Investment Calculator

How to use Investment Calculator

1. Open Investment Calculator in your browser — it loads instantly and works offline once cached.
2. Enter your values in the input fields. Every field is labelled so you know exactly what to type.
3. The result updates automatically as you type — there is no "submit" round-trip to a server.
4. Adjust any input to compare scenarios and see how the outcome changes in real time.
5. Copy or note the result. Nothing you enter is stored or sent anywhere.

Why use Investment Calculator?

• 100% free with no limits, no sign-up and no watermarks.
• Private by design — your data are processed in your browser and never uploaded to a server.
• Fast and lightweight, with instant results even on a phone or a slow connection.
• Works everywhere — any modern browser on Windows, macOS, Linux, Android or iOS.
• Part of a full financial calculators suite, so related investment tasks are one click away.

What people use Investment Calculator for

• Projecting a portfolio's value from regular contributions over time.
• Comparing outcomes at different assumed rates of return.
• Estimating what you need to contribute to reach a target.

Investment Calculator: limits and things worth knowing

• Regular contributions dominate early and compounding dominates later. £300 a month for 30 years at 7% reaches about £340,000, of which £108,000 is contributions.
• The assumed rate is the whole projection. Dropping 7% to 5% on that example removes roughly £90,000 — which is why a single projected figure is misleading without a range.
• Real returns are not smooth. A sequence of poor years early in a withdrawal phase does far more damage than the same years later, an effect an average return cannot show.
• Figures are nominal. At 2.5% inflation, £340,000 in 30 years has roughly the purchasing power of £162,000 today.

Is it private and secure?

Your privacy is built in. Investment Calculator runs completely on your device, so whatever you enter stays in your browser and is never transmitted, logged or stored on any server.

Network activity: none. Nothing is sent and nothing is fetched. This tool makes no network request at all once the page has loaded — which is why it keeps working if your connection drops.

You do not have to take that on trust — our privacy proof page publishes the Content-Security-Policy that enforces it, lists every third party it permits, and shows how to verify the whole claim yourself.

Learn more

Why Browser-Based Tools Are Safer for Your Files — Most online converters upload your files to a server. Client-side tools don't. Here's why that difference matters for privacy.