How to Add and Subtract Time (Hours, Minutes, Seconds)
Learn how to add and subtract time in hours, minutes and seconds, carry over 60 minutes, handle times past midnight and convert to decimal hours.
Calculators guides
Guides, tips and worked examples for our free calculators. Every article links to the tool it explains.
How to Calculate Days Between Two Dates (and Weeks, Months)
Learn how to calculate the number of days between two dates by hand or online, including or excluding the end date, plus weeks, months and working days.
How to Calculate Profit Margin: Formula and Examples
Learn how to calculate profit margin from cost and selling price, the difference between gross and net margin, and how to set prices that hit a target margin.
Compound Interest Formula Explained With Simple Examples
The compound interest formula explained in plain English, with step-by-step examples, monthly vs yearly compounding and how to calculate growth with deposits.
Gross vs Net Salary: What You Earn and What You Take Home
Understand gross vs net salary: what deductions come out of your pay in Pakistan, how to read your payslip and how to work out your real take-home income.
How to Calculate Discount and Sale Price (With Examples)
Learn how to calculate discount amount and final sale price from a percentage, find the discount rate from two prices, and handle extra discounts correctly.
What Is an Amortization Schedule? Read Your Loan Month by Month
An amortization schedule shows how each loan payment splits into interest and principal. Learn to read one, spot key turning points and use it to save money.
How to Calculate BMI: Formula, Chart and Examples
Learn how to calculate BMI in kg and cm or pounds and inches, read the BMI chart, and understand what your result means, with simple worked examples.
How to Calculate CGPA From Semester GPAs (Step by Step)
Learn how to calculate CGPA from your semester GPAs and credit hours, with a worked example, common mistakes and tips for checking your transcript.
How to Calculate GPA: Credit Hours, Grade Points and Examples
Learn how to calculate your semester GPA step by step using credit hours and grade points on the 4.00 scale, with a worked example and common mistakes.