Calculator guides

Short, practical explanations of the numbers behind our most-used calculators.

• 7 min read · Finance

  How to Calculate Zakat in Pakistan (2026)

  What counts as zakatable wealth, how the silver and gold nisab work in rupees, what to deduct, and a worked example of 2.5% zakat on cash and gold.

• 6 min read · Finance

  Home Loans in Pakistan: How Instalments Work

  How banks calculate home-loan instalments, why KIBOR resets change your payment, how much down payment you need, and how to cut the total interest.

• 4 min read · Finance

  How to Add or Remove 18% GST

  The right way to add 18% sales tax to a price and to take it out of a tax-inclusive total — and the common mistake that gives the wrong answer.

• 4 min read · Converters & Everyday

  Petrol Cost per Km: Plan Any Trip's Fuel Bill

  How to find your car's real fuel average, work out petrol cost per kilometre and estimate the fuel bill for trips like Lahore to Islamabad.

• 5 min read · Health & Fitness

  Pregnancy Due Date: How It Is Calculated

  How doctors estimate your due date from your last period, why pregnancy is counted as 40 weeks, how cycle length changes it, and what the trimesters mean.

• 6 min read · Property

  Marla, Kanal & Acre Explained (Pakistan)

  Why a Marla can be 272.25, 250 or 225 square feet, how Kanal and acres relate, and how to avoid costly mix-ups when buying property.

• 5 min read · Education

  How to Calculate GPA and CGPA (with Examples)

  A step-by-step guide to quality points, semester GPA and cumulative CGPA, and why simply averaging your semester GPAs can be wrong.

• 5 min read · Electricity & Solar

  How to Estimate Your Electricity Bill

  Turn watts and hours into units, find your real rate per unit from your bill, and see which appliances matter most in a Pakistani home.

• 6 min read · Electricity & Solar

  How Many Solar Panels Do I Need? (Pakistan)

  Size a home solar system from your electricity bill, understand peak sun hours and efficiency, and estimate payback.