Guides
In-depth explainers behind ToolHare’s calculators and converters — the background, rules and worked examples that sit beneath the numbers.
How VAT Works in the UK
UK VAT explained: the 20% standard rate, reduced and zero rates, registration thresholds and worked examples of adding and removing VAT.
Percentage Change vs Percentage Points
The difference between a percentage change and a percentage point change, with worked examples from interest rates and opinion polls.
Why Britain Still Weighs in Stone
Why the UK still weighs body weight in stone and pounds, from the 1835 Weights and Measures Act to today's NHS records.
Miles, Kilometres and Britain's Half-Metric Muddle
Why UK road signs stayed in miles after Britain's 1965 metrication push, and how to convert kilometres to miles accurately.
UK Bank Holidays and Working-Day Counting
How England, Scotland and Northern Ireland's bank holidays differ, and how working-day counting handles weekends and substitute days.
How Password Strength Actually Works
How password entropy is calculated, why length beats complexity rules, and what NCSC and NIST guidance actually recommends.
What Base64 Is and When (Not) to Use It
What Base64 encoding actually does, why it adds about 33% overhead, and when it's the right tool versus encryption.
Hashing Explained: MD5, SHA-256 and Why They Differ
How cryptographic hashing works, why MD5 and SHA-1 are broken for security, and why SHA-256 is the modern default.
A Practical Guide to JSON for Non-Developers
A plain-English guide to JSON's six value types, reading nested structure, and the syntax rules that cause invalid-JSON errors.
How Anagram and Word-Unscrambler Solvers Work
How word unscramblers and anagram solvers find matches instantly using a sorted-letters dictionary index instead of brute-force permutations.
Wordle Strategy: Starting Words and Elimination Logic
Wordle strategy explained: how tile colours work, the duplicate-letter scoring rule, and why elimination beats guessing likely answers.
How Random Number Generation Works in a Browser
How browser random number generation works, the difference between Math.random and crypto.getRandomValues, and how modulo bias is avoided.