PV of Future Money
How much is a future lump sum worth in today's dollars?
PV of Periodic Payments
Present value of a stream of equal payments - ordinary annuity or annuity due.
What Is Present Value?
Present value (PV) is the current worth of a future sum of money, given a specific discount rate. It is based on the time value of money: a dollar available today is worth more than a dollar available in the future because today's dollar can be invested and earn returns.
PV answers the question: if I need $X at a future date, how much do I need today - invested at a given rate - to reach that amount? Or equivalently: given a future cash flow, what is its worth in today's dollars?
This means you would need $7,472.58 today, invested at 6% per year, to have exactly $10,000 in 5 years. The $2,527.42 difference is the interest earned between now and then - money the investment generates on your behalf.
The Discount Rate
The discount rate reflects the opportunity cost of capital: the return you give up by choosing this investment over the next best alternative at the same risk level. A higher discount rate means future cash flows are worth less today, because you assume you could earn more with the money right now. A lower rate makes future cash flows more valuable.
Present Value of an Annuity
When a series of equal payments (PMT) is made over multiple periods at a fixed interest rate, the combined present value is the sum of the PV of each individual payment.
For 10 annual payments of $100 at 6%:
- Ordinary annuity PV = 100 x [1 - (1.06)^(-10)] / 0.06 = $736.01
- Annuity due PV = $736.01 x 1.06 = $780.17
The annuity due is $44.16 higher because each payment arrives one period earlier and therefore discounts for one fewer period.
Ordinary Annuity vs Annuity Due
| Type | When Paid | Common Use | PV vs Ordinary |
|---|---|---|---|
| Ordinary Annuity | End of period | Mortgages, car loans, bond coupons | Baseline |
| Annuity Due | Beginning of period | Rent, insurance premiums, leases | Higher by (1+r) |
PV vs NPV: The Key Distinction
Present value and net present value are closely related but answer different questions.
Present value (PV) is the current worth of one future cash flow or a stream of identical payments. It asks: what is this future amount worth today? There is no comparison to a cost - it is a pure discounting exercise.
Net present value (NPV) subtracts the initial cost from the present value of all expected future cash flows. It asks: after paying for this investment, how much value does it create (or destroy) in today's dollars?
Example: you invest $5,000 today to receive $1,200 per year for 6 years at a 10% discount rate.
- PV of annuity = 1,200 x [1 - (1.10)^(-6)] / 0.10 = $5,226.70
- NPV = $5,226.70 minus $5,000 = +$226.70
The positive NPV means the investment earns slightly above the 10% required return. Had the discount rate been 11%, the NPV would turn negative and the investment would fail to meet the required return.
How the Discount Rate Affects PV
Small changes in the discount rate produce large changes in present value, especially for cash flows far in the future. This is one of the most important and often underestimated aspects of discounted cash flow analysis.
PV of $10,000 Received in the Future at Different Rates
| Years Away | At 3% | At 6% | At 10% | At 15% |
|---|---|---|---|---|
| 1 year | $9,709 | $9,434 | $9,091 | $8,696 |
| 5 years | $8,626 | $7,473 | $6,209 | $4,972 |
| 10 years | $7,441 | $5,584 | $3,855 | $2,472 |
| 20 years | $5,537 | $3,118 | $1,486 | $611 |
| 30 years | $4,120 | $1,741 | $573 | $151 |
At a 3% rate, $10,000 in 30 years is worth $4,120 today. At 15%, it is worth only $151. The same cash flow is 27 times more valuable under one assumption than the other. This sensitivity is why discount rate selection is the most consequential judgment in any DCF analysis.
Real-World Uses of Present Value
Mortgage and Loan Pricing
A mortgage is the lender's present value calculation in reverse. The lender gives you a lump sum today (the loan amount) and receives a stream of monthly payments over 15 or 30 years. The present value of those payments at the agreed interest rate exactly equals the loan amount on day one.
Bond Valuation
A bond's fair market price is the present value of all its future cash flows: each coupon payment and the face value at maturity, all discounted at the current market yield. When interest rates rise, the discount rate rises, the PV of future coupons falls, and bond prices fall. This is the direct mathematical reason for the inverse relationship between bond prices and interest rates.
Retirement Planning
The "lump sum needed at retirement" is a present value question. If you need $60,000 per year in retirement for 25 years and your portfolio earns 5%, the PV of that annuity is the amount you must accumulate by retirement day. PV = 60,000 x [1 - (1.05)^(-25)] / 0.05 = $845,566.
Business Valuation
The intrinsic value of a business in a discounted cash flow model is the present value of all projected free cash flows, discounted at the company's WACC. This includes a terminal value: the present value of all cash flows beyond the explicit forecast period, typically modeled as a growing perpetuity.
Court Settlements and Structured Payments
Lump-sum settlements are compared to structured payment streams using present value. A plaintiff choosing between $500,000 today or $60,000 per year for 10 years should use PV at their personal discount rate to determine which is worth more. At 5%: PV of annuity = $463,130 - so $500,000 today is better. At 2%: PV = $538,259 - so the annuity is better.
Perpetuities: PV of an Infinite Stream
A perpetuity is an annuity that pays forever. The present value formula simplifies dramatically because the sum of an infinite geometric series converges to a finite number when the discount rate exceeds zero.
This is not just theoretical. UK government bonds called "consols" historically had no maturity date. More practically, the Gordon Growth Model uses the perpetuity formula to value stocks that pay dividends expected to grow at a constant rate:
The growing perpetuity formula also forms the basis of the terminal value in DCF models. After the explicit forecast period (typically 5 to 10 years), the analyst assumes cash flows grow at a constant long-run rate forever. The terminal value captures the present value of those perpetual cash flows and is often the largest single component of a DCF valuation.