# Frequency Counter+ Hz FFT — Tuner · RPM · 50/60Hz Meter

> iPhone audio analyzer for frequency measurement, instrument tuning, and motor RPM analysis. (iPhone/iPad app by Kyu-Hee Jang.)

- Source: https://appshunter.io/ios/app/frequency-counter-plus-hz-fft/id6761234058 (this page in markdown: same URL + `.md`)
- Developer: [Kyu-Hee Jang](https://appshunter.io/developer/1587578867)
- Category: Utilities, Productivity
- Price: Free
- Rating: 3.30/5 from 6 App Store ratings · 2 written reviews indexed
- Age rating: 17+
- Requires: iOS 17.0 · 69 MB
- Languages: American English
- Released: 2026-03-31
- Data updated: 2026-08-19
- Monetization: ad-supported
- User reviews in markdown: https://appshunter.io/ios/app/frequency-counter-plus-hz-fft/id6761234058/reviews.md

## What is Frequency Counter+ Hz FFT?

Frequency Counter+ turns your iPhone into a precise audio analyzer with four purpose-built modes. Measure the dominant frequency of any sound, tune an instrument, read motor RPM by ear, or check the stability of your 50/60 Hz mains.

FOUR MODES
• Music — instrument tuner showing note name (A4, F#5) and cents off pitch (A4=440 Hz).
• Motor — RPM displayed first, with hints for 1500/1800/3000/3600 RPM standards.
• Hum — 50/60 Hz mains lock with deviation in ±0.01 Hz.
• Auto — Hz reading with closest musical note or mains harmonic shown live.

WHAT'S NEW
• Measurement History — every reading is auto-saved with a 7-day trend chart and insights like "+12% vs your 7-day average".
• Notes & Favorites — add a note ("fridge", "room 1") and star to any saved reading.
• Compare Mode — pick two saved measurements and view the difference side by side.
• Calibration Offset — fine-tune your microphone in ±0.1 Hz steps.
• Share Result — share your current frequency reading as an image.
• CSV Export — share all your measurements as CSV for spreadsheets.

CORE FEATURES
• Precise dominant frequency measurement (Hz)
• Large multimeter-style digital display
• Automatic 50/60 Hz mains hum detection with lock indicator
• Instant Hz-to-RPM conversion
• Waveform and amplitude visualization
• Microphone calibration

FOR MUSICIANS · AUDIO ENGINEERS · ELECTRICIANS · MECHANICS · HVAC TECHS · INDUSTRIAL DIAGNOSTICS

Available in 14 languages.

## Key features

- Dominant frequency measurement (Hz)
- Instrument tuning with note and pitch display
- Motor RPM analysis
- 50/60 Hz mains hum detection
- Measurement history and trend charts
- CSV export of measurements

## Recent user reviews (2 of 2)

All indexed reviews: https://appshunter.io/ios/app/frequency-counter-plus-hz-fft/id6761234058/reviews.md

### 1/5 — The first ad that came up led me to a scam

*2026-08-14*

Tried to scam me

**Developer response:** That should never have happened and I am sorry it was your first experience of the app. The ads come from Google's ad network rather than from us, but a scam creative is not acceptable and I am reporting it so it can be blocked. Thank you for flagging it - reports like yours are the only way these get caught.

### 3/5 — Too many ads

*2026-08-10*

The app works for what I needed, works to test hair clipper rpms. But sometimes the ads get in the way and you can’t even remove them

**Developer response:** Thanks — clipper RPM is a good use for this, and I appreciate the detail.

On the ad: I tested it and the banner does open expanded over the readouts. There's a small collapse arrow at its top-right that shrinks it, but it reopens each session, so you'd be tapping it every time you measure. I'd rather not pretend that's a fix.

If you meant you'd like a way to remove ads entirely, there isn't one today — that's fair feedback and I'm looking at it. Thanks for taking the time to write.

## Frequently asked questions about Frequency Counter+ Hz FFT

### What is Frequency Counter+ Hz FFT?

Frequency Counter+ Hz FFT is a utility app that uses your iPhone's microphone to analyze audio frequencies. It offers modes for instrument tuning, motor RPM measurement, and mains hum detection.

### Does Frequency Counter+ Hz FFT have ads?

Yes, Frequency Counter+ Hz FFT contains advertisements. As it is a free application, ads are used to support its development and maintenance.

### What devices does Frequency Counter+ Hz FFT support?

Frequency Counter+ Hz FFT is available for iPhone and iPod touch devices. It is designed to utilize the microphone capabilities of these Apple products.

### How accurate is the frequency measurement in Frequency Counter+ Hz FFT?

The app provides precise dominant frequency measurement in Hz. It also includes microphone calibration to fine-tune accuracy in ±0.1 Hz steps.

### Can I save and compare measurements with Frequency Counter+ Hz FFT?

Yes, Frequency Counter+ Hz FFT automatically saves readings with a 7-day trend chart. You can add notes, mark favorites, and use the Compare Mode to view differences between saved measurements.

### What is the age rating for Frequency Counter+ Hz FFT?

Frequency Counter+ Hz FFT has an age rating of 17+. This rating is determined by app store guidelines and may reflect the complexity or potential use cases of the application.

### How often is Frequency Counter+ Hz FFT updated?

The latest version of Frequency Counter+ Hz FFT is 1.0.24, last updated on June 19, 2026. Updates typically bring new features, bug fixes, and performance improvements.

### Can I export my frequency data from Frequency Counter+ Hz FFT?

Yes, Frequency Counter+ Hz FFT supports CSV export, allowing you to share all your saved measurements for use in spreadsheets or other data analysis tools.

## Version history (last 5 releases)

### 1.0.41 — 2026-08-17

The Hum reading is now a true 0.01 Hz measurement: the app times the mains waveform across about a hundred cycles instead of rounding to a tenth. Stopping the tuner or the ultrasonic sweep no longer flashes a full-screen ad under your finger.

Thanks for the reviews and feedback!

### 1.0.40 — 2026-08-15

The interstitial now appears when a measurement finishes rather than when one begins, so it no longer lands in the middle of what you were reading. The app also stops fetching ads it will not use at launch, which makes startup lighter, and the opening ad is no longer discarded when it arrives a moment late.

### 1.0.39 — 2026-08-11

If you ever measured a high tone and thought the number looked too high, it was. The spectrum's labels were drawn as though the scale ran to 22 kHz, but the analyser only works up to a quarter of the sample rate — around 11 kHz. A 10 kHz tone could read back as 19.6 kHz. The labels now come from the analyser's own frequency bins and follow your device's real sample rate, so the number you read is the number you measured.

The tuner now respects your concert pitch. The guitar, bass, ukulele and violin presets sat at A4 = 440 Hz no matter what you had set, so anyone tuned to 432 was told that every correctly tuned string was sharp. The presets now move with your A4, and each string shows its target frequency — the setting is finally visible where it applies.

Two smaller things: a Bluetooth headset that takes a few seconds to connect is no longer mistaken for a broken microphone, and Freeze now holds the peak list and THD along with the bars.

### 1.0.38 — 2026-08-06

Ads no longer interrupt you mid-task. Anything full-screen now waits until you have finished what you were doing, and the app stops showing a blank pause where an ad failed to load.

### 1.0.37 — 2026-08-06

Starting a measurement is no longer interrupted — the app gets straight to work, and anything that needs your attention waits until you are done.

## More apps by Kyu-Hee Jang

- [Calculator+ Tip Tax BMI Unit](https://appshunter.io/ios/app/calculator-plus-tip-tax-bmi-unit/id1587591476)
- [QR Lens+ Barcode Scanner Pro](https://appshunter.io/ios/app/qr-lens-plus-barcode-scanner-pro/id1590631012)
- [Sound Noise Meter+ dB SPL](https://appshunter.io/ios/app/sound-noise-meter-plus-db-spl/id1593197145)
- [Tremor Vibration Meter](https://appshunter.io/ios/app/tremor-vibration-meter/id6759666731)
- [Lux Light Meter - Luminance](https://appshunter.io/ios/app/lux-light-meter-luminance/id6759858193)
- [Barometer: Air Pressure](https://appshunter.io/ios/app/barometer-air-pressure/id6759883097)

All apps by Kyu-Hee Jang: https://appshunter.io/developer/1587578867

## Related topics

[frequency counter](https://appshunter.io/ios/topics/frequency-counter) · [hertz meter](https://appshunter.io/ios/topics/hertz-meter) · [frequency meter](https://appshunter.io/ios/topics/frequency-meter) · [hz frequency measure](https://appshunter.io/ios/topics/hz-frequency-measure) · [hz frequency reader](https://appshunter.io/ios/topics/hz-frequency-reader) · [hertz frequency measure](https://appshunter.io/ios/topics/hertz-frequency-measure) · [free frequency detector](https://appshunter.io/ios/topics/free-frequency-detector) · [frequency analyzer hz](https://appshunter.io/ios/topics/frequency-analyzer-hz) · [hz detector](https://appshunter.io/ios/topics/hz-detector) · [hertz frequency detector](https://appshunter.io/ios/topics/hertz-frequency-detector) · [hzdetect](https://appshunter.io/ios/topics/hzdetect) · [frequency meter light](https://appshunter.io/ios/topics/frequency-meter-light) · [audio frequency analyzer free](https://appshunter.io/ios/topics/audio-frequency-analyzer-free) · [60hz](https://appshunter.io/ios/topics/60hz) · [frequency detector](https://appshunter.io/ios/topics/frequency-detector) · [frequency detector tool](https://appshunter.io/ios/topics/frequency-detector-tool) · [hz frequency detector](https://appshunter.io/ios/topics/hz-frequency-detector) · [hz frequency tuner](https://appshunter.io/ios/topics/hz-frequency-tuner) · [sound measure frequency](https://appshunter.io/ios/topics/sound-measure-frequency) · [audio frequency analyzer](https://appshunter.io/ios/topics/audio-frequency-analyzer)

---

*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-19.*