Tools, converters & reference tables for chemists
A curated set of practical utilities instant unit conversion, mesh-to-micron lookup, ppm/ppb relationships, common metric factors and a complete atomic weights index.
Universal Unit Converter
Convert between SI and imperial units across length, mass, volume, pressure, energy and temperature. Results update live as you type.
Need a different conversion? Browse the reference tables below.
Conversion Tables & Atomic Data
Field-tested references compiled by our chemists for everyday lab use.
Particle size mesh to micron conversion
A " + " before a mesh size means particles are retained (larger than the sieve opening). A " − " means particles pass through (smaller than the opening). Example: −325 mesh means particles pass through and are smaller than 44 microns.
| Mesh | Microns | Millimeters | Inches |
|---|---|---|---|
| 4 | 4750 | 4.75 | 0.187 |
| 6 | 3350 | 3.35 | 0.132 |
| 8 | 2360 | 2.36 | 0.0937 |
| 12 | 1700 | 1.7 | 0.0661 |
| 16 | 1180 | 1.18 | 0.0469 |
| 20 | 850 | 0.85 | 0.0331 |
| 30 | 600 | 0.6 | 0.0234 |
| 40 | 425 | 0.425 | 0.0165 |
| 50 | 300 | 0.3 | 0.0117 |
| 60 | 250 | 0.25 | 0.0098 |
| 70 | 212 | 0.212 | 0.0083 |
| 80 | 180 | 0.18 | 0.007 |
| 100 | 150 | 0.15 | 0.0059 |
| 120 | 125 | 0.125 | 0.0049 |
| 140 | 106 | 0.106 | 0.0041 |
| 200 | 75 | 0.075 | 0.0029 |
| 230 | 63 | 0.063 | 0.0025 |
| 270 | 53 | 0.053 | 0.0021 |
| 325 | 45 | 0.045 | 0.0017 |
| 400 | 38 | 0.038 | 0.0015 |
Most common conversion factors
Quick equivalences between parts per million, parts per billion and percentage.
Length
| From | To | Multiply by |
|---|---|---|
| Inch | Centimeter | 2.54 |
| Foot | Centimeter | 30.48 |
| Yard | Meter | 0.9144 |
| Mile | Kilometer | 1.6093 |
Area
| From | To | Multiply by |
|---|---|---|
| Square inch | Square cm | 6.4516 |
| Square foot | Square meter | 0.092903 |
| Square yard | Square meter | 0.83613 |
Volume
| From | To | Multiply by |
|---|---|---|
| Cubic inch | Cubic centimeter | 16.387 |
| Cubic foot | Liter | 28.317 |
Mass
| From | To | Multiply by |
|---|---|---|
| Grain | Milligram | 64.799 |
| Dram | Gram | 1.7718 |
| Ounce | Kilogram | 0.028349 |
| Pound | Kilogram | 0.45359 |
Pressure
| From | To | Multiply by |
|---|---|---|
| Inch of H2O | Pascal | 249.09 |
| Inch of Mercury | Pascal | 3386.4 |
Energy & Power
| From | To | Multiply by |
|---|---|---|
| BTU | Joule | 1055.1 |
| Horsepower | Joule/second | 745.7 |
Atomic weights
Based on atomic mass C = 12.