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.5 min read
- Celsius to Fahrenheit Formula (and Fahrenheit to Celsius)The exact formulas to convert Celsius to Fahrenheit and back, worked examples, reference tables for weather, fever and ovens, and how far the mental shortcut drifts.6 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.6 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.5 min read
- How to add a watermark to a PDF or a photoStamp CONFIDENTIAL, DRAFT or a recipient's name on a PDF or on photos, pick a size, angle and opacity that work, and see how much protection a watermark gives.6 min read
- How to add page numbers to a PDFPaginate a PDF in your browser: choose the format and position, skip the cover page, start at any number, and avoid the mistakes that come with combining files.6 min read
- How to blur a face, a number plate or a whole imageBlur or pixelate part of a photo before you share it, why a black box in a viewer is not enough, and how strong the effect has to be to actually hide text.6 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, and handle leap years, inclusive counts and working days without an error.6 min read
- How to Calculate Compound Interest (Formula + Examples)The compound interest formula A = P(1 + r/n)^(nt), how compounding frequency changes the answer, APR against APY, regular contributions, and inflation.6 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.5 min read
- How to change uppercase to lowercase (and back)Change case in Word, Google Docs, Excel or a browser, understand why title case is a judgement call, and avoid the Turkish i and German ss traps.7 min read
- How to check and remove GPS location from photos before sharingPhotos often contain the exact place they were taken. See what your files reveal, strip it reliably, and know which sharing routes keep the data and which do not.5 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.6 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.6 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.6 min read
- How to Convert Hourly Pay to Annual SalaryTurn an hourly wage into a yearly, monthly or weekly figure and back, using your real hours and real paid weeks, with overtime and part-time cases.6 min read
- How to convert WebP to JPG (or PNG)Why images saved from websites end up as .webp, what a JPG does to transparency and quality, and how to convert one in your browser or your usual software.6 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.6 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.6 min read
- How to delete pages from a PDFRemove pages from a PDF without re-saving the whole document, what happens to bookmarks, links and printed page numbers, and when to redact instead.7 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.6 min read
- How to fill out a PDF form without printing itFill in a PDF form on your computer or phone, see why answers sometimes vanish in another viewer, flatten before sending, sign it, and handle a PDF with no fields.6 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.5 min read
- How to make a favicon for your websiteThe favicon sizes that still matter, the exact HTML to paste, how SVG favicons work, why the browser keeps showing the old icon, and how to check the result.6 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.6 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.6 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.5 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.6 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.6 min read
- How to prepare a photo for an online application formExam portals, visa sites and job platforms ask for a photo in a precise format. Here is the order to do things in so it is accepted the first time.6 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.6 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, tell the two kinds of PDF password apart, and re-protect the file.6 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.6 min read
- How to remove the background from an imageWhat an automatic cut-out can and cannot separate, why hair and glass are hard, PNG versus WebP output, and how to fix the edges when the result is not clean enough.7 min read
- How to reorder the pages of a PDFMove, duplicate and remove PDF pages on thumbnails, fix a double-sided scan where every other page is upside down or out of order, and keep page numbers right.5 min read
- How to rotate a PDF and save it permanentlyRotate one page or a whole PDF and save the change for good, see why a page looks straight in one viewer and sideways in another, and fix sideways scans.6 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.6 min read
- How to sort a list alphabeticallyPut a list in alphabetical order online, why 10 sorts before 2 in most tools, how accented letters and case are handled, and how to sort in Excel or Word instead.6 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.6 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.6 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.5 min read
- Image sizes for social media and how to resize for themAspect ratios and pixel sizes for Instagram, Facebook, LinkedIn, X, YouTube and TikTok, and the order to crop, resize and compress in so nothing gets cut off.6 min read
- JPG vs PNG vs WebP: which image format should you use?A practical comparison of JPG, PNG, WebP, AVIF, GIF, SVG and HEIC — compression, transparency, compatibility — and which to pick for photos, logos and screenshots.6 min read
- Passport and ID photo sizes by country, from official sourcesPhoto sizes for passports and ID cards in France, Germany, the UK, the US, Canada, Italy, Spain and more, with head size, background colour and digital file limits.8 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.5 min read
- Your file is too big for the upload form — here's what to doA decision guide for PDFs, photos and scans a form refuses: what actually makes each file heavy, what to try first, and the shortcuts that do not work.6 min read