THE ZENUTILITY TOOLBOX

Everyday calculators Tools

Browse calculators, calendars, timers and reference tools. The complete collection is below.

Everyday calculators

Work out a sale price, savings and the combined effect of two successive discounts.

Calculate a percentage tip and split a bill between people, with a clear total and rounded shares.

Add an entered tax rate to a price or extract the tax already included in a total.

Compare gross margin and markup from a cost and selling price without mixing their denominators.

Calculate a rectangle’s area in square feet and square metres from matching length measurements.

Calculate average speed from kilometres travelled and elapsed minutes, with km/h, mph and m/s results.

Convert litres per 100 kilometres, US miles per gallon and imperial miles per gallon.

Reduce image dimensions to an aspect ratio and find a proportional height for a new width.

Estimate a display’s pixels per inch from its resolution and active-screen diagonal.