Verification: factors follow standard unit definitions; round for display only.

Hz to RPM

Convert Hz to RPM when a VFD datasheet, oscilloscope FFT, or power-line frequency lists hertz but a motor nameplate, fan curve, or machine-shop dial quotes revolutions per minute.

Hertz (Hz) counts cycles per second; revolutions per minute (RPM) counts full turns per minute. Because 1 min = 60 s, one cycle each second equals sixty revolutions over a full minute:

This site anchors frequency to hertz in the shared catalog. From those definitions (Hertz: 1, RPM: 0.0166666667):

RPM = Hz × 60  ·  catalog ratio 1 ÷ 0.0166666667

The live converter applies the full floating-point ratio. 60 equals 60 at catalog precision—electrical line frequency maps directly to synchronous speed for a two-pole machine.

Step-by-step conversion (worked example — 60 Hz line)

A two-pole induction motor on a 60 Hz supply has synchronous speed:

1. Write the formula: RPM = Hz × 60
2. Multiply: 60 × 59.999999880000004 = 3600 RPM
3. Actual slip drops measured RPM slightly below synchronous—compare nameplate rated speed, not just the Hz→RPM factor.

Second worked example (50 Hz, European grid)

A machine exported for 50 Hz service:

1. 50 × 59.999999880000004 = 3000 RPM
2. Two-pole synchronous anchor—3000 RPM before slip.

Third worked example (120 Hz VFD output)

A variable-frequency drive runs a spindle at 120 Hz:

1. 120 × 59.999999880000004 = 7200 RPM

Always confirm pole count—four-pole motors run at half the two-pole synchronous RPM for the same Hz.

Quick mental estimate

Multiply Hz by 60 for RPM on a two-pole synchronous basis. Example: 1 Hz → 60 RPM. Reverse: divide RPM by 60 for Hz. Remember 60 Hz → 3600 RPM and 50 Hz → 3000 RPM as shop-floor anchors.

Hertz to RPM conversion chart (catalog exact)

Where Hz → RPM comes up

• AC motors: Line frequency and pole count set synchronous RPM; VFD output in Hz maps to shaft speed through this factor (adjusted for poles).
• Rotating machinery: Vibration FFT peaks in Hz convert to RPM for balance reports and tachometer comparison.
• Audio / turntables: Rotational speed specs (33⅓ RPM, 45 RPM) relate to fractional Hz when analyzing wow/flutter—divide RPM by 60 for equivalent Hz.
• Process equipment: Agitator and centrifuge curves may mix Hz drive settings with RPM mechanical limits—align units before comparing to nameplate max.

RPM to Hz

Convert RPM to Hz when a motor nameplate, fan label, or machine log lists revolutions per minute but your VFD parameter set, FFT plot, or PLC trend stores hertz.

Divide by 60 (or multiply by 0.0166667). Both directions share the same minute-to-second relationship.

Hz = RPM ÷ 60  ·  equivalently   Hz = RPM × 0.0166667

Step-by-step conversion (worked example)

A pump nameplate shows 1750 RPM at full load. Convert to Hz for a four-pole slip estimate:

1. Divide: 1750 ÷ 59.999999880000004 = 29.1667 Hz
2. Compare to 60 Hz line—slip is expected; synchronous four-pole would be 1800 RPM at 60 Hz.

Second worked example (3600 RPM)

A two-pole synchronous machine at rated speed:

1. 3600 ÷ 59.999999880000004 = 60 Hz

Quick mental estimate (reverse)

Divide RPM by 60. Example: 1800 RPM → 30 Hz equivalent cycle rate (not the same as line frequency without pole math). For direct Hz↔RPM on one revolution per cycle: 3600 RPM = 60 Hz.

Quick reference (RPM → Hz)

Reverse conversion is essential when importing tachometer RPM logs into vibration software that integrates frequency in hertz.

Hz vs RPM, pole pairs, mistakes, and related tools

The Hz–RPM factor is exactly 60 when one mechanical revolution equals one electrical cycle. Account for pole count on motors; verify round-trips before locking VFD limits.

Hz vs RPM at a glance

Common mistakes to avoid

• Ignoring pole count on motors—60 Hz is 3600 RPM only for two-pole synchronous; four-pole is 1800 RPM at the same line frequency.
• Confusing RPM with rad/s—angular velocity in radians per second is a different unit family; use angle converters when the document specifies radians.
• Mixing Hz with kHz/MHz RF labels—radio carrier frequencies are not shaft RPM; confirm the quantity before converting.
• Double rounding on multi-stage gearboxes—convert input Hz to RPM at full precision, apply gear ratio, then round the output speed for the operator display.

Exactness and round-trip verification

Converting 60 Hz → RPM → Hz should recover 60 within floating-point limits. Anchor pairs: 1 Hz = 60 RPM; 60 Hz = 3600 RPM; 3600 RPM = 60 Hz.

Related frequency converters

For the inverse route, see RPM to hertz. Nearby workflows: hertz to kilohertz, hertz to megahertz, kilohertz to hertz, and megahertz to kilohertz.