About Reliable Calculator

Reliable Calculator is a free collection of online calculators and plain-English guides for the numbers that come up in everyday life: paychecks and taxes, loan and mortgage payments, savings goals, calorie targets, percentages, dates, home projects and unit conversions.

Why this project exists

Most people meet an important number at an inconvenient moment: a job offer quoted as an annual salary, a lender's monthly payment, a recipe in grams, a contractor's estimate in square feet. Search for a calculator and you often get a page buried under pop-ups, a tool that asks for an email address before showing the answer, or a bare result with no explanation of where it came from.

Reliable Calculator was started to fix that. The goal is simple: give a correct answer quickly, then show exactly how it was worked out, so you can trust it, check it and explain it to someone else.

What we try to do differently

The answer comes first. Results appear as you type. There is no sign-up, no email gate and no "premium" version.
Every result is explained. Each calculator lists its formula, walks through a worked example with real numbers, and points out the assumptions it makes.
Current, sourced figures. Tax brackets, standard deductions, contribution limits and state rates come from official publications such as the IRS and state revenue departments, and are reviewed when new figures are released each year.
Quick-reference pages for common questions. Questions like "what is $25 an hour a year?" or "how many kg is 150 lbs?" have their own pages with the answer, the working and a comparison table, so you do not have to set up a calculator for a single number.
Several languages. The most widely used tools are also available in Spanish, German and Turkish, adapted to local rules such as VAT rates and payroll deductions rather than simply translated.

What we believe

Show the working. Every calculator explains its formula and includes a worked example, so you can check the result and understand where it comes from.
Respect your privacy. Calculations run in your browser. We do not ask you to sign up, and we do not store the figures you type in.
Keep it fast. Pages are lightweight and work well on phones and slow connections.

Read our editorial policy and methodology for the sources we use and how every tool is tested.

How our calculators are built

Each tool is based on a standard, published method: the amortization formula used by lenders, the Mifflin-St Jeor equation recommended by dietitians, the US Navy body fat method, the Gregorian calendar rules for dates, and internationally defined conversion factors. We test each calculator against hand-worked examples and reputable reference sources before publishing, and we review pages regularly.

Corrections and suggestions

If you spot an error or want a calculator we do not have yet, please contact us. Many of our tools started as reader suggestions.

How the site is funded

Reliable Calculator is free to use and is supported by advertising. Advertisers have no influence over our content or results.

Important note

Our tools provide estimates for general information and education. They are not a substitute for advice from a qualified financial adviser, doctor, lawyer or other professional who knows your circumstances.