Compound Interest Calculator — Growth & Future Value Guide

Calculators · Free guide
Investment growth compound interest chart — 3D illustration

Project how savings grow with compound interest. Enter principal, annual rate, years, and compounding frequency — see future value, total interest earned, and a year-by-year growth breakdown. The TetraKits Compound Interest Calculator runs entirely in your browser — free, private, and ready on mobile or desktop.

Overview

Retirement planning, CD comparisons, and teaching financial literacy all hinge on compound growth — not linear simple interest. Enter principal, rate, and compounding frequency to see future value and total interest earned.

How to use the compound interest calculator

  1. Enter principal and rate — Type the starting amount and annual interest rate as a percentage. Example: $10,000 at 5% per year.
  2. Set time and frequency — Enter years and choose compounding: annually, quarterly, monthly, or daily. More frequent compounding yields slightly higher returns.
  3. Read future value — See ending balance and total interest. Compare with simple interest or plan loans with the loan calculator.

Common use cases

  • Enter principal and rate: Type the starting amount and annual interest rate as a percentage.
  • Set time and frequency: Enter years and choose compounding: annually, quarterly, monthly, or daily.
  • Read future value: See ending balance and total interest.
  • Bookmark for quick access: Save the tool for repeat tasks without installing an app.

Frequently asked questions

What is compound interest?

Compound interest earns interest on both principal and previously earned interest. Formula: A = P(1 + r/n)^(nt), where n is compounding periods per year.

How does compounding frequency affect returns?

More frequent compounding (daily vs annually) produces a higher effective yield on the same nominal rate, though the difference is modest at typical savings rates.

What is the difference between simple and compound interest?

Simple interest applies only to the original principal. Compound interest reinvests earned interest — growth accelerates over time.

Can I model regular contributions?

This calculator compounds a single principal. For monthly deposits, run separate scenarios or use a dedicated savings planner.

Is this compound interest calculator free?

Yes. Unlimited projections with no signup; all math runs in your browser.