When you have a single payment that will be made to you, in this case $4, and you know that it will be paid in a certain number of years, in this case 21 years, you can use the present value formula to calculate what that $4 is worth today.

Below is the present value formula we'll use to calculate the present value of $4 in 21 years.

$$Present\: Value = \dfrac{FV}{(1 + r)^{n}}$$

We already have two of the three required variables to calculate this:

- Future Value (FV): This is the $4
- n: This is the number of periods, which is 21 years

So what we need to know now is r, which is the discount rate (or rate of return) to apply. It's worth noting that there is no correct discount rate to use here. It's a very personal number than can vary depending on the risk of your investments.

For example, if you invest in the market and you earn on average 8% per year, you can use that number for the discount rate. You can also use a lower discount rate, based on the US Treasury ten year rate, or some average of the two.

The table below shows the present value (PV) of $4 paid in 21 years for interest rates from 2% to 30%.

**As you will see, the present value of $4 paid in 21 years can range from $0.02 to $2.64.**

Discount Rate | Future Value | Present Value |
---|---|---|

2% | $4 | $2.64 |

3% | $4 | $2.15 |

4% | $4 | $1.76 |

5% | $4 | $1.44 |

6% | $4 | $1.18 |

7% | $4 | $0.97 |

8% | $4 | $0.79 |

9% | $4 | $0.65 |

10% | $4 | $0.54 |

11% | $4 | $0.45 |

12% | $4 | $0.37 |

13% | $4 | $0.31 |

14% | $4 | $0.26 |

15% | $4 | $0.21 |

16% | $4 | $0.18 |

17% | $4 | $0.15 |

18% | $4 | $0.12 |

19% | $4 | $0.10 |

20% | $4 | $0.09 |

21% | $4 | $0.07 |

22% | $4 | $0.06 |

23% | $4 | $0.05 |

24% | $4 | $0.04 |

25% | $4 | $0.04 |

26% | $4 | $0.03 |

27% | $4 | $0.03 |

28% | $4 | $0.02 |

29% | $4 | $0.02 |

30% | $4 | $0.02 |

As mentioned above, the discount rate is highly subjective and will have a big impact on the actual present value of $4. A 2% discount rate gives a present value of $2.64 while a 30% discount rate would mean a $0.02 present value.

The rate you choose should be somewhat equivalent to the expected rate of return you'd get if you invested $4 over the next 21 years. Since this is hard to calculate, especially over longer periods of time, it is often useful to look at a range of present values (from 5% discount rate to 10% discount rate, for example) when making decisions.

Hopefully this article has helped you to understand how to make present value calculations yourself. You can also use our quick present value calculator for specific numbers.