Compound Interest & Goal Calculator
Model principal, recurring contributions and compound growth over time.
Compound Interest & Goal Calculator calculation coverage
- 01
Flexible compounding
- 02
Recurring contributions
- 03
Growth versus capital
Hypothetical projection. Real returns vary and may be negative.
About this tool
A compound interest calculator projects how principal and recurring contributions may grow when returns are reinvested. Compounding earns a return on both contributed capital and previously accumulated growth.
How it works
The nominal annual rate is divided by compounding periods per year. Principal grows over the full duration; contributions arrive at completed period-ends and grow for the remaining time. Total growth is ending value minus all contributed capital.
| Parameter | How it is used |
|---|---|
| Starting principal | Capital invested at the beginning. |
| Recurring contribution | Additional amount invested each period. |
| Annual return | Hypothetical growth assumption. |
| Time and frequency | Controls the number of compounding periods. |
Two years with annual contributions
$1,000 principal, $100 contributed at each year-end, 5% nominal annual growth and annual compounding for two years.
Year 1: $1,000 × 1.05 + $100 = $1,150. Year 2: $1,150 × 1.05 + $100 = $1,307.50.
$1,307.50 ending value, including $1,200 contributed and $107.50 modeled growth.
The return is an assumption. Taxes and inflation can reduce the purchasing power of the result.
How to use this tool
- Enter starting capital and a realistic recurring contribution.
- Choose a conservative annual return, compounding frequency and time horizon.
- Compare ending value with total contributions and test lower-return scenarios.
Frequently asked questions
What does compounding frequency mean?
It is how often accumulated returns are added to the balance. More frequent compounding has a small positive effect when the nominal rate is unchanged.
Are recurring contributions compounded immediately?
The model applies contributions at the selected interval, so earlier deposits have more time to compound than later ones.
Should I use an expected or guaranteed return?
Use a cautious scenario range. Most market returns are not guaranteed, and a single assumed percentage can hide substantial uncertainty.