If you have ever inflated car tires or used a pump, you have likely encountered different units of pressure: bar, atmospheres (atm), and psi. These units are often confused, but there are important differences between them. In this article, we will figure out what they mean, where they are used, and how to convert them into one another.
Main Units of Pressure Measurement
| Unit | Symbol | Value in Pascals | Where it's used |
|---|---|---|---|
| Bar | bar | 100,000 Pa | Europe, auto service centers |
| Atmosphere | atm | 101,325 Pa | Physics, outdated GOST standards |
| Pounds per square inch | psi | ≈6,894.76 Pa | USA, motorsports, pumps |
How to Convert Pressure?
- 1 atm ≈ 1.013 bar
- 1 bar ≈ 14.5 psi
- 1 atm ≈ 14.7 psi
If your pump shows pressure in psi, but the tire instructions specify bar — it's not a problem. Just below on this page, there is a handy calculator that will instantly convert everything for you.
Where are these units used?
bar - This is the standard unit in Europe and CIS countries. It is used in car pumps, tire service stations, and auto shops.
atm - This is a physical unit of pressure, equal to normal atmospheric pressure. It is now rarely used, mainly in science.
psi - The American system. It is used in the USA, as well as in some models of pumps, compressors, and motorcycles.
Pressure Calculator (Atmospheres, Bar, and PSI)
Below is a convenient calculator for converting pressure from one unit to another:
Pressure Converter
Conclusions
- For tires and pumps, bar and psi are most commonly used.
- The atmosphere is an outdated but still occasionally encountered unit.
- For quick conversion, use the built-in pressure calculator above.
Now you know the differences between bar, atmospheres, and psi, and you can easily navigate these values when inflating tires, working with compressors, and choosing equipment.
📌 How Much Should You Inflate Your Tires?
Tire pressure values depend on the type of vehicle, weight, operating conditions, and the manufacturer's recommendations. The data below are averages that can be used as a guide, but it's always best to check the technical passport or the sticker on the car body (often located on the door pillar or near the fuel filler cap). For bicycles and motorcycles, you should look at the marking on the tire itself.| Vehicle Type | Pressure, bar | Pressure, psi | Notes |
|---|---|---|---|
| Passenger Car | 2.0 – 2.5 bar | 29 – 36 psi | Usually front is lower, rear slightly higher under load |
| Crossover / SUV | 2.2 – 2.7 bar | 32 – 39 psi | Increased pressure due to weight |
| Motorcycle (Road) | 2.2 – 2.5 bar | 32 – 36 psi | Front and rear wheel may differ |
| Scooter / Moped | 1.8 – 2.2 bar | 26 – 32 psi | Pressure should be increased when riding with a passenger |
| Bicycle (Road) | 6 – 9 bar | 87 – 130 psi | Thin tires, high pressure |
| Bicycle (Mountain MTB) | 2.0 – 3.0 bar | 29 – 44 psi | Softer for better traction |
| Electric Scooter / E-bike | 3.0 – 4.5 bar | 44 – 65 psi | Important to monitor pressure — affects range |
⚠️ Important!
- Do not overinflate tires — this worsens traction and causes uneven wear.
- Underinflated tires can lead to overheating and increased fuel/energy consumption.
- Measure pressure only on cold tires (before driving).
Additionally:
1. To monitor tire pressure, you can purchase a Tire Pressure Monitoring System (TPMS). These are sold for trucks as well as for four-wheeled vehicles (cars). For two-wheeled vehicles (motorcycles, scooters, mopeds, bicycles, e-bikes), similar systems also exist. This is a monitor and pressure sensors that attach to the wheel's valve stem.
2. Consider buying a cordless pump (compressor). It takes up little space and often has additional functions (flashlight, power bank). It can be used to inflate tires, balls, boats, inflatable tubes, etc.
