Frequency Converter — Hz, kHz, MHz, GHz, RPM & More

Divide RPM by 60 to get Hz. Multiply Hz by 60 to get RPM. Examples: 3,600 RPM ÷ 60 = 60 Hz. 50 Hz × 60 = 3,000 RPM. Common motor speeds: 1,800 RPM (30 Hz) for 4-pole motors on 60 Hz power, 1,500 RPM (25 Hz) for 4-pole motors on 50 Hz power. This relationship is fundamental for electric motor selection, pump sizing, and conveyor belt design.

The choice is historical — Westinghouse/Tesla standardized 60 Hz in the US for better lighting performance (less visible flicker), while AEG/European systems adopted 50 Hz for metric convenience (50 Hz aligns well with 1,500 RPM synchronous motors). 60 Hz provides about 20% more power delivery for the same transformer size but results in slightly higher transmission losses. Aircraft use 400 Hz because it allows dramatically smaller and lighter transformers and motors — a 400 Hz transformer is about 1/8 the weight of a 60 Hz unit. Both 50 Hz and 60 Hz work fine for most applications, but 50 Hz equipment run on 60 Hz power (or vice versa) will operate at the wrong speed.

WiFi primarily uses the 2.4 GHz and 5 GHz bands. 2.4 GHz (2,400 MHz) penetrates walls better and has longer range but is more congested — shared with Bluetooth, microwaves, and cordless phones. 5 GHz (5,150-5,850 MHz) offers faster speeds and less interference but shorter range and poorer wall penetration. The newer 6 GHz band (WiFi 6E/7) adds more spectrum for extremely fast, low-latency connections. Each band is divided into channels — 2.4 GHz has 14 channels of 20 MHz each (with only 3 non-overlapping). 5 GHz offers more channels with 20, 40, 80, or 160 MHz width for higher speeds.

A healthy young human can hear approximately 20 Hz to 20,000 Hz (20 kHz). With age, the upper limit typically drops to 15-17 kHz by age 40, and 12-14 kHz by age 60. Sub-bass (20-60 Hz) is felt more than heard — this is the range of kick drums and explosions. Midrange (250-4,000 Hz) contains most speech and instrument fundamentals — the most critical range for hearing. The highest octave (10-20 kHz) contains harmonics and "air" in audio but is the first range lost with age or hearing damage. Professional audio equipment typically operates at sample rates of 44.1 kHz (CD quality) or 48 kHz, capturing frequencies up to about 22-24 kHz.

The radio spectrum is divided into bands by frequency: VLF (3-30 kHz) for submarine communication. LF (30-300 kHz) for navigation beacons and time signals. MF (300-3,000 kHz) for AM radio (530-1,700 kHz). HF (3-30 MHz) for international shortwave broadcasting, amateur radio, and aviation. VHF (30-300 MHz) for FM radio (88-108 MHz), broadcast TV, and air traffic control. UHF (300-3,000 MHz) for cellular, WiFi, Bluetooth, GPS, and TV. SHF (3-30 GHz) for satellite, 5G mmWave, and radar. EHF (30-300 GHz) for high-speed communications and radio astronomy. Each band has different propagation characteristics — lower frequencies travel farther and penetrate buildings better, while higher frequencies carry more data.