Editorial and corrections policy

How Calculator786 calculators are written, checked and kept current. Last updated: October 2026.

What every calculator page includes

Each calculator shows its formula, the assumptions and limits it uses, a worked example computed by the same engine you use, and frequently asked questions. Where accuracy depends on law, official rates or a published standard, the page links to the official source and states the tax year or edition it follows.

How calculations are checked

Every formula is covered by automated tests with hand-checked boundary cases. Calculators are also compared against reference calculations written independently in a second programming language, across thousands of generated inputs; a disagreement blocks publication. Unit conversions use exact legal definitions, such as 1 inch = 2.54 cm.

Review dates and updates

Each calculator page shows the month it was last reviewed. Tax calculators are re-verified against the official schedules before each new tax year, and the tax year is named in the page title. When an official rule changes, the calculation, its tests and its explanation are updated together.

Sensitive topics

Tax, money, health and religious calculators give estimates for the inputs and assumptions shown; they are not professional, medical, legal or religious advice. Where qualified opinion differs, such as nisab conventions for zakat, the page explains the options and lets you choose.

Corrections

When an error is found, the calculation is fixed, a test reproducing the error is added so it cannot return, and the page’s review date is updated. Material changes to a tax or rate schedule are reflected in the page’s explanation and sources.

Independence

Calculators are not sponsored, and no result is influenced by an advertiser. If advertising is shown, it is labelled, kept away from calculator controls and never receives calculator inputs. See the privacy notice and about page.