About CheckMySum

CheckMySum is a free set of calculators for pay, tax and savings. It has 25 calculators for workers in the United States and the United Kingdom. There is no account to create and nothing to download.

Why this site exists

Most pay questions have a simple answer that is hard to find. How much of my overtime is tax-free? What is my salary per hour? What will my savings be worth in ten years? Many calculators give a number and nothing else, so you cannot tell if the number is right.

Every calculator here shows its working. You see the formula, a worked example, and a link to the official rule the figures come from. If you disagree with a result, you can check each step.

How each calculator is built

  1. Start from the official source. Tax rates, limits and thresholds are read from the body that sets them: the IRS, the Social Security Administration and the Department of Labor in the US, and HMRC and gov.uk in the UK. Each page lists the sources it used.
  2. Write the maths and test it. Each calculation is checked against examples worked by hand, including the awkward cases where a limit or threshold applies.
  3. Generate the examples from the same maths. The worked examples and tables in each article are produced by the same code as the calculator, so the text and the tool cannot disagree.
  4. Date it. Each page shows when its figures were last checked. Tax figures are updated when the new year's figures are published.

What the calculators are not

The results are estimates for planning. They cannot know everything about your situation, and they are not tax, legal or financial advice. For a decision that matters, check the official source or speak to a qualified adviser. The disclaimer explains this in full.

Your privacy

The numbers you type into a calculator stay in your browser. They are not sent to us or stored. The privacy policy explains what the site does collect.

Who runs it

CheckMySum is run by CheckMySum, based in 427, KBC-1, Karunesh Business Center, opposite Abhishek Arcade, Yogi Chowk Ground, Chikuwadi, Nana Varachha, Surat, Gujarat 395011, India. If you find a mistake or want a calculator added, tell us. Corrections are checked against the official source and fixed.