Free guides

Plain, step-by-step answers to everyday file and number questions: how to get a photo under 50 KB, merge PDFs, convert HEIC or work out an EMI. Each one ends with a free tool that does the job in your browser.

Calculators guides

• Amortization Schedule Explained: How to Read One (Free)An amortization schedule shows how each loan payment splits between interest and principal. Why early payments are mostly interest; try a free loan calculator.
• APR vs Interest Rate: What's the Difference? (Free)The rate sets your payment; the APR adds fees to show the true yearly cost. See how a $600 fee turns 7.5% into 8.8% APR, using a free loan calculator.
• Best Pomodoro Apps Compared: Which One Suits You?Forest, Pomofocus, Focus To-Do, Be Focused, Toggl Track and our free Focus Timer compared: what each Pomodoro app is for and who it suits.
• Binary to Decimal: How to Convert by Hand (Free Tool)To convert binary to decimal, add the place values (1, 2, 4, 8…) wherever there's a 1. 1011 = 11. Worked examples, the reverse method and a free converter.
• How to Calculate Age from Date of Birth (Free)Enter a date of birth to get an exact age in years, months and days, or an age on any cut-off date for exam and job forms. Free age calculator.
• Attendance Calculator: Your % and Classes to Bunk (Free)Attendance % = classes attended ÷ classes held × 100. See how many classes you can miss, or must attend, to stay at 75%, with a free calculator.
• How to Calculate Days Between Two Dates (Free)Count the days, weeks, months and weekdays between two dates, or add days to a date to find a deadline. Free date calculator, with examples.
• How to Calculate Discount Percentage (Free Calculator)Sale price = price × (1 − discount ÷ 100). Discount % = (original − sale) ÷ original × 100. Plus why 20% + 10% off is only 28%, with a free calculator.
• How to Calculate EMI: Formula and Free EMI CalculatorEMI = P × r × (1 + r)^n ÷ ((1 + r)^n − 1). See a worked example for a home loan and a personal loan, then check your own with the free EMI calculator.
• How to Calculate a Mortgage Payment (Free Calculator)Use M = P × r ÷ (1 − (1 + r)^−n) for principal and interest, then add tax, insurance, HOA and PMI. Worked example and a free mortgage calculator.
• Notice Period Calculator: Find Your Last Working Day FreeWork out your last working day from your resignation date for a 30, 60 or 90-day or one-month notice period, with the free date calculator and examples.
• How to Calculate Percentage Increase and Decrease FreePercent change = (new − old) ÷ old × 100. Worked examples for prices, salaries and marks, plus the common traps, and a free calculator.
• How to Calculate Percentage of Marks (Free Calculator)Add up your marks, divide by the maximum marks and multiply by 100. 432 out of 500 is 86.4%. Examples for subjects, totals and CGPA, plus a free calculator.
• How to Calculate Percentage: 3 Formulas (Free Calculator)Find X% of a number, what percent one number is of another, and the percent change between two values, with formulas, examples and a free calculator.
• Salary Hike Calculator: Hike % and New CTC (Free)Hike % = (new CTC − old CTC) ÷ old CTC × 100. Work out your new CTC from a hike, and a rough monthly change, with a free percentage calculator.
• How to Calculate Sales Tax and Back It Out (Free)Sales tax = price × rate ÷ 100. To find the pre-tax price from a total, divide by 1 + the rate. US examples, local rate tips and a free calculator.
• Car Loan EMI Calculator: Down Payment and Tenure (Free)Work out your car loan EMI from the on-road price, down payment, rate and tenure with the free EMI calculator. See how 3, 5 and 7 years change the interest.
• CGPA to Percentage: Which Formula to Use (Free)CBSE used CGPA × 9.5, but universities set their own formulas. See why 8.4 can mean 76.5% or 84%, and work out yours with a free percentage calculator.
• How to Convert Fractions to Decimals (Free Converter)To turn a fraction into a decimal, divide the top number by the bottom. See worked examples, repeating decimals, a common-fractions chart and a free converter.
• Business Days Calculator: Count Working Days FreeCount the business days (Monday to Friday) between two dates with the free date calculator, then subtract public holidays yourself. Worked examples.
• When Does Daylight Saving Time End? 2026-27 Dates (Free)US clocks go back 1 November 2026; the UK and EU changed 25 October. All 2026 and 2027 dates, why India has no DST, and a free time zone converter for any city.
• Education Loan EMI Calculator: Moratorium Explained (Free)How the moratorium, interest during study and disbursements change your education loan EMI, with a worked example you can check in the free EMI calculator.
• EMI Formula in Excel: PMT Function + Free CalculatorCalculate EMI in Excel or Google Sheets with =PMT(rate/12, months, -loan). Worked example, a monthly schedule, common mistakes, and a free calculator to check.
• SIP Calculator: Estimate SIP Returns Free (Worked Examples)Estimate a monthly SIP's growth free with an assumed return. ₹5,000 a month at 12% for 10 years is about ₹11.5 lakh. Returns are not guaranteed.
• Extra Mortgage Payments: How Much You Save (Free)One extra mortgage payment a year can cut a 30-year loan by over 5.5 years and save about $89,600 in interest. See the maths and run your own free.
• FD Calculator: How FD Interest Is Calculated (Free)Most bank FDs compound quarterly: A = P × (1 + r/4)^(4t). ₹1 lakh at 7% for 5 years matures at about ₹1,41,478. Examples, TDS and a free calculator.
• Flat vs Reducing Interest Rate: The Real Cost (Free)A 10% flat rate costs about the same as an 18% reducing rate on a 3-year loan. See why, convert one to the other, and check offers with a free EMI calculator.
• Half Birthday Calculator: Find the Date FreeA half birthday is six months after your birthday. Find the exact date with the free date calculator, including tricky ones like 31 August and 29 February.
• Height in cm: Feet and Inches to cm Chart (Free)Convert your height from feet and inches to cm, or cm back to feet. 5'6" is 167.6 cm. A chart of common heights and a free unit converter.
• Hexadecimal Explained: Base 16 Made Simple (Free)Hexadecimal is base 16, using 0-9 and A-F. Why it's used for colours, memory and MAC addresses, how to convert it by hand, and a free converter.
• Home Loan EMI vs Tenure: Shorter or Longer? (Free)A longer home loan tenure lowers your EMI but can more than double the interest. Compare 10 to 30 years on a ₹30 lakh loan, then try the free EMI calculator.
• Home Loan Prepayment Calculator (Free): EMI or Tenure?A part-prepayment cuts your home loan interest. See why reducing the tenure saves more than reducing the EMI, with a free EMI calculator example.
• How Compound Interest Works (Formula + Free Calculator)Compound interest earns interest on your interest. See the formula A = P(1 + r/n)^(nt), worked examples, the rule of 72 and a free calculator.
• How Many Days Old Am I? Free Age in Days CalculatorEnter your date of birth to see your age in days, weeks and months, then find the date you turn 10,000 days old. Free, nothing to sign up for.
• How Many Weeks in a Year? 52 or 53 (Free Tool)A year has 52 weeks plus 1 day (2 in a leap year). Why some years have 53 weeks and what that means for pay periods; check yours with a free week number tool.
• How Much to Tip: Free Tip Calculator and Customs GuideHow much to tip depends on the country and the service. Learn the usual ranges, the simple tip formula, and split the bill with a free tip calculator.
• How Old Will I Be in 2030? Free Future Age CalculatorSubtract your birth year from 2030 for the age you turn that year, or enter any future date in the free age calculator for your exact age then.
• IST to EST: Time Difference and Best Call Hours (Free)India is 10h 30m ahead of US Eastern in winter and 9h 30m ahead in summer. Conversion table, switch dates, overlap hours, and a free time zone converter.
• Korean Age Explained: Korean vs International AgeTraditional Korean age starts at 1 and rises every 1 January. South Korea switched to international age in June 2023. Formulas, examples and a free calculator.
• Leap Year Rules: Which Years Are Leap Years?A leap year is divisible by 4, except century years, which must be divisible by 400. See the next leap years and check any year with a free date calculator.