Interest Calculator

Estimate simple and compound interest growth in one calculator.

This Interest Calculator helps users project future balance using principal, annual interest rate, time period, and optional monthly contributions. In simple interest mode, earnings are calculated only on the original principal. In compound interest mode, earnings are added back into the balance so future gains can build on earlier growth.

The tool is useful for savings plans, investment comparisons, contribution planning, and understanding how time and rate affect growth. It shows final balance, total interest, total contributions, principal growth, and a yearly growth snapshot to make the projection easier to review.

What can this interest calculator help with?

• Compare simple and compound interest outcomes
• Measure the effect of monthly contributions over time
• Test different rates and time periods
• Plan savings or investment targets
• Review yearly growth with a quick table

How to use it

1. Select simple or compound interest mode.
2. Enter principal, annual rate, and time period.
3. Add monthly contributions and compound settings if needed.
4. Review the result cards and yearly growth table.

FAQ

What is the difference between simple and compound interest?

Simple interest is earned only on the original principal. Compound interest adds earnings back into the balance so later periods can earn on previous gains.

Are monthly contributions included?

Yes. The calculator tracks monthly additions separately and includes them in the projected balance.

Is this a guaranteed financial forecast?

No. The output is an estimate for planning and comparison, not a guaranteed return.