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Compound Interest Calculator
Project a balance with compound growth, contributions, and flexible compounding periods.
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Model growth, regular investing, retirement income, rates, loans, and debt with transparent formulas. Your financial inputs stay in your browser.
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Start with compound growth
Enter a starting balance, rate, timeline, and optional contributions. The calculator separates money added from interest earned and shows the assumptions behind the result.
Calculate compound interestContributions
Add regular deposits
Frequency
Compare compounding periods
Inflation
View purchasing power
Results
Inspect the growth breakdown
Choose a path
Compare the scenario that matches your decision
Start from the cash flow you have now, then use the calculator built for that question.
Compound a lump sum
See how one starting balance changes with time, rate, and compounding frequency.
Compare lump sum growth
Invest on a schedule
Compare recurring contributions with a lump sum so the timing of each deposit is clear.
Compare recurring investment
Plan retirement income
Connect a retirement balance to scheduled withdrawals and test how long it may last.
Compare retirement and withdrawal
Understand borrowing cost
Compare a loan payment and total interest before choosing a repayment path.
Compare borrowing options
Calculator library
Explore all 18 financial calculators
Browse by purpose to find the right model for growth, planning, rates, or borrowing.
Growth
Model how deposits and returns build a balance over time.
6 calculators
Daily Compound Interest Calculator
See how a stated annual rate changes when interest is applied each day.
Open Daily Compound Interest Calculator
SIP Calculator
Estimate the future value of regular monthly contributions and the returns they may earn.
Open SIP Calculator
Forex Compound Calculator
Model trading account growth from a repeating return assumption and starting balance.
Open Forex Compound Calculator
Investment Calculator
Explore how an initial investment, regular additions, and a return assumption interact.
Open Investment Calculator
Future Value Calculator
Estimate the future value of money invested today or added over time.
Open Future Value Calculator
Planning
Turn savings, retirement, and withdrawal goals into scenarios.
4 calculators
SWP Calculator
Test scheduled withdrawals and see how long an investment balance may last.
Open SWP Calculator
Savings Goal Calculator
Work out a contribution plan for reaching a savings target by a chosen date.
Open Savings Goal Calculator
Retirement Calculator
Connect retirement contributions, a target income, and a long term time horizon.
Open Retirement Calculator
FIRE Calculator
Estimate the savings target and timeline behind a financial independence plan.
Open FIRE Calculator
Rates
Translate rates, inflation, and cash flow into comparable figures.
5 calculators
Simple Interest Calculator
Compare straight line interest on a principal without reinvesting earlier interest.
Open Simple Interest Calculator
Inflation Calculator
Translate future prices into today's money using an assumed inflation rate.
Open Inflation Calculator
APY Calculator
Convert a nominal rate and compounding schedule into an effective annual yield.
Open APY Calculator
APR Calculator
Estimate an annual borrowing cost from interest and eligible fees.
Open APR Calculator
Present Value Calculator
Find what a future payment or cash flow is worth at a chosen discount rate.
Open Present Value Calculator
Borrowing
Understand payments, interest costs, and the path out of debt.
3 calculators
Loan Calculator
Estimate monthly payments, total interest, and repayment cost for a loan.
Open Loan Calculator
Mortgage Calculator
Explore a home loan payment schedule with principal, interest, and term inputs.
Open Mortgage Calculator
Debt Payoff Calculator
Compare repayment timelines and interest cost as you change debt payments.
Open Debt Payoff Calculator
Our standards
Transparent tools with clear limits
Every calculator is free to use, processes your financial inputs in your browser, and explains the model behind its results.
Instant projections
Enter your numbers and see results update as you type. No account, no waiting.
Private & transparent
No data leaves your browser. Open methodology, no hidden assumptions.
Education built in
Every calculator includes guides explaining the math behind the numbers.
Learn
The 3 levers that move your outcome
Most compound calculators spit out a number. We also explain the "why" so you can question your assumptions and learn which levers matter for compound interest growth.
Rate
Small changes compound. Model realistic ranges rather than headline best case numbers.
Time
Years matter more than timing. Run long horizons to see the curve bend.
Cashflow
Deposits and withdrawals change everything. Compare SIP vs SWP scenarios.
Not sure where to begin?
Follow this learning path from basic to advanced.
Topic hubs
Build context before choosing an assumption
Use these guide collections to understand the rates, risks, and cash flows behind each calculator input.
- Compounding guidesCompounding is the whole reason a balance grows faster in its last decade than its first. These guides explain the mechanism rather than celebrating it.
- Interest guidesThe same rate can mean several different amounts of money depending on how it is quoted and how often it is applied. These guides cover the difference.
- Investing guidesCompounding describes what money does. Investing is about the conditions under which it gets to do it, which is where most of the outcome is decided.
- SIP guidesA SIP turns investing into a monthly habit rather than a decision you have to keep making. These guides cover how that changes the arithmetic.
- SWP guidesA withdrawal plan is a compounding problem running in reverse, and reverse is where the arithmetic gets unforgiving.
- Forex Compounding guidesCompounding a trading account works exactly like compounding anything else. The difference is that the rate is not given to you, and it can be negative.
Blog
Browse all 50 guidesFeatured financial guides
Start with practical explanations of compound interest, doubling time, and regular investing.
Compounding
What Is Compound Interest and How Does It Work?
Compound interest grows both principal and previously earned interest. Learn the formula, examples, and key assumptions.
Read What Is Compound Interest and How Does It Work?
Compounding
The Rule of 72 Explained: How Fast Will Your Money Double?
Use the Rule of 72 to estimate doubling time and understand where the shortcut becomes less reliable.
Read The Rule of 72 Explained: How Fast Will Your Money Double?
SIP
How to Start SIP Investing: Step by Step Guide for Beginners
A practical guide to setting a contribution, choosing assumptions, and reviewing a long term SIP scenario.
Read How to Start SIP Investing: Step by Step Guide for Beginners
FAQ
Common questions about compounding
Short answers to what people ask most about these calculators and the maths behind them.
What is compound interest?
Compound interest is when you earn interest on both your original principal and the accumulated interest from previous periods. Because each period's gain becomes part of the balance that earns the next period's interest, growth accelerates the longer you stay invested.
How does the SIP calculator work?
Our SIP calculator estimates the future value of systematic investment plan contributions with compound interest. Enter your monthly SIP amount, expected return rate, and investment duration, and it projects the balance contribution by contribution so you can see how much of the final figure came from deposits and how much came from returns.
What is SWP monthly income?
A systematic withdrawal plan lets you take a fixed amount from your investment corpus at regular intervals while the remaining balance keeps earning compound returns. Our SWP calculator shows how long a corpus lasts at a given withdrawal rate, which is the central question in retirement planning.
How do you compound forex profits?
Forex compounding means reinvesting trading profits so that position size grows with the account. Our forex compound calculator projects account growth from a per trade or per period return. Treat the output as arithmetic rather than a forecast, since real trading returns vary widely between periods.
What is the difference between simple interest and compound interest?
Simple interest is calculated only on the original principal, so it grows in a straight line. Compound interest reinvests each period's gain, so the balance curves upward over time. On a long horizon the gap between the two becomes substantial, which is why the distinction matters more for retirement money than for a short term deposit.
How accurate are compound interest calculator projections?
The arithmetic is exact for the inputs you enter: rate, time, compounding frequency, and contributions. Accuracy as a forecast is a different question. Real returns vary with fees, taxes, inflation, and market volatility, so treat any projection as a model of one scenario rather than a prediction of your actual balance.
Ready to model your financial growth?
Start with compound growth, compare contribution and withdrawal scenarios, or learn how each model works. Every calculator is free and keeps your inputs in your browser.
Educational use only. Results are estimates and may not reflect fees, taxes, spreads, or execution.