Guides
Clear, practical answers to the most common questions, with step-by-step instructions, worked examples and links to the right tools.
Popular:Merge PDFReduce PDF sizeHEIC to JPGChatGPT table to ExcelOvertime pay
Hours and pay
Working out hours, breaks, decimal time and overtime.
How to calculate hours worked, including lunchSubtract the start time from the end time, take off unpaid breaks, then add the days together. Here is how to do each step without the usual mistakes.Minutes to decimal hours for payrollPayroll needs hours as decimals, so 7 hours 45 minutes becomes 7.75. Divide the minutes by 60, or look them up in the full 0 to 60 chart.How to calculate overtime payUnder US federal law, overtime is owed for hours over 40 in a single workweek at one and a half times the regular rate. Here is how to work it out, with five checked examples.
Making PDFs smaller and combining them without uploading.
How to reduce a PDF's file size for emailMost oversized PDFs are big because of scanned pages or photos. Find the cause first, then use the smallest fix that gets the file under the limit.How to merge PDF files on any device without uploadingYou can combine PDFs on a phone or computer without sending them to anyone's server. One method works the same everywhere, and Macs have two built-in options.
Photos and images
Hitting form size limits, converting iPhone photos and passport photos.
How to get a photo under 20 KB for an online formApplication forms often ask for a photo or signature under 20 KB, sometimes with exact pixel sizes too. Here is how to meet every part of the rule on the first try.How to convert HEIC to JPGiPhones save photos as HEIC, which many websites and older programs can't open. Here is how to convert them on any computer, in batches, and how to stop it happening.How to take a passport photo at homeA phone camera is good enough for a passport photo if you get the light, background and crop right. These are the official US and UK rules and how to meet them at home.
Maths and money
Percentages and loan payments, worked through step by step.
How to calculate percentage increaseTake the difference, divide it by the starting value and multiply by 100. The formula is short. Most mistakes come from the traps around it, which this guide works through.How EMI is calculatedAn EMI is the fixed monthly payment that clears a loan, interest included, by the end of its term. Here is the formula, worked through with real numbers.
AI answers and Markdown
Getting tables, PDFs and diagrams out of ChatGPT, Claude and Gemini, and previewing Markdown.
How to copy a ChatGPT table into Excel or Google SheetsCopy the table you can see, not its Markdown, and it usually pastes into columns. When it lands in one column or the numbers come out wrong, these are the fixes.How to save a ChatGPT, Claude or Gemini answer as a PDFPrinting the chat page gives you sidebars, cut-off tables and broken code. Copy the answer as Markdown, lay it out as a document, then save it as a PDF.How to preview Markdown files online, with tables, Mermaid and mathsOpen the file or paste the text into a previewer that supports GitHub-style Markdown. Use the test file below to see what any previewer can handle.How to render Mermaid diagrams in MarkdownPut the diagram code in a fenced block tagged mermaid. GitHub, GitLab and VS Code draw it; many other places show it as code. Here is how to make it render, and what to do where it can't.How to create a Markdown table without writing pipesType into a grid or paste cells from a spreadsheet and let a generator write the pipes, dashes and escapes. Here is how, plus the rules for when you edit a table by hand.
JSON
Fixing invalid JSON, generating TypeScript types and comparing two documents.
How to fix common JSON syntax errorsMost invalid JSON has one of a handful of mistakes. Find where the parser stopped, look just before it, and fix it by hand or with a repair you then check.How to convert JSON to TypeScript interfacesPaste a real sample and generate the interfaces, then check the few things a generator can't know from the data: optional fields, nulls, empty arrays and dates.How to compare two JSON filesA text diff flags every reordered key as a change. Compare by structure instead, decide whether array order matters, and only real changes are left.