Compound Interest & Investments

Helpful functions for working with investments & compound interest

Compound Interest

$1,000 after 3 years at 7%                    | $1,225.04

By default a yearly compounding interval is assumed, but you can also specify a monthly or quarterly compounding interval:

$1,000 for 3 years at 7% compounding monthly      | $1,232.93
$1,000 for 3 years at 7% compounding quarterly   | $1,231.44

You can also get just the interest generated over a time period:

interest on $1,000 after 3 years @ 7%                        | $225.04
interest on $1,000 for 3 years at 7% compounding monthly     | $232.93
interest on $1,000 for 3 years at 7% compounding quarterly   | $231.44

Return on Investment (ROI)

$500 invested $1,500 returned                                   | 2x
annual return on $1,000 invested $2,500 returned after 7 years  | 13.99%

Investment required for monthly/annual return

This function is useful when you have a target income you'd like to receive per month or year from a given bank deposit or investment (where you know the annual ROI).

investment required for $10k/month at 5%                        | $2.4M
deposit needed for $42k/year at 7.5%                            | $560k

Present Value of Future Money

present value of $1,000 after 20 years at 10%         | $148.64