Free tools
Small calculators for the questions that come up around jewellery and floor plans. No sign-up, they run in your browser, and each one shows the formula behind its answer.
Gold weight calculator
Work out how much a gold piece weighs from its dimensions, from its metal volume, or from its weight in another karat. Every figure is volume × the alloy's density, with the density shown.
Gold value calculator
Enter the weight and the karat to see what the gold in a piece is worth at today's spot price, how much pure gold it contains, and what a dealer typically offers for it.
Ring size converter
Convert a ring size between the US, UK, European and Swiss systems and the inner diameter and circumference in millimetres — the numbers a jeweller and a 3D model actually use.
Room area calculator
Add your rooms by length and width to get each room's floor area, the total in square metres and square feet, how much flooring to buy and how much skirting you need.
Floor plan scale calculator
Find the scale of a floor plan from one labelled dimension, then turn any length you measure on the drawing into real metres — or work out how long to draw something.