How-to guides & comparisons
Step-by-step guides for everyday file and number tasks — merging PDFs, shrinking photos, converting HEIC, loans, passwords and more.
Equal Payments vs Equal Principal: Loan Repayment Types
Compare equal payments, equal principal and interest-only loans, see how total interest differs, and test your own scenarios with a free loan calculator.
Exact Age Calculator Guide: Years, Months and Days
Learn how to calculate your exact age in years, months and days by hand, handle leap-day birthdays, and count days lived or days until your next birthday.
How to Add or Remove VAT from a Price (With Formulas)
Learn the simple formulas to add VAT to a net price or remove it from a gross price, avoid the common subtraction mistake, and round amounts correctly.
How to Convert HEIC to JPG on Windows, Android and Mac
Can't open iPhone HEIC photos? Learn what HEIC is and how to convert HEIC to JPG on Windows, Android or Mac — free, in your browser, with no uploads.
How to Create a Strong Password (and Keep Track of It)
Learn how to create a strong password: why length matters, patterns to avoid, passphrases, password managers and 2FA, plus a free random password generator.
How to Merge PDF Files for Free: 4 Methods Compared
Compare free ways to merge PDF files—online tools, Mac Preview, Windows and Acrobat—then combine PDFs in your browser without uploading them.
How to Reduce Image File Size for Email and Uploads
Photo too big to send or upload? Learn how compression, resizing and the right format (JPG, PNG or WebP) shrink images to any size limit, right in your browser.
How to Split, Delete and Reorder PDF Pages (Free, No Upload)
Learn which free tool to use to split, delete, reorder or rotate PDF pages, how page ranges like 1, 3, 5-7 work, and how to do it all in your browser.
PDF to JPG and JPG to PDF: How and When to Convert
Learn when to turn a PDF into JPG images and when to combine photos into one PDF, how to pick dpi and page order, and how to convert in your browser.
Unit Conversion Cheat Sheet: Length, Weight, Area & Temperature
Key conversion factors for inches, feet, miles, pounds, ounces, square feet, acres and °C/°F, plus US vs UK gallons and cups, and common mistakes to avoid.