Pro Calculators and Guides
How to Convert a PDF to PDF/A for Long-Term Archiving
Understand what PDF/A is, why offices and courts ask for it, and how to convert a PDF so fonts and colours are stored inside the file.
Category
Pro Calculators and Guides
Specialist calculators are only useful when you understand the rules behind the numbers. These guides explain what each professional calculator does, which inputs matter, how to read the result and where the official rules come from, covering payroll and tax, immigration and visas, housing, business compliance, engineering and science. Every guide links to a free tool that runs in your browser and keeps your figures private.
318 guides
Pro Calculators and Guides
How to Convert an Hourly Wage to an Annual Salary (and Back)
Find what an hourly rate means over a year, or turn a salary into an hourly figure, with hours per week and weeks worked.
Pro Calculators and Guides
How to Convert an HTML File to PDF (Invoices, Reports and Pages)
Turn an HTML file you made into a PDF. Includes tips for self-contained pages, images and fonts.
Pro Calculators and Guides
How to Convert an Image to Base64 (and Back) for HTML, CSS and Email
Turn a picture into Base64 text for a data URI, or decode Base64 back to an image. When it helps, when it hurts, and how to do it safely.
Pro Calculators and Guides
How to Convert an ODT File to PDF in Your Browser
Turn a LibreOffice or OpenOffice ODT document into a PDF with its headings, paragraphs, lists and tables. Free, private, no upload.
Pro Calculators and Guides
How to Convert an RTF File to PDF in Your Browser
Turn a Rich Text Format document from WordPad or an old word processor into a clean PDF with its text, paragraphs and special characters.
Pro Calculators and Guides
How to Convert an RTF File to Word (DOCX) and Edit It
Convert a Rich Text Format document to a DOCX you can edit in Word, Google Docs or LibreOffice, keeping headings, paragraphs, lists and simple tables.
Pro Calculators and Guides
How to Convert Fuel Economy: km/l, L/100km, mpg (US) and mpg (UK)
Understand fuel economy units and convert between km per litre, litres per 100 km and US and UK miles per gallon.
Pro Calculators and Guides
How to Convert CSV to Excel Without Breaking Bangla or Leading Zeros
Open CSV data in Excel correctly: keep Bangla text, keep the 0 at the start of phone numbers, and get a tidy XLSX file.