Guides

F Free Online Tools for Designers Colour conversion, contrast checks, gradients, shadows and image resizing are the small jobs designers… F Free Online Tools for Developers JSON, XML, Base64, URL encoding and HTML entities come up in almost every project.… F Free Online Tools for SEO and Marketing Snippet previews, robots.txt, Open Graph tags, FAQ markup, slugs and ad-copy limits are the… F Free Online Tools for Small Business Pricing, discounts, tips, wages, timesheets and team draws are the everyday arithmetic of running… F Free Online Tools for Students Word limits, grade targets, GPA and percentages come up all term. These free, private… F Free Online Tools for Writers and Editors Counting, cleaning and comparing text are the daily jobs of writers and editors. These… H How to Add a Text Watermark to a PDF Stamp text such as DRAFT or CONFIDENTIAL diagonally across every page of a PDF.… H How to Add or Subtract Days, Months or Years from a Date Add or subtract days, months or years from a date. Days are exact; months… H How to Add Page Numbers to a PDF Add page numbers to a PDF at the bottom left, centre or right, starting… H How to Add, Subtract, Multiply and Divide Fractions Adding and subtracting fractions needs a common denominator; multiplying and dividing does not. Here… H How to Build a Reusable Prompt Template A prompt template has {{placeholders}} that you fill from a list of values, so… H How to Calculate a Discount and Sale Price A sale tag says 35% off; you want to know what you will pay.… H How to Calculate a Subnet from an IP and CIDR Prefix A CIDR prefix such as /24 tells you how many addresses a network holds… H How to Calculate a Tip and Split the Bill Tipping maths is easy once you settle two questions: what the percentage applies to,… H How to Calculate BMI and What It Means BMI is a single number worked out from your height and weight. Here is… H How to Calculate BMR and Daily Calorie Needs (TDEE) Your calculator result is only as good as the inputs you give it. This… H How to Calculate Exact Age in Years, Months and Days Exact age in years, months and days depends on a borrowing rule when the… H How to Calculate File Download Time Download time is file size divided by connection speed, but size is counted in… H How to Calculate Mean, Median, Mode and Range Mean, median and mode are three ways to describe the middle of a list… H How to Calculate Percentages: Of, What Percent and Change Percentages come in three flavours: a percent of a number, what percent one number… H How to Calculate Running Pace per Kilometer and Mile Pace is just time divided by distance, but runners quote it per kilometre in… H How to Calculate Standard Deviation and Variance Standard deviation tells you how far numbers typically sit from their average. This guide… H How to Calculate the Final Exam Score You Need To find what you need on a final, work backwards from your target grade… H How to Calculate the Number of Days Between Two Dates Count the days between two dates, and see the same gap in weeks. A… H How to Calculate Timesheet Hours and Overtime Adding up shifts by hand invites small errors, especially with half hours and overnight… H How to Calculate Your GPA on the 4.0 Scale GPA is the average of your grade points weighted by credit hours. This guide… H How to Change Text Case: Upper, Lower, Sentence and Title Upper, lower, sentence, title, capitalised, alternating and inverse: seven case options and what each… H How to Check Ad Copy Against Google and Meta Character Limits Ad platforms cut or reject text that is too long. Check headlines and descriptions… H How to Check Color Contrast for WCAG Accessibility WCAG sets minimum contrast ratios so text is readable for people with low vision.… H How to Compare Two Texts and See the Differences Paste an original and a revised version and the diff shows what was added,… H How to Compress an Image to Reduce File Size Compression shrinks a photo by re-saving it at lower quality. It works on JPEG… H How to Convert a Time Between Time Zones Convert a date and time between 14 common zones, with daylight saving handled for… H How to Convert an Image to a Base64 Data URL Turn an image into a Base64 data URL you can paste directly into HTML… H How to Convert an IPv4 Address to Binary, Hex and Decimal An IPv4 address is a 32-bit number written as four decimal bytes. See 192.168.1.1… H How to Convert Area: Square Feet, Square Meters and Acres Square feet, square metres, acres and hectares are all in everyday use, and the… H How to Convert Between Fractions and Decimals A fraction is a division in disguise, so converting it to a decimal is… H How to Convert Between Kilograms, Pounds and Ounces Pounds, ounces, kilograms and grams convert exactly because the pound is defined from the… H How to Convert Between Metric and Imperial Length Units Metric and imperial length units are linked by exact definitions: an inch is 2.54… H How to Convert Bytes, KB, MB, GB and TB A gigabyte can mean 1,000 megabytes or 1,024, depending on who is counting. This… H How to Convert Celsius, Fahrenheit and Kelvin Celsius, Fahrenheit and Kelvin are linked by simple formulas. Examples cover the boiling point… H How to Convert Height Between Feet and Inches and Centimeters Heights are written as feet and inches in some countries and centimetres in most… H How to Convert HEX Colors to RGB and HSL A HEX colour, an RGB triple and an HSL value can all describe the… H How to Convert Hourly Pay to Annual Salary Comparing a job paid by the hour with one paid a yearly salary comes… H How to Convert Images Between PNG, JPG and WebP Convert between PNG, JPEG and WebP right in your browser. Transparent PNGs get a… H How to Convert Images to a PDF Combine PNG or JPG images into a single PDF, one image per page. Handy… H How to Convert JSON to CSV and Back Convert a flat array of JSON objects to CSV for a spreadsheet, or CSV… H How to Convert Numbers to Scientific Notation Scientific notation writes very large or very small numbers as a number between 1… H How to Convert Speed: km/h, mph, m/s and Knots Speed limits in km/h or mph, wind in knots, sprinters in metres per second:… H How to Convert Test Points to a Percentage and Letter Grade Turning 43 out of 50 into a percentage and a letter is simple division,… H How to Convert Volume: Liters, Cups, Tablespoons and Gallons Cups, tablespoons, teaspoons and gallons differ between countries. The converter uses US customary measures,… H How to Count Characters With and Without Spaces Character limits decide how long a post, a text message or a meta description… H How to Count Words in Any Text A word count sounds simple until two programs give you different numbers for the… H How to Create a Clean URL Slug from a Title A URL slug is the readable end of a web address. Good ones are… H How to Create a CSS Box Shadow A CSS box shadow takes an offset, a blur, a spread and a colour.… H How to Create a CSS Linear Gradient A CSS linear gradient blends two colours along an angle, with no image file… H How to Create a Favicon (.ico) from an Image Turn any logo into a multi-size favicon.ico containing 16, 32, 48 and 64 pixel… H How to Create a robots.txt File A robots.txt file tells crawlers which parts of your site not to visit. It… H How to Create FAQ Schema (FAQPage JSON-LD) FAQ schema marks up questions and answers in JSON-LD so search engines can read… H How to Create Open Graph and Twitter Card Meta Tags Open Graph and Twitter Card tags control the title, description and image shown when… H How to Crop an Image to an Exact Size Cropping with exact pixel values gives a precise rectangle: the left and top offsets… H How to Delete or Reorder PDF Pages List the pages you want to keep, in the order you want them, and… H How to Encode and Decode Base32 and Base58 Base32 and Base58 are text encodings designed to be easy to read and copy.… H How to Encode and Decode Base64 Base64 turns any bytes into plain text characters so they survive email, URLs and… H How to Encode and Decode HTML Entities HTML entities let you show characters such as the less-than sign and the ampersand… H How to Escape and Unescape a JSON String To put text inside a JSON string, quotes, backslashes and line breaks must be… H How to Estimate Ideal Body Weight "Ideal weight" formulas are decades old and disagree with each other by several kilograms.… H How to Estimate the Cost of an LLM API Call An LLM call costs the input tokens times one price plus the output tokens… H How to Estimate the Token Count of a Prompt Language models read text in tokens, not words. The counter estimates tokens from characters… H How to Find and Replace Text Online Find and replace is simple until "cat" also changes "concatenate". This guide shows the… H How to Find the GCF and LCM of Two Numbers The greatest common factor shrinks fractions and splits things into equal groups; the least… H How to Find Your Public IP Address Your public IP address is the address websites see when you connect. The tool… H How to Format and Validate XML Check whether XML is well-formed and re-indent it for reading. The formatter catches mismatched… H How to Format, Beautify or Minify JSON Minified JSON is hard to read and pretty-printed JSON is hard to ship. The… H How to Generate a Strong Password A strong password is long and unpredictable, and it is used on exactly one… H How to Generate Random Numbers in a Range Random numbers are easy to ask for and surprisingly easy to get wrong. This… H How to Merge PDF Files Into One Combine several PDFs into one document in your browser, without uploading them. Check the… H How to Pick Random Winners or Split a List into Teams Pick winners from a list of names, or split everyone into balanced teams. Enter… H How to Preview Your Title and Meta Description in Google Google cuts titles by pixel width and descriptions by length, so a title that… H How to Remove Duplicate Lines from a List Clean a list by removing repeated lines, and decide whether "Red" and "red" count… H How to Remove Extra Spaces from Text Double spaces, trailing spaces and invisible characters sneak in when you copy from PDFs,… H How to Remove Line Breaks from Text Text copied from a PDF or email often has a hard return at the… H How to Resize an Image Without Uploading It Resize an image to a set width without uploading it. Keep the aspect ratio… H How to Rotate or Flip an Image Rotate an image by 90, 180 or 270 degrees, or flip it horizontally or… H How to Rotate PDF Pages Rotate every page of a PDF by 90, 180 or 270 degrees to fix… H How to Simplify Ratios and Solve Proportions A ratio compares two quantities, and a proportion says two ratios are equal. This… H How to Solve a Quadratic Equation A quadratic equation has the form ax² + bx + c = 0. The… H How to Sort Lines Alphabetically or by Length Sort a list A to Z, Z to A, by length, naturally (file2 before… H How to Split a PDF and Extract Pages Extract the pages you need from a PDF using a simple range such as… H How to URL Encode and Decode Text URLs can only contain certain characters, so spaces, accents and symbols are written as… H How to Use a Caesar Cipher and ROT13 The Caesar cipher shifts every letter along the alphabet by a fixed number of… H How to Validate JSON and Find Errors JSON is strict: one stray comma, single quote or missing bracket makes the whole… H How to View and Edit PDF Metadata PDF metadata, such as title, author, subject and keywords, travels with the file and… H How to View and Remove EXIF Data from a Photo Photos can carry a hidden label: the camera model, the time, and sometimes the… H How to Write a Clean Professional Email Signature A good email signature is short, plain and useful. The generator builds a clean… H How to Write Titles in AP, Chicago, MLA and APA Title Case AP, Chicago, MLA and APA all capitalise titles differently, mainly in how they treat… M Margin vs Markup: How to Calculate Both If you want a 40% margin, adding 40% to your cost will not get…