Compound Interest Calculator

About Compound Interest Calculator

Use Compound Interest Calculator whenever you need reliable, immediate execution: See exactly how much your investment grows over time with any rate, tenure and compounding frequency. Using it is a three-step job: 1) Open Compound Interest Calculator and review the inputs, units, and data-handling notice shown on its page, 2) Enter the information requested by this tool and adjust only the options that apply to your task, 3) Review the result and use the available copy, download, or reset controls. Built as a focused utility in our calculators library, it is available in a modern desktop or mobile browser without requiring account registration or software installation.

Compound Interest Calculator is a free, browser-based compound interest from ProfitTool. See exactly how much your investment grows over time with any rate, tenure and compounding frequency. Review any usage notes shown on this page before relying on its availability. Review the tool's data-handling notice before entering sensitive information; some features store settings locally or contact external services.

Working alongside the Loan EMI Calculator? keep Time Cost Calculator open in a second tab.

Popular Use Cases

• Case 1
  Model a loan, mortgage or credit-card payoff before signing anything.
• Case 2
  Track fitness targets — BMI, BMR, water intake, calories and body fat.
• Case 3
  Split bills, tips and shared expenses without the drama.
• Case 4
  Convert grades, GPAs and academic scores between systems.

Technical Limitations & Boundary Conditions

• Assumes a constant fixed annual rate of return; equity and bond markets experience real annual volatility.
• Does not deduct capital gains tax or annual advisory/fund expense ratios.

Key Terms Explained

Principal

The original amount borrowed or invested, before any interest is applied.

APR

Annual Percentage Rate — the yearly cost of a loan including fees, which is what makes it comparable between lenders.

Compounding

Earning interest on previously earned interest. Frequency (monthly vs annually) meaningfully changes the total.

Amortisation

The schedule showing how each payment splits between interest and principal over the life of a loan.

Compound Interest with Recurring Monthly Contributions

Compound interest compounds earnings upon previously accumulated interest. When paired with regular monthly contributions, the power of exponential growth generates substantial geometric returns over multi-year horizons.

Future Value (FV) = [P × (1 + r/n)^(nt)] + [PMT × (((1 + r/n)^(nt) - 1) / (r/n))]
Where:
P = Initial Principal Deposit
r = Annual Interest Rate (decimal: 7% = 0.07)
n = Compounding Frequency per Year (12 = monthly)
t = Investment Period in Years
PMT = Monthly Contribution Amount

Worked Step-by-Step Example

Principal Growth = $5,000 × (1 + 0.075/12)^180 = $15,348.65
Contributions Growth = $250 × [((1 + 0.075/12)^180 - 1) / (0.075/12)] = $82,793.18
Total Portfolio Value = $15,348.65 + $82,793.18 = $98,141.83
Total Out-of-Pocket Deposits = $5,000 + ($250 × 180) = $50,000
Total Interest Earned = $98,141.83 - $50,000 = $48,141.83

Why this matters

Money and health decisions get made on rough mental maths far too often. Running the actual numbers takes thirty seconds and routinely changes the answer — whether that's a loan you shouldn't sign, a rate you should be charging, or a target you can realistically hit.

How to use Compound Interest Calculator

1. 1Open Compound Interest Calculator and review the inputs, units, and data-handling notice shown on its page.
2. 2Enter the information requested by this tool and adjust only the options that apply to your task.
3. 3Review the result and use the available copy, download, or reset controls. Processing and storage behavior vary by tool.

Already used our Daily Water Intake Calculator? try Loan EMI Calculator to finish the job.

Frequently Asked Questions

Guides that explain Compound Interest Calculator

Background reading from the ProfitTool Knowledge Hub.