Guides
Step-by-step guides for everyday document, image and data tasks.
- Base64 explained: what it is, when to use it and when not toHow Base64 turns binary data into text, why it makes files 33% larger, the difference with Base64URL, and why it is not encryption.1 min read
- Celsius to Fahrenheit Formula (and Fahrenheit to Celsius)The exact formulas to convert Celsius to Fahrenheit and back, worked examples, a quick mental shortcut, a table of common temperatures and how Kelvin fits in.3 min read
- DPI explained — what resolution you actually needWhy 72 dpi is a myth on screens, what 300 dpi means for printing, and how to work out the pixel dimensions you need from a physical size.3 min read
- How loan and mortgage interest works (and how to pay less)Understand monthly payments, amortization and total interest on fixed-rate loans, and see how term length and extra repayments change what you pay.2 min read
- How to add a watermark to a PDF or a photoStamp CONFIDENTIAL, DRAFT or your name on a PDF or on photos, choose the right size and opacity, and know how much protection a watermark really gives.3 min read
- How to add page numbers to a PDFNumber the pages of a PDF in your browser, choose the format and position, skip the cover page, and avoid numbering mistakes when combining files.3 min read
- How to Calculate Age and Days Between Two DatesWork out an exact age in years, months and days, count the days between two dates, handle leap years and count working days without off-by-one errors.3 min read
- How to Calculate Compound Interest (Formula + Examples)Learn the compound interest formula A = P(1 + r/n)^(nt), how compounding frequency and monthly contributions change the result, and the rule of 72.3 min read
- How to calculate percentages (with the formulas you actually need)The four percentage calculations everyone uses — X% of Y, what percent, percentage change and reverse percentages — with worked examples and common traps.1 min read
- How to Change Uppercase to Lowercase (and Back)Change text from uppercase to lowercase in Word, Google Docs and Excel, learn title vs sentence case, and create camelCase or snake_case names.3 min read
- How to check and remove GPS location from photos before sharingPhotos often contain the exact place they were taken. Learn how to see this hidden EXIF data and strip it before posting or sending pictures.1 min read
- How to clean up text copied from a PDF or websiteFix broken lines, double spaces, curly quotes, invisible characters and leftover HTML in text copied from PDFs, emails and web pages.1 min read
- How to compare two versions of a text and see exactly what changedSpot the real differences between two drafts, two contracts or two API responses — including the invisible changes that cause the most trouble.2 min read
- How to convert a PDF to JPG (every page or just one)Turn PDF pages into JPG images in your browser, pick the right DPI for screen or print, and know when PNG is the better choice for text.3 min read
- How to Convert Hourly Pay to Annual SalaryConvert an hourly wage into a yearly, monthly or weekly salary and back, using your real hours and paid weeks, with worked examples and overtime.3 min read
- How to convert WebP to JPG (or PNG)Why images saved from websites end up as .webp, why some apps and forms refuse them, and how to convert them to JPG or PNG in your browser.3 min read
- How to count words and characters accurately (and why tools disagree)What counts as a word or a character, why Word, Google Docs and social networks give different numbers, and how to hit length limits for essays, SEO and SMS.1 min read
- How to create a strong password you can actually useWhat makes a password strong, why length beats complexity, how passphrases work, and how to store passwords safely with a password manager.1 min read
- How to extract text from a PDF (and when you can't)Pull the text out of a PDF as plain text, understand why scanned PDFs give nothing, and clean up broken lines and spacing before reusing it.3 min read
- How to fill out a PDF form without printing itFill in a PDF form on your computer or phone, lock the answers so they display everywhere, sign it, and know what to do when the PDF has no fields.3 min read
- How to format, validate and fix JSONRead and debug JSON quickly — pretty-print it, find the exact line of a syntax error, understand the most common mistakes and minify it for production.1 min read
- How to make a favicon for your websiteTurn a logo into a full favicon set — favicon.ico, PNG sizes, Apple touch icon and web manifest — and learn where to put the files and what HTML to add.3 min read
- How to make a PDF smaller for email and upload limitsWhy some PDFs are huge, which compression method to choose, and how to reach a target size such as 2 MB or 5 MB without ruining readability.2 min read
- How to make a Wi-Fi QR code guests can scan to connectCreate a QR code that joins your Wi-Fi network in one tap on iPhone and Android, print it well, and keep your network secure.1 min read
- How to merge PDF files (without uploading them)Combine several PDFs into one document in the right order, keep quality intact and avoid the common pitfalls with scans, forms and protected files.2 min read
- How to open a CSV file in Excel without breaking accents and columnsWhy CSV files open with garbled characters or everything in one column, and three reliable ways to get clean data into Excel or back out as CSV.2 min read
- How to password-protect a PDF (and share the password safely)Encrypt a PDF so only the right person can open it, choose a password that holds up, send it without leaking it, and remove it again later.2 min read
- How to prepare a photo for an online application formExam portals, visa sites and job platforms all ask for a photo in a precise format. Here is the order to do things in so it's accepted the first time.2 min read
- How to reduce image file size without losing visible qualityThe three levers that shrink images — dimensions, quality and format — with concrete settings for email, websites and social media.2 min read
- How to remove a password from a PDF (when you know it)Remove the password from a PDF you can already open, lift printing or copying restrictions, and understand the difference between the two kinds of PDF password.3 min read
- How to remove duplicates from a list (emails, keywords, product codes)De-duplicate any list in seconds while keeping the original order, handle case and spacing differences, then sort and clean the result.1 min read
- How to remove the background from an imageRemove the background from a photo in your browser, get a transparent PNG or a plain colour, and fix the edges when the cut-out isn't perfect.3 min read
- How to rotate a PDF and save it permanentlyRotate one page or a whole PDF and save the change for good, so sideways or upside-down scans open the right way for everyone who gets the file.3 min read
- How to sign a PDF without printing itAdd your signature to a PDF on a phone or a computer in two minutes, place it cleanly, and know when a visual signature is enough — and when it isn't.2 min read
- How to split a PDF into separate filesThree ways to split a PDF — by page ranges, every N pages or page by page — and when to extract or delete pages instead.1 min read
- How to turn photos into a single PDF (receipts, IDs, homework)Convert phone photos and scans into one clean PDF with the right page size, orientation and file size — without installing an app.1 min read
- How to verify a downloaded file with a checksum (SHA-256, MD5)Make sure an installer or ISO image hasn't been corrupted or tampered with by comparing its SHA-256 checksum with the one the publisher provides.1 min read
- Image sizes for social media and how to resize for themRecommended pixel sizes and aspect ratios for Instagram, Facebook, LinkedIn, X and YouTube, and how to crop and resize images to fit without distortion.1 min read
- JPG vs PNG vs WebP: which image format should you use?A practical comparison of JPG, PNG, WebP, GIF and SVG — compression, transparency, compatibility — and which to choose for photos, logos and screenshots.1 min read
- VAT explained: how to add or remove VAT from a priceNet vs gross prices, the correct formulas to add and remove VAT, why subtracting the rate gives the wrong answer, and how margins interact with VAT.2 min read
- Your file is too big for the upload form — here's what to doA short decision guide for PDFs, photos and scans that a form refuses: what actually makes a file heavy, what to try first, and what to avoid.2 min read