What is vibration velocity RMS?

Vibration velocity RMS (root mean square) is the standard metric for quantifying vibration energy. For a sinusoidal signal it equals peak velocity divided by the square root of 2, or equivalently 2π × frequency × peak displacement divided by √2. It correlates well with bearing and structural fatigue damage.

What does ISO 10816 define?

ISO 10816 (now updated as ISO 20816) defines evaluation criteria for machine vibration measured on non-rotating parts. It groups velocity RMS into four zones: A (new machine, acceptable), B (unrestricted long-term operation), C (conditional short-term operation), D (danger — shut down).

Which machine class should I use?

ISO 10816-3 distinguishes large machines (>15 kW, rigid or flexible mounting) and medium machines (15–300 kW). The zone thresholds differ by class. This tool shows the most common thresholds for reference; always verify against the applicable part of the standard for your specific machinery.

Why do I get different results from displacement vs peak velocity input?

Both methods apply the same physics. Displacement input uses v_rms = 2π × f × A / √2 where A is peak displacement. Peak velocity input uses v_rms = v_peak / √2. If you get different numbers, check that your displacement reading is true peak (not peak-to-peak) and that frequency matches the dominant vibration frequency.

What units does this calculator use?

Displacement input accepts millimeters (mm) or micrometers (µm). Frequency is in Hz. Peak velocity input accepts mm/s. The output is always mm/s RMS, consistent with ISO 10816 reporting.

Vibration Velocity RMS Calculator

Name: Vibration Velocity RMS Calculator
Availability: InStock
Author: Nham Vu

Calculate vibration velocity RMS from displacement amplitude and frequency, or from peak velocity, then classify severity per ISO 10816 zones.

Input

Input mode

Displacement + Frequency Peak Velocity

Peak displacement amplitude

Frequency

Formulas

v_rms = (2π × f × A) / √2 (from displacement)

v_rms = v_peak / √2 (from peak velocity)

A = peak displacement, f = frequency in Hz

Result

Enter values and click Calculate

ISO 10816 Severity Zones (mm/s RMS)

Zone	Large machines rigid mount >300 kW	Medium machines 15–300 kW	Assessment
A	< 2.3	< 1.4	New — acceptable
B	2.3 – 4.5	1.4 – 2.8	Unrestricted long-term operation
C	4.5 – 7.1	2.8 – 4.5	Conditional — short-term only
D	> 7.1	> 4.5	Danger — shut down

Reference: ISO 10816-3 (large/medium machines on rigid mounts). Thresholds vary by machine class and mounting; consult the applicable standard for your equipment.

Summary

Calculate vibration velocity RMS from displacement amplitude and frequency, or from peak velocity, then classify severity per ISO 10816 zones.

How it works

Select input mode: displacement (amplitude + frequency) or peak velocity.
Enter values with appropriate units.
Click Calculate to compute the RMS velocity in mm/s.
The tool displays the result with an ISO 10816 severity zone badge.
Use the zone reference table to interpret condition acceptability for your machine class.

Use cases

Screen vibration levels of pumps, fans, and compressors during routine condition monitoring rounds.
Determine whether a newly commissioned machine meets ISO 10816 acceptance criteria before sign-off.
Convert displacement readings from a proximity probe to velocity RMS for trend comparison.
Convert peak velocity readings from a handheld vibration meter to RMS for report standardization.
Quickly classify machine severity during a walk-around inspection without spreadsheet lookup.

Frequently Asked Questions

Last updated: 2026-07-26 · Reviewed by Nham Vu