# J-UV

> UV index meter that plugs into iPhone/iPad audio jack for real-time measurement. (iPhone/iPad app by Kwan Shing Marco Li.)

- Source: https://appshunter.io/ios/app/j-uv/id1073037537 (this page in markdown: same URL + `.md`)
- Developer: [Kwan Shing Marco Li](https://appshunter.io/developer/987891587)
- Category: Utilities, Weather
- Price: Free
- Rating: 3.00/5 from 2 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 8.0 · 1 MB
- Languages: English
- Released: 2016-01-22
- Data updated: 2026-06-10
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/j-uv/id1073037537/reviews.md

## What is J?

J-UV is an UV index meter that plugs into audio jack of your iPhone/iPad. 

Features:
-Plug and Play! No setup required
-Measurement range from UVI 0 to 11+
-Real-time UV Index measurement
-UV protection for reference
-No battery required

How to use:
1.  Open "J-UV" app.

2. Firmly plug the J-UV into the audio jack of iPhone/iPad and turn the headphone volume to maximum.The UV index reading shall be shown in a few seconds. 

3. When you finished using J-UV, press "Done", then plug out J-UV from iPhone/iPad.


Troubleshooting:
If the J-UV is not showing the UVI reading, please check the following:
-If the app shows "No J-UV detected" or "No data from J-UV", please manually turn the headphone volume to maximum.
-If the app shows "Cannot access microphone due to privacy setting", then please turn ON the microphone accessibility in privacy setting for "J-UV" app.
-Please make sure "Volume Limit" is turned off in "Settings" of iPhone/iPad.
-For iPhone/iPad purchased in EU, the EU volume limit may apply to devices which means the headphone volume maybe lower, therefore it is not guaranteed that J-UV will work. If there is "EU Volume Limit" in "Settings", please turn it off and try.

Contact us:
If you have any enquiries, please contact
marco@carrin.com.hk

## Key features

- Plugs into audio jack
- Real-time UV Index measurement
- Measurement range 0-11+
- No battery required
- Plug and Play setup

## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/j-uv/id1073037537/reviews.md

### 1/5 — Why hasn't this been removed ?

*2020-04-09, version 1.4.0*

Useless

## Frequently asked questions about J

### What is J-UV?

J-UV is a utility application that works with a physical sensor to measure the UV index. It plugs into the audio jack of your iPhone or iPad, providing real-time UV index readings.

### How do I use J-UV?

To use J-UV, plug the sensor firmly into your device's audio jack, turn the headphone volume to maximum, and open the J-UV app. The UV index reading will appear within seconds.

### Does J-UV require a battery?

No, J-UV does not require a battery. It draws power directly from your iPhone or iPad through the audio jack connection.

### What is the measurement range of J-UV?

J-UV can measure UV index levels ranging from 0 to 11+. This provides a comprehensive overview of UV radiation intensity.

### What should I do if J-UV is not showing a reading?

If J-UV is not showing a reading, ensure the headphone volume is at maximum. Also, check privacy settings to confirm microphone access is enabled for the J-UV app and that 'Volume Limit' is turned off in your device's settings.

### Is J-UV compatible with all iPhones and iPads?

J-UV is designed for iPhone, iPad, and iPod. However, devices purchased in the EU might have a volume limit that could affect J-UV's functionality. Turning off the 'EU Volume Limit' in settings may resolve this.

### What is the rating of J-UV?

J-UV has a rating of 3.0 stars based on 2 user ratings.

### When was J-UV last updated?

J-UV was last updated on March 11, 2016, with version 1.4.0.

## Version history (last 1 release)

### 1.4.0 — 2016-03-11

This app has been updated by Apple to display the Apple Watch app icon.

minor bug fixed.

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## More apps by Kwan Shing Marco Li

- [J-Thermo](https://appshunter.io/ios/app/j-thermo/id987891588)
- [J-TH](https://appshunter.io/ios/app/j-th/id1148916918)
- [BLE Thermo-Hygrometer](https://appshunter.io/ios/app/ble-thermo-hygrometer/id1164144654)

All apps by Kwan Shing Marco Li: https://appshunter.io/developer/987891587

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*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 2026-06-10.*