What is vibration acceleration?

Vibration acceleration is the rate of change of vibration velocity, measured in m/s² or g (where 1 g = 9.80665 m/s²). It is the most sensitive parameter to high-frequency vibration and is critical for detecting bearing defects, gear mesh faults, and other high-frequency mechanical problems. Acceleration increases with both vibration amplitude and frequency.

When should I use acceleration instead of velocity for vibration monitoring?

Acceleration is preferred for high-frequency vibration analysis, typically above 1000 Hz. It is the best parameter for early detection of rolling element bearing defects, gear mesh problems, and cavitation. Velocity (mm/s RMS) is better for general machine condition in the 10–1000 Hz range, while displacement is preferred below 10 Hz. Many modern condition monitoring systems use acceleration enveloping (demodulation) for bearing diagnostics.

How do I convert g to m/s²?

To convert from g to m/s², multiply by 9.80665 (standard gravity). For example, 0.5 g = 0.5 × 9.80665 = 4.903 m/s². Conversely, to convert m/s² to g, divide by 9.80665. The g unit is commonly used in vibration analysis because typical industrial vibration levels fall in a convenient range of 0.01 to 50 g.

What sensors measure vibration acceleration?

Piezoelectric accelerometers are the standard sensors for measuring vibration acceleration. IEPE (ICP) type accelerometers with integrated electronics are most common in industrial applications. They offer wide frequency range (0.5 Hz to 20 kHz+), high sensitivity, and excellent durability. MEMS accelerometers are used in lower-cost monitoring systems but typically have more limited frequency range and accuracy. Charge-mode accelerometers are used for high-temperature applications.

What is typical vibration acceleration for industrial machines?

Typical vibration acceleration levels vary widely with machine type and frequency. For general industrial machinery at operating speed: good condition is below 0.5 g, acceptable is 0.5–2 g, and alarm levels are typically 2–5 g at bearing housings. High-frequency bearing defect signals can reach 10–50 g peak. ISO 20816 primarily uses velocity for zone evaluation, but acceleration is measured directly by accelerometers and is essential for high-frequency diagnostics.

Free Engineering Tool

Vibration Acceleration Calculator (ISO 20816)

Convert vibration velocity (mm/s RMS) to acceleration (m/s², g) at any frequency. Enter velocity and frequency to get acceleration RMS, peak, and displacement results.

ISO 20816 m/s² & g Hz / RPM

Results

Acceleration RMS

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Acceleration Peak

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Acceleration RMS (g)

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Acceleration Peak (g)

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Velocity RMS

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Velocity Peak

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Displacement Peak-to-Peak

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Frequency

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Acceleration from Velocity

For sinusoidal vibration, acceleration is derived from velocity by multiplication with angular frequency:

Conversion to g

Displacement from Velocity

Where:

v_RMS — vibration velocity RMS (mm/s)
f — frequency (Hz); if RPM given: f = RPM / 60
a_RMS — acceleration root mean square (m/s²)
a_peak — acceleration peak = a_RMS × √2 (m/s²)
d_pp — displacement peak-to-peak (μm)

Practical Example

Example — 4.5 mm/s RMS at 25 Hz

a_RMS = 4.5 × 2π × 25 / 1000 = 0.707 m/s²

a_peak = 0.707 × √2 = 1.000 m/s²

a_g,RMS = 0.707 / 9.80665 = 0.072 g

d_pp = 4.5 × √2 × 1000 / (π × 25) = 81.0 μm

Vibration Parameter Comparison

Parameter	Best Frequency Range	Typical Units	Primary Use
Displacement	< 10 Hz (600 RPM)	μm p-p	Low-speed machines, shaft vibration
Velocity	10–1000 Hz	mm/s RMS	General machine condition (ISO 10816)
Acceleration	> 1000 Hz	m/s², g	Bearing defects, gear mesh, high-freq

Vibration Acceleration Calculator — mm/s to m/s² & g

Results

Acceleration from Velocity

Conversion to g

Displacement from Velocity

Practical Example

Vibration Parameter Comparison

Nikolai Shelkovenko

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