Quick Answer
A $10,000 lump sum invested at 7% annually for 20 years has an estimated future value of approximately $38,697, with approximately $28,697 in estimated interest earned.
Common Examples
| Input | Result |
|---|---|
| $10,000 lump sum at 7% for 20 years | Estimated future value: approximately $38,697 |
| $5,000 lump sum at 5% for 10 years | Estimated future value: approximately $8,144 |
| $50,000 lump sum at 8% for 30 years | Estimated future value: approximately $503,133 |
| $5,000/year annuity at 7% for 20 years | Estimated future value: approximately $204,977 |
| $10,000/year annuity at 6% for 30 years | Estimated future value: approximately $790,582 |
How It Works
This calculator uses the time value of money principle: money today is worth more than the same amount in the future because it can earn a return over time.
Lump Sum Future Value:
FV = PV x (1 + r)^n
Where:
- FV = estimated future value
- PV = present value (initial investment)
- r = annual interest rate (as a decimal)
- n = number of years
This answers the question: “If I invest PV today at rate r, how much will it be worth in n years?”
Annuity Future Value (Ordinary Annuity):
FV = PMT x [((1 + r)^n - 1) / r]
Where:
- PMT = annual payment amount
- r = annual interest rate (as a decimal)
- n = number of years
This calculates the total accumulated value of making equal annual payments, with each payment earning compound interest for the remaining years. Earlier payments earn more interest because they are invested for a longer period.
The Power of Compound Interest
The key factor in future value is the compounding effect. Interest earns interest over time, creating exponential growth. At 7% annually, money approximately doubles every 10.3 years (using the Rule of 72: 72 / 7 = 10.3). This means $10,000 becomes approximately $20,000 in 10 years, $40,000 in 20 years, and $80,000 in 30 years.
Zero Percent Rate Edge Case
When the interest rate is 0%, the future value simply equals the total contributions. For a lump sum, FV = PV. For an annuity, FV = PMT x n. No interest is earned, so the total is just the sum of all deposits.
Worked Example
For a $10,000 lump sum at 7% for 20 years: FV = $10,000 x (1 + 0.07)^20 = $10,000 x (1.07)^20 = $10,000 x 3.8697 = approximately $38,697. Total contributions = $10,000. Estimated interest earned = $38,697 - $10,000 = approximately $28,697.
For a $5,000/year annuity at 7% for 20 years: FV = $5,000 x [((1.07)^20 - 1) / 0.07] = $5,000 x [(3.8697 - 1) / 0.07] = $5,000 x [2.8697 / 0.07] = $5,000 x 40.9955 = approximately $204,977. Total contributions = $5,000 x 20 = $100,000. Estimated interest earned = $204,977 - $100,000 = approximately $104,977.
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