Everyday reference tables
Unit converters, postal formats, country codes, MIME types, and more lookup tables.
Units
- Area unit conversion Square meters, acres, hectares, square feet, and square miles.
- Clothing size conversion (approx) Rough letter/number size mapping across US, UK, EU, and CN labels.
- Cooking measurement conversion Kitchen spoon, cup, and oven conversions used in recipes worldwide.
- Data storage units (KB MB GB TB) Bits, bytes, and decimal vs binary prefixes used by disks and OS displays.
- Energy and power units Joule, calorie, kWh, BTU, watt, horsepower — home and science conversions.
- Fuel economy conversion (MPG ↔ L/100 km) Convert US MPG and UK MPG to liters per 100 kilometers.
- Length unit conversion Common length conversions: meter, kilometer, mile, foot, inch, yard, nautical mile.
- Paper sizes (ISO A series & Letter) A0–A6 millimeter sizes plus US Letter and Legal.
- Pressure unit conversion Pascal, bar, psi, atm, mmHg — tire and weather pressure units.
- Shoe size conversion (US UK EU JP) Approximate men’s and women’s shoe size cross-reference across regions.
- SI unit prefixes (nano to tera) Metric prefixes from nano to tera with symbols and powers of ten.
- Speed unit conversion km/h, mph, m/s, knots — common speed conversions.
- Temperature conversion (°C °F K) Convert between Celsius, Fahrenheit, and Kelvin with formulas and common checkpoints.
- Volume unit conversion Liters, milliliters, gallons (US/UK), cups, fluid ounces, cubic meters.
- Weight and mass unit conversion Kilogram, gram, pound, ounce, stone, ton — everyday mass conversions.
Places & codes
- Major airport IATA codes Three-letter IATA codes for frequently searched international airports.
- International dialing codes by country ITU country calling codes (dial-out prefixes) for common destinations.
- Country capitals (selected) Capitals of frequently searched countries and regions.
- Currency codes (ISO 4217) Common ISO 4217 currency codes with symbol and typical minor units.
- ISO country codes (alpha-2 / alpha-3) Common ISO 3166-1 alpha-2 and alpha-3 codes used in forms, shipping, and APIs.
- Postal code formats by country Typical postal / ZIP code patterns, length, and examples by country — not a full address database.
- Country power plug types and voltage Common AC plug types (A–N), voltage, and frequency by country or region.
- Common timezone UTC offsets Standard UTC offsets for major cities and zones. Daylight saving can change clocks — double-check before you schedule.
- US state and territory abbreviations Two-letter USPS abbreviations for the 50 states, DC, and common territories.
Web & files
- ASCII printable characters Decimal codes 32–126: space through tilde.
- Common MIME types Content-Type values for web, documents, images, audio, and video.
- CSS size units (px rem em vh) When to use px, rem, em, %, vw/vh, and other CSS length units.
- Common file extensions What popular file extensions usually mean on desktops and the web.
- HTML character entities Frequently needed HTML entities for symbols, punctuation, and whitespace.
- HTTP status codes quick reference Common HTTP response codes with a short meaning for APIs and debugging.
- Number bases (decimal hex binary) 0–32 in decimal, hexadecimal, and binary — handy for debugging and bit flags.