Liquid Column Millimetres to Atmospheres
Convert with explicit units, definitions and assumptions.
Formula
- Use the units shown beside each field.
- Results update automatically whenever you change an input.
- Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations use standard floating-point arithmetic; exact integer and fraction tools identify their own precision rules.
- Length alone cannot determine pressure. Use liquid density at the actual temperature; mercury is not assumed.
Example Calculation
- Column height: 100 mm
- Liquid density: 1000 kg/m³
- Gravity: 9.80665 m/s²
100 mm of liquid at 1,000 kg/m³ and standard gravity gives about 0.00967841 atm.
Frequently asked questions
How do I use this calculator?
Enter column height, liquid density, gravity. The result updates automatically. Use Reset to restore the example values.
What method does it use?
pressure = density × gravity × height/1000; atm = Pa/101325. Length alone cannot determine pressure. Use liquid density at the actual temperature; mercury is not assumed.
Why might a rounded result differ?
The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.
Are my inputs saved online?
No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.
Check the assumptions and units before using this result. Read about calculation methods.