Because the UAE has no personal income tax, your quoted package is your take-home in full, there's no PAYE-equivalent deduction to model. This calculator's only real job is the currency conversion and the UK/Ireland tax calculation on the other side: it takes your monthly AED package, converts it to GBP or EUR at the exchange rate you set, and runs that converted gross figure through the exact same UK (Income Tax + National Insurance) or Ireland (Income Tax + USC + PRSI) tax engines used across the rest of this site.
The result is a genuinely apples-to-apples number: what you'd keep if that exact gross salary, expressed in pounds or euros, were taxed as a UK or Irish employee. The gap between that figure and your full tax-free UAE amount is exactly what 0% income tax is worth to you on that specific package, no more, no less.
What it deliberately does not do is answer "where does my money go further". That requires a real cost-of-living comparison: rent (which runs materially higher in London and, to a lesser extent, Dublin, than in most UAE housing markets), healthcare, schooling if you have children, and your actual spending habits. We show a single dated Numbeo cost-of-living snapshot as a directional signal, not because it's precise, but because pretending cost of living doesn't exist would be its own kind of dishonesty. Treat it as a prompt to build your own real budget, not as the final answer.