Editorial policy

This page explains how we decide what a calculator should do, how we make sure it gives the right answer, and what happens when someone finds a mistake.

How a calculator is built

1. Define the question and the method. We write down exactly what the calculator answers and which formula, rule or published standard it follows, with the source.
2. Write the math on its own. The calculation is written as a small, separate piece of code with no connection to the page design, so it can be tested directly.
3. Test it against known answers. Before a page goes live, the math must reproduce a set of answers taken from outside sources or worked out by hand, including awkward cases such as leap years, overnight shifts and values at the edge of a threshold. These tests run again every time the site is updated, and a failing test stops the update from being published.
4. Explain it in plain language. Each page describes the method, walks through a worked example with real numbers, and shows your own numbers in the formula as you use it.
5. Review before publishing. The page, the example and the results are checked before the calculator is added to the site.

Sources we rely on

• Tax rates: figures published by the Tax Foundation, with the date they were last checked shown on the page.
• Building materials: the yields and coverage that manufacturers print on their products.
• Calendars: the Umm al-Qura calendar for Hijri dates, the standard Western and Orthodox methods for Easter, and the traditional Chinese lunisolar calendar for the zodiac.
• Everything else: the underlying arithmetic, shown in full on each page so it can be checked.

Religious calculators

Zakat, Hijri dates, Easter dates and similar tools touch on religious practice, and communities do not always follow the same method. For these calculators we:

• state the method or school of thought used, near the calculator itself
• let you choose where recognized methods differ, such as the gold or silver nisab for zakat
• note where local practice can change the result, such as moon sighting for Hijri dates
• use neutral, respectful language and do not favor one tradition over another
• make clear that results are a guide, not a religious ruling, and suggest consulting a qualified scholar or your local religious authority

When a qualified reviewer has checked a calculator, the page shows a "Reviewed by" line with their name. We only show that line when such a review has actually taken place.

Keeping pages up to date

Every calculator page shows the date it was last updated. Figures that change over time, such as sales tax rates, are re-checked against their source when new figures are published, and the page shows the date of the last check.

Corrections

Every calculator page has an "Is this result wrong?" link. You can also email hello@infinitecalculators.com or use our contact page. Tell us the page, the values you entered and the result you expected. We repeat your calculation, and if the site is wrong we fix the math, add your case to the tests so the mistake cannot return, and update the page date.

Advertising and independence

The site is paid for by advertising. Advertisers have no influence over which calculators we build, how they work or what they say. Infinite Calculators is owned and operated by IdeoXpert.