Description
Reviews
| Brand | - |
| Category | Robotics / STEM Teaching Tools / Sensors |
| Origin | - |
| Sensor Type | HTU21D Digital Humidity & Temperature |
| Interface | I2C (Inter-Integrated Circuit) |
| Operating Voltage | 3.3V to 5.5V DC |
| Humidity Range | 0% to 100% RH |
| Temperature Range | -40°C to +125°C |
| Humidity Accuracy | ±2% RH (at 25°C) |
| Temperature Accuracy | ±0.3°C (at 25°C) |
| Response Time | 5 seconds (typical) |
| Board Dimensions | 14mm x 9mm x 2mm |
| Package Includes | 1x GY-21 Module, 1x Pin Header Strip |
Anonymous
Mar 31, 2026
Rating: 5/5
Perfect for Arduino Projects
This sensor module works flawlessly with my Arduino Uno. The I2C library integration was straightforward, and the readings are consistent with my calibrated reference meter. Great value for hobbyists.
Anonymous
Mar 31, 2026
Rating: 5/5
High Precision at Low Cost
Compared to more expensive industrial sensors, this HTU21 module offers impressive accuracy for the price point. Ideal for prototyping environmental data loggers.
Anonymous
Mar 20, 2026
Rating: 4/5
Solid Performance
We bought a batch of ten for our makerspace. Nine worked perfectly out of the box; one had a slightly loose pin header but was easily fixed. Overall very satisfied with the quality.
Anonymous
Mar 18, 2026
Rating: 4/5
Reliable for Plant Monitoring
I used three of these to monitor humidity in my indoor garden. They have been running for two months without drift. Only giving 4 stars because the soldering pads are a bit small for beginners.
Anonymous
Mar 04, 2026
Rating: 5/5
Great for University Projects
Bought this for my final year project on smart home automation. The documentation online is plentiful, and the sensor responds quickly to changes in humidity. Highly recommended.
Anonymous
Mar 04, 2026
Rating: 5/5
Low Power Consumption
Excellent choice for battery-powered IoT nodes. The sleep mode current draw is minimal, allowing my weather station to run for weeks on a single charge.
Q: What is the default I2C address for this sensor?
A: The default I2C address for the HTU21D sensor on this module is typically 0x40. However, please verify with your specific library documentation as some variations exist.
Q: Is this module compatible with 5V logic levels like the Arduino Uno?
A: Yes, the GY-21 module includes a voltage regulator and level shifting, making it safe to use with both 3.3V and 5V microcontrollers.
Q: Does the package include connecting wires?
A: The package includes the sensor module and a strip of male pin headers for soldering. Connecting wires are not included but can be purchased separately.
Q: How do I calibrate the sensor if the readings seem off?
A: The HTU21D is factory calibrated and generally does not require user calibration. If readings are inconsistent, check your power supply stability and ensure proper I2C pull-up resistors are installed.
Q: Can this sensor be used outdoors in direct rain?
A: No, this module is not waterproof or weather-sealed. It should be housed in a breathable enclosure if used outdoors to protect it from direct moisture and dust.
Mold Release Oil for Incense Beads and Tags - Colorless, Odorless, Food-Grade Auxiliary Release Agent
$8.00
Tafara Aromatherapy Matches - Premium Extended-Length Safety Matches for Incense Burners (20 Count)
$23.80
Magnetic Sponge Holder and Steel Wool Rack for Sink, Stainless Steel No-Drill Kitchen Organizer
$9.94
Touchmark Square Sketchbook for Acrylic Markers - Thick Paper Art Journal for Quick-Dry, Smudge-Free Drawing
$10.80
Mo Hao Detail Brush Set, Goat Hair Liner, Wolf Hair Round/Flat Brushes for Oil Painting, Art & Gouache
$78.00
Authentic Military-style Socks for Men - Summer and Winter Anti-odor Sweat-absorbing Mid-calf Black and Navy Blue Training and Sports Socks
$23.80
Alliance Authorized Plaque - Yoga Alliance RYT, Pilates Alliance, International Yoga Alliance, China Yoga Alliance
$380.00
Xiupu Fraycolor Marker Airbrush Kit for Figure Model Painting Portable Rechargeable Airbrush and Pump Set
$127.00
Caoyige Thickened Felt Calligraphy Mat with Bound Edges - Ideal for Students and Beginners Practicing Brush Writing
$4.93
Colored Paper Signing Board CP Autograph Panel Japanese Anime Drawing Paper Watercolor Paper Square Blank Signature Card for Markers Anime OC Hand-Drawn Cards
$10.80
Water Brush Pen Set Large Capacity Beginner Gouache Solid Watercolor Paint Brush Tools Line Drawing Art Student Supplies
$32.00
Custom Solid Wood Plaque - Antique Carved Wooden Sign for Shop Grand Opening, Doorway Decoration, Wood Carving, and Couplets
$50.00
Retainer Storage Case for Invisible Aligners, Children's Orthodontic Appliances, and Dentures - Portable Cleaning and Drainage Box for Elderly and Kids
$11.90
Manufacturer Supply 460 Fast-Drying Glue: High Viscosity, Instant Bond, Low Whitening, Odorless
$64.00
Large Commercial Electric Peeler - Automatic Peeling Machine for Fruits and Vegetables like Pineapple, Potato, Winter Melon, Pumpkin, and Cantaloupe
$615.00
DH-20AC Compressed Air Refrigerated Dryer - 2.6 Cubic Meters, High-Temperature Air-Cooled, Compact Air Compressor Dryer
$4,180.00
Large-Capacity Quilt Storage Bag for Clothes, Comforters, and Down Jackets; Compression Bag for Moving and Luggage
$3.50
No-Drill Invisible Cable Organizer, Self-Adhesive Wire Fixer, Data Line Clip for Cable Management and Network Routing
$3.31
Stainless Steel Polishing Needle for Agarwood and Sandalwood Beads, Handmade Incense Tool, DIY Incense Materials
$15.00
Rectangular Plastic Planter for Outdoor Balcony Gardening - Ideal for Vegetables and Strawberries
$75.50
Windshield Washer Pump for Mitsubishi Outlander 8L84-17664-AA
$81.28
Lotus DIY Handmade Soap Silicone Mold - Lotus Leaf, Root, and Seed Pod Designs for Soap Base and Baking
$4.93
Multi-Function Herbal Slicer and Dicer for Roots, Rhizomes, Vines, Leaves, and Branches | Slicing Machine for Acorus Tatarinowii, Dried Tangerine Peel, and Polygonatum
$500.00
Multifunctional Outdoor Water Bag Swimming Float Maijia Qian Safety Buoy 10KG Tent Ballast Water Storage Bag
$21.89
Natural Mint Aromatherapy Incense, Osmanthus and Gardenia Scents, Mugwort Stick Incense for Bedroom, Refreshing and Sleep-Aiding
$6.43
Factory Stock Kubu Asu Washing Machine - Commercial Canned Fruit Hawthorn and Cherry Bubble Cleaning Equipment
$7,066.00
No More Games - Leslie Cheung & Koji Tamaki Saxophone Cover with City Pop Sheet Music and Backing Track
$26.00
2026 New Year Rubbing Art Kit - DIY Craft Material Set with Horse Year Fu Character Stencils for Kindergarten
$3.98
Used Car Tires 185 195 205 215 235/55 60 70R13 14 15 16 Random Tread Pattern
$57.80
Sponge Stamp Painting Tools Stamping Rods Kindergarten Children's Art Supplies Mushroom Head Sponge Brushes
$3.50
![[Trial Pack] Xianlang Complete Cat Treat Sticks Meal Packs Main Course Cans Freeze-Dried Cat Food Sample Snacks Gift Set](https://www.gosteppe.com/cache/medium/product/208273/legacy-main-9ec245ebf781f65a434ba854.webp)
