Pressure Converter
| Unit | Symbol | Equivalent to 1 atm |
|---|
Pascal (Pa): SI unit of pressure, equal to one newton per square meter.
Atmosphere (atm): Standard atmospheric pressure at sea level (101,325 Pa).
Bar: Metric unit, approximately equal to atmospheric pressure (1 bar = 100,000 Pa).
PSI: Pounds per square inch, common in the US for tire pressures and scuba tanks.
mmHg/Torr: Based on mercury column height, used in medicine and meteorology.
| Date & Time | Input | Output | Actions |
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The Complete Guide to Pressure Conversion
Master pressure units with our easy-to-use calculator. Learn formulas, see real-world examples, and get answers to all your questions.
Pressure is all around us—in our car tires, the weather forecast, scuba tanks, and even our blood pressure readings. But with so many different units to measure pressure, it can get confusing. That's where our Pressure Converter comes in!
This guide will walk you through everything you need to know about pressure conversion, from basic formulas to real-world applications. Plus, we'll answer 15 common questions to clear up any confusion.
Try Our Pressure Converter
Convert between 11 different pressure units instantly. Just enter a value, select your units, and see the conversion happen in real-time!
What Exactly is Pressure?
At its simplest, pressure is force divided by area. Imagine standing on one foot versus both feet—the force (your weight) is the same, but the pressure is higher when standing on one foot because the area is smaller.
The Pressure Formula
Pressure = Force ÷ Area
Or in equation form: P = F/A
Where:
- P = Pressure
- F = Force (measured in Newtons)
- A = Area (measured in square meters)
Meet the Pressure Units (Explained Simply)
Here are the 11 pressure units our calculator handles, explained in plain English:
Pascal (Pa)
The Official Unit: This is the SI unit (International System of Units).
Simple Definition: The pressure when 1 Newton of force pushes on 1 square meter of area.
Example:
A single sheet of paper resting on a desk exerts about 1 Pascal of pressure.
Atmosphere (atm)
The Earth's Air Pressure: Based on average atmospheric pressure at sea level.
Simple Definition: The pressure of Earth's atmosphere at sea level.
Example:
Standard atmospheric pressure at sea level is exactly 1 atm.
PSI (psi)
The Everyday Unit: Most common in the US for practical measurements.
Simple Definition: Pounds per square inch.
Example:
Car tires are usually inflated to 30-35 psi. Bicycle tires need 65-100 psi.
Bar
The Metric Alternative: Common in Europe and meteorology.
Simple Definition: Almost equal to atmospheric pressure (1 bar = 100,000 Pa).
Example:
Weather forecasts often use millibars (mbar). Normal sea level pressure is 1013 mbar.
mmHg (mm of Mercury)
The Medical Unit: Used for blood pressure measurements.
Simple Definition: The height of a mercury column the pressure can support.
Example:
Normal blood pressure is around 120/80 mmHg.
Torr
The Science Unit: Named after Evangelista Torricelli.
Simple Definition: Almost identical to mmHg (1 torr = 1 mmHg).
Example:
Used in vacuum science and engineering.
inHg (Inches of Mercury)
The Weather Unit: Used in US weather reports.
Simple Definition: Similar to mmHg but using inches instead of millimeters.
Example:
Standard atmospheric pressure is about 29.92 inHg.
inH₂O (Inches of Water)
The Low-Pressure Unit: For measuring small pressure differences.
Simple Definition: Pressure measured by water column height.
Example:
Used for HVAC systems and draft pressure in chimneys.
The Conversion Formula (How It Works)
The Conversion Process
Our calculator uses a simple two-step process:
- Convert to Pascals: Multiply your value by the conversion factor for your starting unit
- Convert to Target Unit: Divide the Pascal value by the conversion factor for your target unit
Formula: Target Value = (Input Value × Input Unit Factor) ÷ Target Unit Factor
Real-World Example: Car Tire Pressure
Let's say your car manual says tires should be at 2.1 bar, but your gauge reads in PSI:
- 2.1 bar × 100,000 = 210,000 Pascals
- 210,000 Pascals ÷ 6894.76 (PSI factor) = 30.46 PSI
- Result: 2.1 bar = 30.46 PSI
So if your gauge shows around 30-31 PSI, your tires are properly inflated!
Where You'll Use Different Pressure Units
Everyday Life
- PSI: Car and bicycle tires, air compressors
- Bar: European car tires, scuba tanks
- mmHg: Blood pressure monitors
- inHg: Weather reports in the US
Science and Engineering
- Pascal: Physics and engineering calculations
- Torr: Vacuum systems and chemistry
- MPa: Hydraulic systems, material strength
- inH₂O: HVAC systems, fluid dynamics
15 Frequently Asked Questions About Pressure Conversion
1. Why are there so many different pressure units?
Different industries and countries developed their own units over time. For example, mmHg came from early barometers using mercury columns, while PSI developed from the imperial measurement system in the US.
2. What's the difference between PSI and bar?
PSI is an imperial unit (pounds per square inch), while bar is a metric unit. 1 bar equals approximately 14.5 PSI. Bar is more common in Europe, while PSI is standard in the US.
3. Are mmHg and torr exactly the same?
For most practical purposes, yes—1 mmHg = 1 torr. The tiny difference (about 0.000015%) is usually ignored in everyday calculations.
4. What pressure unit should I use for science projects?
Use Pascals (Pa) for scientific calculations since it's the SI unit. For larger values, kilopascals (kPa) or megapascals (MPa) are more convenient.
5. How do I convert blood pressure from mmHg to PSI?
Normal blood pressure of 120/80 mmHg equals about 2.32/1.55 PSI. Use our calculator for precise conversions!
6. What's "standard atmospheric pressure"?
This is the average pressure at sea level: 101,325 Pa, 1 atm, 1013.25 mbar, 760 mmHg, or 14.696 PSI.
7. Why do scuba divers use different pressure units?
Scuba tanks are typically measured in bar (metric) or PSI (imperial). A full tank is about 200-300 bar or 3000-4500 PSI.
8. How accurate is the pressure converter?
Our calculator uses precise conversion factors with up to 6 decimal places, making it accurate for all practical applications.
9. Can I convert negative pressure or vacuum?
Yes! Enter negative values to convert vacuum pressures. For example, -1 atm is a perfect vacuum.
10. What's the smallest pressure unit available?
Pascal (Pa) is the base unit, but for very small pressures, you might see millipascals (mPa) or micropascals (μPa) in scientific contexts.
11. Why is atmospheric pressure 1 atm at sea level?
This was defined as the average pressure exerted by the atmosphere at sea level, providing a convenient reference point.
12. How does altitude affect pressure conversions?
Atmospheric pressure decreases with altitude. Our calculator converts between units but doesn't account for altitude changes—it assumes sea level conditions for atm.
13. What's the most common pressure unit worldwide?
Pascal is the official SI unit, but bar and PSI are most common in practical applications depending on the region and industry.
14. Can I save my conversion results?
Yes! Use our export features to save results as PDF, HTML, or text files for future reference or sharing.
15. How do I know which unit to use for my project?
Check what units your equipment uses or what's standard in your country/industry. When in doubt, use Pascals for scientific work or consult relevant standards.
Quick Reference Conversion Table
Common Pressure Equivalents
1 atmosphere (atm) equals:
- 101,325 Pascals (Pa)
- 101.325 kilopascals (kPa)
- 1.01325 bar
- 760 mmHg
- 760 torr
- 14.6959 PSI
- 29.9213 inHg
- 406.782 inH₂O
Tips for Using Our Pressure Converter
Pro Tips
- Use the swap button to quickly reverse your conversion
- Export your results when you need to save calculations for school or work
- Check the unit reference table to understand all 11 pressure units
- Try different values to see how the same pressure reads in different units
- Bookmark the calculator for quick access when you need it
Whether you're a student studying physics, a mechanic checking tire pressure, a nurse reading blood pressure, or just curious about how pressure works, our Pressure Converter makes it simple to work with any pressure unit. The key is understanding that all these units are just different ways of measuring the same thing—how much force is being applied over an area.
Remember: Pressure = Force ÷ Area. Everything else is just different units for expressing that relationship!