Lump Sum Calculator for Compound Investment Growth
Project the future value and interest earned on a one-time investment using an annual return, time period, and selected compounding frequency.
Enter a one-time investment, annual return, years, and compounding frequency to project future value and interest earned.
About lump-sum compound growth
A lump sum calculator answers a simple planning question: if you invest a single amount today and leave it alone, what might it be worth later? Retirement rollovers, inheritance deposits, bonus savings, and one-time brokerage transfers all follow this pattern. Unlike a monthly contribution plan, there is no additional cash added each period—only the original principal and the return you assume. The lump sum calculator uses compound interest. Future value equals principal times (1 + annual rate ÷ 100 ÷ compounding periods) raised to compounding periods times years. Interest earned is future value minus principal. Monthly compounding uses 12 periods per year, quarterly uses 4, and annual uses 1. More frequent compounding produces a slightly higher future value at the same nominal annual rate because interest is added to the base more often. A 7% annual return is a common long-run equity illustration, not a forecast. Actual market returns vary by year, and a constant rate assumption smooths that path into a single curve. Inflation, taxes on dividends or realized gains, and account fees all reduce purchasing power relative to the pre-tax future value shown. A 0% rate case is useful as a control: the future value equals the principal and interest earned is zero. Compounding frequency should match how the product credits interest. A savings account may compound daily or monthly; a bond yield illustration may use annual or semi-annual periods. Enter the annual return as a percent (7 for 7%), not 0.07. Years may be fractional in the math if you type a decimal, but the examples use whole years for clarity. Use the lump sum calculator to compare monthly versus annual compounding, to see how a decade of 7% growth roughly doubles a $10,000 deposit in the worked example, or to test a conservative 5% case. Treat the projection as a what-if, not a guaranteed balance, and revisit the rate if you are modeling cash, bonds, or a diversified portfolio with a different expected return.
Future value = principal × (1 + annual rate ÷ 100 ÷ compounding periods)^(compounding periods × years); interest earned = future value − principal.
Lump-sum investment examples
These worked examples use the same compound-interest formula as the lump sum calculator.
| Input | Output | Note |
|---|---|---|
| $10,000 at 7% for 10 years, monthly | $20,096.61 | Monthly compounding grows $10,000 to $20,096.61, so interest earned is $10,096.61 over the decade. |
| $5,000 at 5% for 5 years, annual | $6,381.41 | Annual compounding at 5% turns $5,000 into $6,381.41, with $1,381.41 of interest earned. |
| $20,000 at 0% for 3 years | $20,000.00 | A 0% return leaves future value equal to principal and shows $0.00 of interest, a useful no-growth check. |
How to project lump-sum growth
- Enter the Initial Investment, the one-time amount you deposit today.
- Enter Annual Return (%) as a percent, such as 7 for a 7% assumed yearly rate.
- Enter Investment Period (Years) and Compounding Periods per Year (12 for monthly, 1 for annual).
- Select Calculate to see future value and interest earned, then change the rate or frequency to compare scenarios.
Lump sum calculator FAQ
What compounding frequency should I enter?
Match the product: 12 for monthly, 4 for quarterly, 2 for semi-annual, and 1 for annual. Daily compounding can be modeled with 365 if you want that convention; more periods raise future value slightly at the same nominal rate.
Does the lump sum calculator add monthly contributions?
No. It models a single deposit that compounds over time. If you plan to add money each month, a regular-contribution or annuity-style calculator is the better fit because those formulas include a payment stream.
Is a 7% annual return a guarantee?
No. Seven percent is only an illustration often used for long-run diversified equity returns. Markets, fees, and taxes can produce a higher or lower realized rate, so run a conservative case as well as a base case.
How should I enter the annual return?
Type a percent, not a decimal. Enter 7 for 7%, or 5.5 for five and one-half percent. The formula divides that figure by 100 and then by the compounding periods per year.
Are taxes and inflation included?
The future value is a pre-tax, nominal amount in the same units as the principal. Inflation and taxes on interest, dividends, or capital gains are not deducted, so purchasing power and after-tax cash can be lower than the displayed balance.