Percentage Calculator

Percentages are one of the most used and most misused numbers in everyday money. They appear on everything from discounts and interest rates to pay rises and tax, and because they are quoted in different ways, the same underlying change can sound large or small depending on the frame. A few habits make them reliable. The basic operation is a proportion of a hundred. A percentage of a number is that number multiplied by the rate over a hundred, so fifteen per cent of two hundred is thirty. Finding what percentage one number is of another reverses the operation: divide the part by the whole and multiply by a hundred. Those two directions cover most of what people need, including tips, discounts, tax and margins. Percentage change is the third common case and the one that trips people up. It is the difference divided by the starting value, so a rise from fifty to seventy-five is fifty per cent, while a fall from seventy-five back to fifty is a third. The asymmetry is real: gains and losses of the same percentage do not cancel, because each is measured against a different base. A stock that falls fifty per cent then rises fifty per cent has not recovered — it is down twenty-five per cent. The same trap appears in sequence. Applying two reductions of twenty per cent each is not a forty per cent reduction; it is a thirty-six per cent reduction, because the second applies to the already-reduced amount. Percentages multiply rather than add, which is why stacked discounts and compounded interest behave differently from what intuition expects. Reading whether a figure is a percentage of the original or of the current value tells you which calculation applies. This calculator handles the four most common percentage questions in one place: a percent of a number, one number as a percent of another, the percent change between two numbers, and adding or subtracting a percent. Enter your values, choose the question you are asking, and check the labels carefully, since the same two numbers produce very different answers depending on which relationship you mean.

This calculator returns estimates for general information only. It is not financial, investment, tax or legal advice, and it cannot replace guidance from a qualified professional who knows your circumstances. Figures such as loan payments, investment growth and retirement projections are simplified models based on the inputs and assumptions you provide, not guarantees of future results.