Compound Interest and SIP Calculator

📖 Tool Introduction

Compound interest means the interest itself earns interest, and the gap widens the longer you wait. At eight percent the same sum roughly doubles in ten years and comes close to tenfold in thirty.

This calculator handles both kinds of contribution at once: a lump sum at the start and a fixed amount every month, rolled forward at the compounding frequency you choose.

Besides the forward projection it also solves backwards: give it a target and it reports how many years it takes to get there.

Every figure you type stays inside this browser tab. The arithmetic runs as plain JavaScript on your own device, so nothing is uploaded to a server, nothing survives after you close the page, and there is no account to create or sign in to. You can enter real numbers without worrying about them leaving your machine.

What comes out is a mathematical projection built on the assumptions you supply, and the assumptions are the part worth checking. Real outcomes turn on details no calculator can see: the exact wording of a loan contract, the policy in force in your city this year, the way your own body responds. Use these numbers to orient yourself and to compare one option against another, then confirm anything that carries real consequences against an official document or a professional who can look at your actual circumstances rather than a generic formula. Where a result feeds into a decision that costs money or affects your health, treat it as the opening of a conversation with someone who can see the whole picture rather than as the answer in itself.

The inputs here are deliberately plain: no file to upload, no network call, no queue to wait in. That keeps the tool fast and private, and it also means no record exists anywhere of what you calculated, so nothing you try here can come back to you later.

✨ Key Features

• Lump sum and monthly contribution calculated together
• Three compounding frequencies: monthly, quarterly and annual
• Final value, total invested, net gain, return rate and multiple
• Inflation adjustment showing real purchasing power
• Target solving: enter a goal and get the years required
• Recalculates the moment you change any figure, with no waiting and no separate submit step

🚀 How to Use

1. Enter the initial amount and the monthly contribution, or zero if none
2. Enter the expected annual return and the number of years
3. Choose the compounding frequency; contributions default to monthly and a higher frequency yields slightly more
4. Enter an inflation rate if you want the purchasing power figure
5. Enter a target amount on the right to solve for the years needed

⚠️ Things to Note

• The return is an assumption: The annual return is an assumption. Real investments fluctuate year to year, and the long-run average is not what any single year delivers
• Fees are not included: This tool ignores subscription, management and redemption fees plus taxes, so actual proceeds will be lower
• Not investment advice: Past annualised returns do not predict future ones. This is a mathematical projection, not investment advice
• Computed locally in your browser: Every figure is worked out inside your own browser and nothing is sent to a server. The values disappear when you close the page, so you can safely enter real numbers
• Indicative results only: What you see here is a mathematical projection. For contracts, tax filings or medical decisions, rely on the official documents issued by the relevant authority rather than on this tool