About Reckonly — How We Build Our Calculators

About

About Reckonly

Free, accurate, formula-first calculators for finance, health, and everyday decisions — built for people who want to understand their numbers, not just get an answer.

Why Reckonly Exists

Most online calculators give you a number and nothing else. No formula, no explanation of what was assumed, no way to verify the answer. You're expected to trust a result you can't check.

Reckonly was built on one principle: every result must be verifiable. Every calculator on this site shows the exact mathematical formula used, defines every variable, and displays a worked example with real numbers. If you can't check the math yourself, we haven't done our job.

The second principle is privacy. Financial questions — income, loan amounts, savings balances, health data — are private. Every calculation on Reckonly runs entirely in your browser. No numbers you enter are transmitted to any server, stored in any database, or shared with any third party.

What We Build

💰
Finance Calculators

Mortgage, loan EMI, compound interest, savings goals, US income tax 2025, retirement planning, tip splitting, and live currency conversion.

📏
Everyday Calculators

BMI, age, date difference, unit converter, discount, percentage, and fuel cost — tools for daily decisions that require accurate numbers fast.

📐
Formula-First Design

Every tool publishes the full formula, variable definitions, and a worked example verified against the live calculator before publishing.

Who Builds This

👨‍💻
Saif Khan
Founder, Reckonly

I built Reckonly because I kept finding calculator websites that gave answers without showing their work. As someone with a background in software development and a strong interest in personal finance, I know how much the formula matters — especially for decisions like mortgages, retirement savings, and tax planning.

Every calculator on this site is built, tested, and verified by me personally. I check every formula against primary sources — IRS publications, WHO standards, ECB rate data — and test every tool against multiple known inputs before it goes live.

Reckonly is an independent project. No investors, no ads, no monetization pressure. Just clean, accurate tools built to help people make better decisions with numbers.

How We Ensure Accuracy

Every calculator on Reckonly passes a strict pre-publish checklist before going live:

1
Formula verified against a primary source

IRS publications for tax brackets, WHO documentation for BMI, ECB for currency rates, standard finance texts for amortization — never a secondary blog or competitor site.

2
Worked example confirmed against the live tool

Real numbers are entered into the calculator and the output is confirmed to match the manually calculated result. This is a release gate — not optional.

3
Edge cases tested

Zero values, empty inputs, very large numbers, negative values, and date boundaries are all tested before any tool is published.

4
Annual review schedule

Tax brackets are updated every year when the IRS publishes new figures. Currency rates are live from ECB. All updates are logged in the Changelog with dates.

Our Commitments

🆓
Free Forever

All 15 tools are free. No subscription, no freemium, no paywalls.

🔒
Privacy First

No data collected. All calculations stay in your browser.

📐
Formula Shown

Every result includes the full formula and worked example.

Verified Sources

IRS, WHO, ECB — official primary sources only.

Contact & Corrections

Found an error in a formula or result? Please report it. Accuracy is the entire point of this site, and corrections are taken seriously and fixed promptly.

📧 Use the Contact page to report errors, suggest improvements, or ask questions about how a calculation works. Every message is read personally.

See also: Methodology · Sources · Changelog · Privacy Policy

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