A calculator is only useful if you can trust it. This page explains how we build and maintain ours.
We start from the official rule
Every calculator is based on a published source, which we name on the calculator's page: the Finance Act for Pakistan salary tax, Federal Decree-Law No. 33 of 2021 for UAE gratuity, accepted fiqh guidance for zakat, and standard mathematical formulas for loans, percentages and unit conversions.
We show the working
Every result comes with the steps used to reach it, so you can check the calculation yourself or show it to someone else. If a step looks wrong, you can tell us exactly where.
We test with worked examples
Before a calculator goes live, we check it against hand-worked examples, including edge cases such as the start of a new tax slab, service under one year, or a zero interest rate. The examples on each page are the same ones we test with.
We update when rules change
After each federal budget, labour law change or similar update, we review the affected calculators and guides and change the “last checked” date. Guides also show the date they were last updated.
We fix mistakes quickly
If you find an error, please contact us with the numbers you used and, if possible, a link to the official source. We aim to review reports within two working days and correct confirmed mistakes straight away.
Independence
Sumtrail is funded by advertising. Advertisers do not see our content before it is published and have no say in how our calculators work.