Investment Yield (Growth Rate) Calculator - how well have your savings or investments performed?

Click here to launch the calculator

This calculator works out the annualised growth rate of an investment over a number of years based upon the original investment.

It can calculate the growth rate of single-premium investment (such as an investment bond) or a regular premium investment (such as a personal pension).

Please note that the calculator assumes that no withdrawals have been taken from the investment during the period in question.

While calculating a yield or growth rate for a single-premium investment is relatively straightforward, calculating an average growth rate based on a regular monthly contribution is more difficult. In effect it is more of a very close approximation.

For instance, if you were to pay £50 per month into a savings plan for ten years and at year ten it was worth £10,000, in order to calculate the true growth rate exactly, you would need to calculate the number of units purchased each month, then track the growth of those specific units for the remainder of the term. This would effectively entail a polynomial order of 120 separate calculations to solve.

Also you would need accurate details of each payment, and assuming you actually had all the information, it would still be a time-consuming task. Therefore, if this is not possible, the alternative method is to use an iterative approach, incorporating the Newton-Raphson root-finding method (similar to methods used in Excel functions such as RATE). This is the method used by this calculator.

The figures projected by the calculator are only for guidance purposes, and are by no means guaranteed.

Recent Financial Topics

I am a psychologist working for the NHS and privately. I am not contributing into a pension as I am investing my earnings into furthering my career - but I am getting worried about the future.

I'm a 45-year-old professional who rents and has no pension - should I worry? Steve Webb replies
04/12/2023 01:00 AM

The uPVC windows are less than half the price - but many of our neighbours have wooden ones and we're worried not doing so could make our house worth less.

Should we get uPVC double glazing or will expensive wooden frames boost our home's value?
04/12/2023 01:00 AM

A new report by Policy Exchange said more aspiring homeowners should be able to commission and build their own houses amid the cost-of-living crisis.

Reforms are needed to make it easier for young people to buy a home to restore faith in capitalism, ministers are warned
03/12/2023 08:57 PM