Interactive Budget Planner

The rule allocates half of take-home pay to needs, thirty percent to wants, and twenty percent to savings and debt repayment. Its usefulness is not precision, it is that it gives you a reference point in about a minute.

It assumes housing costs are reasonable relative to income, which is exactly the assumption that fails in expensive cities. If rent alone is half your income, the split is not a target you have failed to hit, it is a diagnosis: the fixed costs are the problem, and no amount of discipline on the discretionary side will fix it.

The line between a need and a want is less obvious than it looks. Groceries are a need, the delivery fee is not. Treat the categorisation as a decision you are making rather than a fact you are recording.

Budget from take-home pay, not gross. The tax and deduction gap is large enough that planning against gross produces a shortfall every month with no obvious cause.

Annual and irregular costs are what break otherwise sound budgets: insurance, road tax, subscriptions billed yearly, gifts, the dentist. Divide each by twelve and carry it as a monthly line, otherwise those months look like personal failures rather than arithmetic you skipped.

Everything you enter stays in your browser. Nothing about your income or spending is uploaded, which is the property you actually want from a page you type your salary into.