Investment Growth Calculator UK: Project Your ISA or SIPP Pot

See what a starting pot plus regular monthly contributions could grow to over time. The key honesty most calculators skip: fees and inflation both eat into your real return, so we deduct your annual charges and, if you ask, show the figure in today's spending power rather than a flattering future-pounds headline.

The maths compounds monthly. We subtract your annual fee from the growth rate, then, if the box is ticked, discount the final figure back to today's spending power using your inflation assumption. A common sensible set of inputs for a global index fund is a 7% return, around 0.4% all-in fees and 2.5% inflation, but these are assumptions, not promises. Markets do not return a smooth number each year, and past performance does not predict the future.