Our guides explain the ideas behind the tools in plain language, with examples you can actually follow. Use them when you want to understand the answer rather than simply get one.
How we approach these guides: they are written to help with the actual task in front of you. We use examples, point out common mistakes and explain where a simple calculator has limits. If you spot an error or something that needs clarification, please let us know through the Contact page.
Percentages, age, pricing and break-even planning.
QR codes, barcodes, Base64 and file transfers.
Invoices, margins, pricing and practical workflows.
A short checklist for deciding whether an online calculation is suitable for a quick estimate or needs to be verified elsewhere.
Read the guide →A simple checklist for making printed QR codes easier to understand and more useful for people who cannot or do not want to scan them.
Read the guide →Simple wording and practical details that can make an invoice easier for a customer to understand and easier for a business to follow up.
Read the guide →A practical explanation of what the break-even number can tell you about costs, pricing and sales targets—and what it cannot tell you.
Read the guide →A practical guide to choosing units that make measurements easy to understand, compare and communicate.
Read the guide →The Fahrenheit-to-Celsius formula explained with familiar examples and a quick way to check the result.
Read the guide →A simple pre-print checklist to reduce the chance of distributing a QR code that is difficult to scan or points to the wrong place.
Read the guide →Why there is no single “good” margin and how to think about margin in the context of costs, industry and pricing.
Read the guide →Examples of when changing text to uppercase, lowercase, title case or sentence case can save editing time.
Read the guide →Simple ways to use random numbers for selections, games, testing and demonstrations, plus an important security warning.
Read the guide →A handy reference for everyday temperatures, with examples that make the two scales easier to compare.
Read the guide →Clear up the difference between bits and bytes so connection speeds and file sizes make more sense.
Read the guide →A practical approach to invoice numbers that keeps records easy to find, reconcile and explain.
Read the guide →Understand the difference between passwords and passphrases and why longer credentials are often easier to secure.
Read the guide →A practical introduction to Code 128, Code 39, EAN-13, EAN-8 and UPC and the kinds of jobs they are commonly used for.
Read the guide →A plain-English explanation of Base64 encoding, common uses, size overhead and why Base64 should not be confused with encryption.
Read the guide →A practical look at word counts, character counts and when each measurement is useful for school, work, forms and online publishing.
Read the guide →See how to calculate sale prices, savings and the original price when a discount percentage is given.
Read the guide →A quick explanation of the kilometres-to-miles conversion factor with examples for travel, distance and running.
Read the guide →Learn why a 100 Mbps connection does not transfer 100 MB every second, and how to estimate upload or download time.
Read the guide →Understand break-even sales, fixed costs, variable costs and target profit with a simple worked example.
Read the guide →Margin and markup are related but not interchangeable. Here is how to calculate each one and why the difference matters in pricing.
Read the guide →The Celsius-to-Fahrenheit formula explained with familiar temperature examples and a quick way to check your answer.
Read the guide →A practical checklist for preparing a clear invoice that a client can understand and a business can file.
Read the guide →Practical password advice covering length, uniqueness, passphrases, password managers and multi-factor authentication.
Read the guide →A practical comparison of traditional one-dimensional barcodes and two-dimensional QR codes, including when to use each.
Read the guide →Understand how calendar age is calculated in years, months and days, including birthdays and leap years.
Read the guide →Learn the percentage change formula with everyday examples involving prices, measurements and business figures.
Read the guide →Simple, realistic ways a small business can use QR codes to connect printed material with useful online information.
Read the guide →A straightforward guide to creating a QR code, checking that it works and using it on posters, menus, documents and other everyday materials.
Read the guide →