Personal notes
Reference values I look up often enough to keep on one page.
Unit conversions
| From | To | Factor |
|---|
| 1 inch | centimetres | 2.54 |
| 1 foot | metres | 0.3048 |
| 1 mile | kilometres | 1.609344 |
| 1 pound | kilograms | 0.45359237 |
| 1 US gallon | litres | 3.785411784 |
| 1 UK pint | millilitres | 568.26125 |
| Fahrenheit | Celsius | (F − 32) × 5 ⁄ 9 |
Date and time formats
| Format | Example |
|---|
| ISO 8601 date | 2026-09-24 |
| ISO 8601 UTC timestamp | 2026-09-24T08:15:30Z |
| ISO 8601 with offset | 2026-09-24T10:15:30+02:00 |
| RFC 3339 (same, space allowed) | 2026-09-24 08:15:30Z |
| Unix time (seconds) | 1790237730 |
| ISO week date | 2026-W39-4 |
Paper sizes
| Size | Millimetres |
|---|
| A3 | 297 × 420 |
| A4 | 210 × 297 |
| A5 | 148 × 210 |
| US Letter | 216 × 279 |
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