Engineering Unit Converter — Pressure, Power & Torque
One workspace for the three quantities mechanics, engineers and car enthusiasts convert most: pressure (psi, bar, kPa), power (hp, kW, PS) and torque (N·m, lb-ft). Pick a tab below — each has its own linkable page, benchmarks and formulas.
Real-World Benchmarks
Multi-Unit Conversion Matrix
| Group | Measurement | Symbol | Equivalent Value |
|---|---|---|---|
| SI & Metric | Pascal | Pa | 220,632.2334 |
| SI & Metric | Hectopascal | hPa | 2,206.3223 |
| SI & Metric | Kilopascal | kPa | 220.6322 |
| SI & Metric | Megapascal | MPa | 0.2206 |
| SI & Metric | Bar | bar | 2.2063 |
| SI & Metric | Millibar | mbar | 2,206.3223 |
| SI & Metric | Kilogram-force per cm² | kgf/cm² | 2.2498 |
| Imperial & US Customary | Pound per Square Inch | psi | 32 |
| Imperial & US Customary | Kilopound per Square Inch | ksi | 0.032 |
| Atmospheric & Manometric | Standard Atmosphere | atm | 2.1775 |
| Atmospheric & Manometric | Torr | Torr | 1,654.8778 |
| Atmospheric & Manometric | Millimeter of Mercury | mmHg | 1,654.8776 |
| Atmospheric & Manometric | Inch of Mercury | inHg | 65.1527 |
| Atmospheric & Manometric | Inch of Water | inH₂O | 885.757 |
Step-by-Step Mathematical Explanation
- Step 1: Convert 32 psi to the base unit (Pa): 32 × 6,894.75729317 = 220,632.233381 Pa.
- Step 2: Convert base pascals to bars: 220,632.233381 ÷ 100,000 = 2.206322 bar.
- Direct factor: 1 psi = 0.06894757 bar.
Essential Conversion Factors
Pound per Square Inch: US tire, air compressor and hydraulic pressure
Quick Answer & Key Engineering Factors
Direct Answer: Pressure: 1 bar = 14.5038 psi and 1 psi = 0.0689 bar (6.895 kPa). Power: 1 hp = 0.7457 kW and 1 kW = 1.341 hp; one metric horsepower (PS) is 0.7355 kW. Torque: 1 N·m = 0.7376 lb·ft and 1 lb·ft = 1.3558 N·m. All factors derive from the exact pound-force (4.4482216 N) and the SI pascal, watt and newton-meter.
Understanding Engineering Units & Conversion Math
Pressure, power and torque all build on the SI newton. Pressure is force per area (N/m² = Pa), torque is force times lever arm (N·m), and power is work per second (N·m/s = W). Imperial units swap in the pound-force, inch and foot — which is why every imperial factor traces back to 4.4482216152605 N and 0.3048 m.
1. Pressure: PSI to Bar (psi → bar)
One psi is one pound-force on a square inch: 4.4482216 N ÷ 0.00064516 m² = 6,894.76 Pa. A bar is 100,000 Pa, so:
Example: 35 psi × 0.0689476 = 2.41 bar.
2. Torque: Newton-Meters to Pound-Feet (N·m → lb·ft)
One pound-foot is one pound-force acting on a one-foot lever: 4.4482216 N × 0.3048 m = 1.35582 N·m. Divide by that factor:
Example: 400 N·m × 0.737562 = 295.0 lb·ft.
Power Shortcut: kW ≈ ¾ of Horsepower
Mechanical horsepower is 745.7 W, so kilowatts are roughly three-quarters of horsepower. The shortcut is within 0.6% of the exact value:
300 hp × 0.75 = 225 kW (exact value: 223.7 kW).
Key Engineering Conversion Constants
| Unit | SI Value | Common Equivalent | Definition |
|---|---|---|---|
| 1 psi | 6,894.757 Pa | 0.068948 bar | 1 lbf per square inch |
| 1 bar | 100,000 Pa | 14.5038 psi | Exactly 10⁵ Pa |
| 1 atm | 101,325 Pa | 14.6959 psi | Standard sea-level pressure |
| 1 hp | 745.700 W | 1.01387 PS | 550 ft·lbf per second |
| 1 PS | 735.499 W | 0.98632 hp | 75 kgf·m per second |
| 1 lbf·ft | 1.355818 N·m | 12 lbf·in | 1 lbf on a 1 ft lever |
| 1 kgf·m | 9.80665 N·m | 7.2330 lbf·ft | 1 kgf on a 1 m lever |
Frequently Asked Questions
What is the difference between torque and power?
Torque is rotational force (how hard an engine twists); power is how fast that work is done. They are linked by engine speed: P (kW) = τ (N·m) × rpm ÷ 9,549, or hp = lb·ft × rpm ÷ 5,252.
Why do car specs list PS, hp and kW?
European makers quote metric horsepower (PS, CV), US and UK makers quote mechanical horsepower (hp), and official EU registration documents use kilowatts. 100 PS = 98.6 hp = 73.5 kW.
Is a bar the same as an atmosphere?
Almost. One standard atmosphere is 1.01325 bar (101,325 Pa), so the two differ by about 1.3%. For tire and diving pressures they are often used interchangeably.
Which pressure units do tire gauges use?
US gauges read psi, European ones bar, and Canadian, Australian and many Asian gauges kPa. A typical car tire at 32 psi equals 2.2 bar or 220 kPa.