Investment Calculator

See what your investments could grow to after fund fees and inflation, or work out how much to invest each month to reach a target. Works in £, $ or C$.

Reviewed by Dany, RightSums team · Updated

Runs in your browser. Free, no sign-up.

personal-finance · Daily life · UK & US

Enter a starting amount, a monthly or yearly contribution, an expected return and the number of years. Unlike a savings calculator, this one takes off your fund and platform fees every month, lets you raise your contributions each year, and shows the result at today's prices after inflation. You can pay in at the start or end of each period. Switch to target mode to find the monthly amount needed to reach a figure such as £100,000 or $250,000. You get the final balance, what you paid in, the growth, the fees you paid and what they cost you in lost growth, plus a year-by-year table and chart. It works for the UK, the US and Canada. It is an estimate: real returns vary from year to year.

Accepted inputs

  • Country and currency (UK, US or Canada)
  • Starting amount
  • Regular contribution, monthly or yearly, at the start or end of each period
  • Expected yearly return
  • Number of years
  • Yearly fees as a % of your balance
  • Yearly increase in contributions
  • Inflation rate
  • Target amount, in future or today's money (target mode)

Outputs

  • Final balance
  • Total paid in and total growth
  • Fees paid and their cost to your final balance
  • Final balance at today's prices
  • Monthly or yearly amount needed to reach a target
  • Year-by-year table and chart
  • What more saving, more time, lower fees or lower returns would change

How to use the Investment Calculator

  1. Enter your starting amount, how much you will pay in each month or year, and if you pay at the start or end of each period.
  2. Add an expected yearly return, the number of years, your yearly fund and platform fees, any yearly increase in contributions and an inflation rate.
  3. The calculator grows your balance month by month, takes off the fee each month, adds your contributions and converts the result into today's money.
  4. Read your final balance, fees and real value, check the year-by-year table, or switch to target mode to see the monthly amount needed to reach your goal.

Frequently asked questions

How do you calculate investment growth?

Multiply your money by one plus the yearly return for each year it is invested. £10,000 at 5% a year for 10 years is £10,000 × 1.05 to the power of 10, which is £16,288.95. Regular contributions each grow for the time they are invested, and fees reduce the return you actually get.

How much will £200 a month be worth in 20 years?

About £131,053 with £10,000 to start, £200 paid at the start of each month and a 7% yearly return with 0.5% fees. You pay in £58,000. Fees take £5,862, but cost £9,725 of the final balance because that money also stops growing. At 2.5% inflation the total is worth about £79,978 at today's prices.

How much do I need to invest each month to reach $100,000?

About $362 a month over 15 years, starting from zero, if you earn 6% a year before fees of 0.5% and pay in at the start of each month. Over a shorter time or at a lower return you need more. Switch the calculator to target mode and it works this out for any amount, period and return you enter.

What return should I use in an investment calculator?

Use a rate you are comfortable planning on, not the best year you remember. Many people test a cautious rate, a middle rate and a higher one, such as 4%, 6% and 8%, to see the range. Returns are not guaranteed and shares can fall, so treat any single figure as one possible outcome.

Is this different from a compound interest calculator?

Yes. A compound interest calculator assumes a fixed savings rate. This one is built for investing: it takes off fund and platform fees, lets contributions rise each year, shows the result at today's prices after inflation and can work backwards from a target. Use the compound interest calculator for savings accounts and this one for funds or shares.

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