Hydraulics & Fluid Power Reference Library · Wall Charts

Pressure Unit Conversion Chart

Conversion factors between psi, bar, MPa and kPa, with lookup tables for common hydraulic pressures. Unit conversions only; no component pressure ratings are given.

Ref HY-0054NIST SP 811

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

Hydraulic pressures are stated in psi on North American equipment, in bar on most European and Asian equipment, and in MPa on many ISO standards and data sheets. This chart converts between them. It does not give ratings for any hose, fitting or component. Get those from the component marking and the maker's data.

How to use it

psi to bar: multiply by 0.06895.
bar to psi: multiply by 14.504.
MPa to bar: multiply by 10.
MPa to psi: multiply by 145.04.
kPa to psi: multiply by 0.1450.
psi to kPa: multiply by 6.895.

psi to bar and MPa

psi	bar	MPa
100	6.9	0.69
500	34.5	3.45
1,000	68.9	6.89
1,500	103.4	10.34
2,000	137.9	13.79
2,500	172.4	17.24
3,000	206.8	20.68
4,000	275.8	27.58
5,000	344.7	34.47
6,000	413.7	41.37
10,000	689.5	68.95

bar to psi

bar	psi	MPa
10	145	1.0
100	1,450	10.0
160	2,321	16.0
210	3,046	21.0
250	3,626	25.0
315	4,569	31.5
350	5,076	35.0
420	6,092	42.0

Key points

Gauge vs absolute: psig and bar(g) read zero at atmospheric pressure. psia and bar(a) read zero at a perfect vacuum. Standard atmosphere is 14.696 psi, 1.01325 bar or 101.325 kPa.
Hydraulic gauges and component ratings are almost always gauge pressure.
Round only at the end of a calculation. Rounding at each step adds error.
When a rating is printed in both units, the two values are often rounded and may not match exactly. Use the value in the governing standard's units.

Common mistakes

Dividing when you should multiply (bar to psi multiplies by about 14.5).
Confusing MPa with bar. 1 MPa is 10 bar.
Mixing gauge and absolute readings in the same calculation.

Governing standards: NIST SP 811 (unit conversion factors); component manufacturer data for all pressure ratings.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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