About NumberPilot

What this site is

NumberPilot offers 10 calculators covering the money decisions people actually face — mortgages and loans, compound interest and retirement, salary and take-home pay, credit card payoff, inflation, and everyday maths like tips and percentages.

Each one gives you more than a single figure. You get the breakdown behind the result, a chart of how it changes over time, a full amortization or projection schedule where that applies, the formula used, a worked example, and answers to the questions people usually ask next.

How the calculations work

Every calculation runs inside your browser in JavaScript. Your numbers are never sent to us, because there is no server to send them to — this is a set of static files.

That has a few practical consequences we think are worth stating plainly:

• Results appear as you type, with no page reloads and no waiting.
• Your figures are not logged, stored, sold, or used to profile you.
• The site works on a slow connection, and keeps working if you lose signal after the page loads.

The formulas are the standard ones used across the finance industry — amortizing payment formulas for loans and mortgages, periodic compounding for savings and investment growth, and straightforward arithmetic elsewhere. Each calculator page spells out the specific formula it uses under "How it's calculated".

Accuracy and limitations

These are estimates, and estimates are only as good as their assumptions. Real-world figures differ for reasons a calculator cannot know: lender fees and closing costs, the exact compounding and day-count conventions your bank applies, tax brackets and local rules, rate changes on variable products, and rounding at each step of a real amortization schedule.

Use these tools to understand the shape of a decision and compare options against each other. Use your lender, accountant, or a licensed adviser for the number you actually sign.

Where a calculator makes a simplifying assumption, the page says so. Corrections are genuinely welcome, and we would rather fix a formula than defend it.

How the site is funded

NumberPilot is free to use and does not require an account. The site is supported by advertising, which is what keeps every calculator open to everyone with no paywall or signup.

Advertising never influences the maths. The formulas are standard and public, and no advertiser has any say over a result, a recommendation, or which calculators exist. We do not accept payment for placement inside calculator results.

What advertising means for your data is set out in the privacy policy.

Who builds it

NumberPilot is an independent project, not a bank, broker, lender, or financial institution. We do not sell financial products, take commissions on them, or refer you to anyone in exchange for payment.

That independence is the point: the calculators exist to help you think, not to move you toward a product.