and no account
Nothing stored, because there is no database behind it
No access to the rest of your ChatGPT account

The full detail is in the privacy policy, and the terms say what the figures are for. If something looks wrong, tell us.

Free

Add it in ChatGPT

It is free, there is nothing to sign up for, and you can remove it at any time.

Prefer a browser? Every one of these runs on this site as well, free and with no sign-up, on the free tools page.

Know the price before you call

Tell us your trade, the towns you cover and what you've got online now. You'll get a fixed price and a timescale in writing.

We reply within one working day.

Get my website plan Call 0161 399 4054

Prefer to talk it through first? Give us a call.