What is this converter?
Converts pressure between pascals, kilopascals, bar, psi, atmospheres, and millimetres of mercury. All conversions pass through the pascal, the SI derived unit of pressure.
Use it when:
- A tyre, gauge, or specification quotes pressure in a unit you do not work in.
- You are converting between psi and bar for equipment ratings.
- A medical or meteorological reading is given in mmHg or atmospheres.
Intended for: Engineers, technicians, drivers, and anyone reading a pressure gauge.
How is this calculated?
- Each supported unit is defined by a fixed conversion factor relative to one base unit for the quantity (for example, the metre for length).
- The value you enter is first converted from the source unit into that base unit by multiplying by the source unit's factor.
- The base value is then converted into the target unit by dividing by the target unit's factor.
- Because both factors are exact constants, the conversion is a single deterministic multiplication and division — the same input always produces the same output.
Example
Converting 32 psi (a typical car tyre pressure) to bar.
- 1 psi ≈ 6,894.757 pascals.
- 1 bar is exactly 100,000 pascals.
- 32 × 6,894.757 ÷ 100,000 ≈ 2.206.
Result: 32 psi ≈ 2.21 bar.
Frequently asked questions
Is this gauge pressure or absolute pressure?
The converter changes units only; it does not change the reference. If your reading is gauge pressure (relative to the surrounding atmosphere) the result is still gauge pressure. Converting between gauge and absolute means adding or subtracting one atmosphere separately.
How do bar and atmosphere differ?
A bar is exactly 100,000 pascals; a standard atmosphere is 101,325 pascals. They are close but not identical — about 1.3% apart.
Assumptions
What this converter takes as given:
- Conversion factors are the internationally standardised definitions of each unit, not regional or historical variants.
- The value you enter is treated as an exact quantity — no measurement uncertainty is carried through the conversion.
- Results are rounded only for display; the underlying arithmetic uses full precision.
Limitations
What this converter cannot know or does not model:
- The converter does not know the precision of your original measurement, so it cannot report significant figures for you.
- Units that share a name but differ by region or era (for example, different definitions of a gallon or a ton) are offered only in the variants listed in the unit menu.
- Very large or very small magnitudes are subject to the limits of double-precision floating-point arithmetic.
- It cannot convert between gauge and absolute pressure, which requires knowing the ambient pressure.