Investing tools

Turn a start value, an end value and a period into one annual growth rate — with your own deposits taken back out of it.

What a percentage point of fees actually costs over a working life, against a low-cost alternative.

What a return is worth after inflation and tax — the growth in what the money can actually buy.

How long money takes to double at a given return — the mental shortcut, and the exact answer beside it.

A starting split between growth and defensive assets based on your age, your horizon and how you actually behave in a fall.

The buy and sell amounts that bring each holding back to its target weight, using new money first where possible.

Investing a windfall all at once against drip-feeding it in — the cost of waiting when markets rise, and why people still wait.

The true cost of a conversion: the stated fee plus the margin hidden in the exchange rate you were given.

Gross up an imputed dividend, work out the tax on it, and see whether the credits leave a refund.

Tax on dividend income, with any tax-free allowance and the rate for your band.

Capital gains tax with the annual exempt amount and the gain stacked on income to decide the rate.