What is the best UV sensor?

If you mean UV sensors for an electronics project (Arduino, ESP32, Raspberry Pi, etc.), there isn't one universally “best” sensor—the right choice depends on whether you need UV Index, UVA/UVB, or spectral measurement.

My picks

DFRobot Gravity LTR390 UV Light Sensor

$13.16

SparkFun VEML6075 UV Light Sensor

$12.49

RAK12019 LTR390 UV Sensor

$4.00

Best overall for most projects: LTR390-UV-01

• Measures actual UV rather than estimating it from visible/IR light.
• Roughly 280–430 nm response.
• Digital I²C, making it easy with ESP32, Arduino, Raspberry Pi, etc.
• Also provides ambient-light measurement.
• Inexpensive and currently available on multiple breakout boards.www.adafruit.com

Best if you specifically need separate UVA + UVB: VEML6075. It has dedicated UVA and UVB sensing and calibration intended for UV-Index calculations. However, the VEML6075 has been discontinued by Vishay, so I wouldn't choose it for a new design unless you specifically need its characteristics.learn.adafruit.com

For serious spectral UV measurement: I'd look at the AS7331, which provides separate UVA, UVB, and UVC channels. That's a substantially different class of sensor from the inexpensive hobby modules.

Bottom line

If you tell me what you're measuring (sunlight, UV-C lamp, UV sterilizer, reptile lamp, 3D-printer curing, etc.) and your microcontroller, I can narrow it down to the specific sensor and breakout board I'd use.

The "best" UV sensor depends heavily on your project's requirements, such as whether you need simple analog readings, precise digital UV index values, or low power consumption for a weather station or wearable.

The top-rated UV sensors on the market categorized by use case include:

GUVA-S12SD (Best for Simple DIY / Analog Projects)

• Type: Analog output
• Spectral Range: 240 nm - 370 nm (covers UVB and most UVA)
• Why it’s great: Available widely as a breakout board (like the Adafruit Analog UV Light Sensor Breakout or ShillehTek GUVA-S12SD Module ). It gives a straightforward linear analog voltage output relative to UV intensity, making it extremely easy to hook up to an Arduino or ESP32 without complex I2C library configurations.

LTR390-UV (Best for Modern Digital & Precision UV Index)

• Type: Digital I²C output
• Why it’s great: A modern ambient light and ultraviolet light sensor that provides direct digital UV index values over an I²C interface. It features high sensitivity, excellent infrared rejection, and low power consumption, making it ideal for weather stations and smart-home setups compatible with Raspberry Pi, Arduino, or STM32.

Si1145 (Best Multi-Function / Ambient Light + UV)

• Type: Digital I²C output
• Why it’s great: While slightly more complex to configure than the GUVA-S12SD , the Si1145 can measure visible light, infrared light, and UV index simultaneously. It's great if your project requires general environmental tracking alongside UV exposure.[1][2][3]

To help me recommend the exact right sensor for you, tell me:

• What microcontroller or board are you using (e.g., Arduino, ESP32, Raspberry Pi)?
• Is this for an outdoor weather station , a wearable device , or a benchtop/indoor experiment?

If you mean an electronic UV sensor for an Arduino/ESP32/Raspberry Pi project, the choice depends on what you want to measure:

• Best general-purpose choice: LTR390-UV-01 — digital I²C, low cost, wide UV response, and also measures ambient light. It’s a particularly good fit for weather stations and outdoor monitoring.PCBSync+1

• Adafruit LTR390 UV Light Sensor - $5.30 (Pimoroni Ltd)

• Best for UVA/UVB differentiation: VEML6075 — has separate UVA and UVB channels and 16-bit digital output. However, independent testing found significant angular-response and calibration issues, so it shouldn't be treated as a precision radiometer without calibration.Frontiers

• Best for UVA/UVB/UVC spectral information: AS7331 — a more sophisticated three-channel sensor. This is the direction I'd look if you need to distinguish different UV bands rather than simply estimate UV intensity.

• Best cheap analog option: ML8511 — simple and easy to interface, but its response extends into visible wavelengths, making it less suitable when measurement accuracy matters.Frontiers

My recommendation

For a new DIY design, I'd start with the LTR390. For example, the DFRobot version provides I²C/UART and covers roughly 280–430 nm.DFRobot Electronics

If you tell me what UV source you're measuring (sunlight/UV index, 365 nm LEDs, 395 nm LEDs, UV-C at 254 nm, etc.) and your microcontroller, I can recommend the specific sensor and breakout board.

If you mean UV sensors for an electronics project, there isn't one universal “best”—it depends on whether you need UV Index, UVA/UVB/UVC measurement, or simply UV intensity.

My picks

• Best for UV Index / sunlight: VEML6075 — measures UVA and UVB separately, has 16-bit I²C output, and is specifically designed for UV Index calculations.Vishay+1

• Best current general-purpose choice: LTR390 — inexpensive, digital I²C, measures UV and ambient light, and is straightforward to use with Arduino/ESP32/Raspberry Pi.Adafruit+1

• Best if you need actual UVA/UVB/UVC spectral channels: AS7331 — more appropriate when distinguishing different UV bands matters.

• Best cheap analog sensor: GUVA-S12SD — simple analog output and roughly 240–370 nm response, but less convenient/precise than the digital sensors.

• LTR390 UV Light Sensor - $17.20 (newegg.com)

• Waveshare LTR390 UV Sensor - $35.99 (newegg.com)

• GUVA-S12SD Analog UV Sensor - $8.41 (The Pi Hut)

If I were building a new Arduino/ESP32 weather or sunlight monitor today, I'd generally choose the LTR390. The VEML6075 remains attractive for UV-Index applications, but some breakout boards are now discontinued.Adafruit

If you tell me what you're measuring (sunlight/UV Index, UV-C lamp, reptile lamp, resin curing, etc.) and your microcontroller, I can recommend the specific sensor and module.

If you mean an electronic UV sensor for an Arduino/ESP32/Raspberry Pi project, the LTR390-UV-01 is a strong choice for most new designs. It has digital I²C output, measures UV plus ambient light, and has a broad UV response around 280–430 nm.Adafruit+1

• Adafruit LTR390 UV Light Sensor - $17.20 (newegg.com)

Quick comparison

• LTR390 — best general-purpose choice; easy I²C interface and readily available.Adafruit Learning System
• AS7331 — better if you need more serious spectral measurement, with separate UVA/UVB/UVC channels. A university design comparison selected it for its flexibility and spectral capability.UCF Electrical and Computer Engineering
• VEML6075 — useful for dedicated UVA/UVB and UV-index measurement, but I wouldn't start a new design around it because the Adafruit breakout is no longer stocked.Adafruit Learning System+1
• GUVA-S12SD — inexpensive analog option if you just need a simple UV-intensity signal.

If you tell me what you're measuring—sunlight/UV Index, UV-C sterilization, a 365–405 nm UV LED, reptile lighting, plant lighting, etc.—I can tell you which sensor is actually the right one.

If you mean an electronic UV sensor for an Arduino/ESP32/Raspberry Pi project, my pick is:

• SparkFun Spectral UV Sensor - AS7331 (Qwiic) - $36.04 (The Pi Hut)

Best choices

• 🥇 AS7331 — best overall / highest capability. It has separate UVA, UVB, and UVC channels, making it much better if you need actual spectral information rather than just a rough UV level.MDPI
• 🥈 LTR390-UV-01 — best value and easiest choice. Digital I²C, good sensitivity, inexpensive, and measures UV plus ambient light. It's my recommendation for most ESP32/Arduino weather-station or outdoor UV-monitoring projects.
• 🥉 VEML6075 — good specifically for UV Index. It has separate UVA/UVB channels and calibration registers for calculating UVI, but I'd generally choose the LTR390 or AS7331 for a new design.Adafruit Learning System
• ML8511 — best cheap/simple analog option. Easy to interface, but its response includes some visible light and research has found that inexpensive UV sensors can require individual calibration.Frontiers+1

If I were building one today: LTR390 for a normal UV meter → AS7331 if accuracy/spectral information matters.

• LTR390 UV Sensor - $17.20 (newegg.com)
• AS7331 Spectral UV Sensor - $36.04 (The Pi Hut)
• ML8511 UV Sensor - $11.95 (Canada Robotix)
• GUVA-S12SD UV Sensor - $6.88 (RobotShop USA)

If you tell me what you're measuring (sunlight/UV Index, UV-C lamp, 365-nm LED, reptile lamp, resin curing, etc.), I can recommend the specific sensor and breakout board—the best choice changes quite a bit by application.