Fidamen

Convert Hertz to RPM - Frequency Converter

This converter converts between frequency (hertz, Hz) and rotational speed (revolutions per minute, RPM). The direct mathematical relationship for pure unit conversion is fixed and lossless: 1 Hz equals 60 RPM.

Beyond the simple ratio, practical use cases include converting electrical frequency to motor synchronous speed (which depends on pole count), translating encoder pulse rates to RPM, and setting VFD or instrument setpoints. Where measurement accuracy matters, consult calibration practices and instrument limits.

The guidance and examples that follow reference recognized standards and technical resources from government laboratories and leading universities to support reliable results and safe application.

Updated Nov 24, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 26b6c1473773 • Reviewed by Fidamen Standards Committee

Interactive Converter

Convert between hertz and revolution per minute with precision rounding.

Quick reference table

HertzRevolution per Minute
1 HzRPM 60.00 rpm
5 HzRPM 300.00 rpm
10 HzRPM 600.00 rpm
25 HzRPM 1,500.00 rpm
50 HzRPM 3,000.00 rpm
100 HzRPM 6,000.00 rpm

Methodology

Direct unit conversion: multiply Hz by 60 to get RPM, divide RPM by 60 to get Hz. This is the canonical SI relationship and is exact for a single-cycle-per-revolution system.

Electric motors — synchronous speed: mechanical synchronous RPM depends on electrical frequency and the number of motor poles. Use the synchronous speed formula below and account for slip in induction motors when estimating actual running speed.

Encoders and pulse-based measurements: when a sensor emits multiple pulses per revolution, divide measured pulses-per-second by pulses-per-revolution, then multiply by 60 to get RPM. Follow instrument manufacturer calibration intervals and NIST guidance for traceability when accuracy is required.

Worked examples

1 Hz → 60 RPM (1 × 60 = 60).

50 Hz → 3000 RPM on a 2-pole synchronous shaft (120 × 50 ÷ 2 = 3000).

60 Hz → 3600 RPM on a 2-pole synchronous shaft (120 × 60 ÷ 2 = 3600).

Encoder example: 1000 pulses per second from a sensor with 20 pulses per revolution → RPM = (1000 ÷ 20) × 60 = 3000 RPM.

F.A.Q.

What is the exact relationship between hertz and RPM?

The exact SI relationship is RPM = Hz × 60. One hertz is one cycle per second; multiplying by 60 converts cycles per second to cycles per minute, which equals revolutions per minute for a one-cycle-per-revolution system.

How do I convert electrical frequency to motor RPM when pole count matters?

Use synchronous speed = (120 × f) ÷ P, where f is electrical frequency (Hz) and P is the motor pole count. For induction motors, actual running speed will be slightly lower due to slip; estimate actual speed as synchronous speed × (1 − slip).

Can I use Hz → RPM conversion for VFD setpoints?

Yes. For a simple shaft speed target, calculate the required electrical frequency from desired RPM (Hz = RPM ÷ 60 for a 2-pole motor equivalently using the synchronous formula with P). Always verify motor nameplate pole count and follow VFD manufacturer guidance and safety lockout procedures before applying changes.

How precise is the conversion? What about measurement uncertainty?

The mathematical conversion is exact, but practical precision depends on measurement instrument resolution, sampling rate, and calibration. Oscilloscopes, frequency counters, and encoders have defined uncertainties; follow NIST traceability and calibration intervals for measurements used in certification or safety-critical applications.

How do I convert pulses from an encoder to RPM?

Calculate revolutions per second as pulses per second divided by pulses per revolution, then multiply by 60 to get RPM. For noisy or aliasing-prone signals, use averaging or high-resolution timers and ensure sensor wiring and shielding meet manufacturer recommendations.

Are there safety or regulatory considerations when changing motor speeds?

Yes. Changing speed can affect torque, cooling, and connected machinery. Follow OSHA machine safety guidance, motor manufacturer recommendations, and applicable industry standards. For regulated environments or critical systems, consult qualified personnel and documented procedures before altering speeds.

Sources & citations

Further resources

Versioning & Change Control

Audit record (versions, QA runs, reviewer sign-off, and evidence).

Record ID: 26b6c1473773

What changed (latest)

v1.0.0 • 2025-11-24 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Public QA status

PASS — golden 25 + edge 120

Last run: 2026-01-23 • Run: golden-edge-2026-01-23

Engine

v1.0.0

Data

Baseline (no external datasets)

Content

v1.0.0

UI

v1.0.0

Governance

Last updated: Nov 24, 2025

Reviewed by: Fidamen Standards Committee (Review board)

Credentials: Internal QA

Risk level: low

Reviewer profile (entity)

Fidamen Standards Committee

Review board

Internal QA

Entity ID: https://fidamen.com/reviewers/fidamen-standards-committee#person

Semantic versioning

  • MAJOR: Calculation outputs can change for the same inputs (formula, rounding policy, assumptions).
  • MINOR: New features or fields that do not change existing outputs for the same inputs.
  • PATCH: Bug fixes, copy edits, or accessibility changes that do not change intended outputs except for previously incorrect cases.

Review protocol

  • Verify formulas and unit definitions against primary standards or datasets.
  • Run golden-case regression suite and edge-case suite.
  • Record reviewer sign-off with credentials and scope.
  • Document assumptions, limitations, and jurisdiction applicability.

Assumptions & limitations

  • Uses exact unit definitions from the Fidamen conversion library.
  • Internal calculations use double precision; display rounding follows the unit's configured decimal places.
  • Not a substitute for calibrated instruments in regulated contexts.
  • Jurisdiction-specific rules may require official guidance.

Change log

v1.0.0 • 2025-11-24 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Areas: engine, content, ui • Reviewer: Fidamen Standards Committee • Entry ID: 70727b5de05c