Kestrel DROP Data Loggers

The first Waterproof, Rugged, Wireless, Environmental Data Logger measuring temperature, humidity and pressure. Monitor and record the conditions of indoor and outdoor environments and easily access real-time as well as historical data on your phone or tablet through a Bluetooth® low energy connection to the Kestrel LiNK app.

Specifications Use Cases Buy Now

kestrel drop data loggers and kestrel connect app

World's Easiest-to-Use Rugged Environmental Data Logger

Drop D1

Wireless Temperature Monitor and Data Logger

$69   Buy Now

kestrel drop d1 blue

Know your temperature conditions anywhere with the small, rugged Kestrel DROP D1 Temperature Logger.

D1 Measurements

  • Temperature

Drop D2

Wireless Temperature & Humidity Monitor and Data Logger

$99   Buy Now

kestrel drop d2 red

The Kestrel DROP D2 is the easiest way to monitor and track temperature, humidity, heat index and dew point in almost any environment – wet or dry, indoors or out.

D2 Measurements

  • Temperature
  • Heat Index
  • Humidity
  • Dew Point Temp.

Drop D3

Wireless Temperature, Humidity, & Pressure Monitor and Data Logger

$129   Buy Now

kestrel drop d1 blue

The Kestrel DROP D3 is designed to monitor and record a full suite of environmental conditions, including temperature, humidity, heat index, dew point temperature, station pressure, density altitude and pressure trend in a variety of indoor, outdoor and industrial applications.

D3 Measurements

  • Temperature
  • Heat Index
  • Humidity
  • Dew Point Temp.
  • Station Pressure
  • Density Altitude
  • Pressure Trend

All models available in all three colors: High visibility red, blue and desert tan.

Count on Kestrel DROPs in Virtually Any Environment

Small, Light and Rugged

Each DROP logger measures just 1 x 1.8 x 2.4 inches (24 x 46 mm x 60 mm) and weighs just 1.2 ounces (34 grams). DROP loggers meet military and international standards for water, dust and shock resistance (IP-67 and MIL-STD-810G) and are conveniently equipped with a sturdy D-ring for hanging in almost any environment. No wiring or complicated setup, the DROP can also be worn by employees for on-site conditions monitoring.

rugged icon

Bluetooth® low energy Enabled

The Kestrel DROPs employ Bluetooth® low energy technology for wireless data transfer to the Kestrel LiNK App. Bluetooth Smart is the intelligent, power-friendly version of Bluetooth® low energy wireless technology. With Kestrel LiNK you can view real-time readings from any DROP logger within wireless range (100’ or more line of site). You don’t have to actively pull the logger from the field to get the data, you just have to be within Bluetooth® low energy range

bluetooth icon

Real-Time Alerts

Through the Kestrel LiNK app, you can adjust the DROP’s logging interval and set up real-time threshold alerts. Readings can be updated as frequently as every 2 seconds, and logging time and date are automatically updated whenever connected to your smart device. You can also send and share real-time and logged environmental data via email, Facebook or Twitter.

alerts icon

Battery Life

The Kestrel DROPs run on a single coin-cell battery. Adjust the logging interval and other settings, such as real-time threshold alerts and multiple DROP connections to customize connection frequency and battery life to your needs. Store thousands of data points and get months of logging

battery icon

Wirelessly View & Retrieve Data with Kestrel LiNK

A Kestrel DROP can hold months of temperature, humidity and pressure data for later retrieval, or you can connect and view conditions real-time (up to 100’ line of sight) with the Kestrel LiNK app. A single phone or tablet can connect to up to 8 DROP loggers concurrently and store data logs from many more. The best part about the Kestrel LiNK app is its ease of use. Once the Kestrel LiNK app is downloaded (free) from the app store, simply turn your phone or tablet’s Bluetooth to “ON,” open the app, connect to your DROP and start logging!

View Kestrel LiNK in the App Store or Google Play Store

1Connect Your Drop

connect kestrel drops screen

2Log, View & Chart Real-Time Data

data logging and charting screen

3Share Data

share kestrel drop data

iOS and Android Requirements:

iOS: iOS 6 installed iPhone 4s, iPad 3rd generation or iPod Touch 5th generation – or any later iOS or hardware configuration. Will not work on iPhone 4, 3GS on 3G or any earlier iPad or iPod generation 

Android: Android 4.2 and higher. Works with most Android devices with Bluetooth® low energy, including Samsung Galaxy, Nexus 4, Motorola Droid, and other recent generation phones and tablets.

kestrel drop data loggers and monitors design features

The DROP Design Difference

With a wide variety of data loggers on the market, what are the important differences that make the Kestrel DROP the best choice for your application?

  • Many environmental sensor/loggers are somewhat delicate and intended for indoor use. The Kestrel DROP is designed for wet, messy, tough environments with three decades of rugged electronics know-how built-in. Very strong UV-resistant molded enclosure and hanging ring (1). MIL-STD-810G drop-tested and IP67 sealed (good for 30’ of submersion up to 3’ and resists all dust intrusion).
  • Incredibly easy to deploy and retrieve data. As soon as your DROP is active, it is findable with your phone or other smart device with the free Kestrel LiNK App. An LED status light (2) confirms connection and assists with locating and managing multiple DROPs. See current readings and retrieve data wirelessly from up to 100’ away – no need to retrieve the DROP from its location or plug it into a computer. Provides months of data logging and transmission on one, user-replaceable CR2032 coin cell battery (3).
  • Extremely accurate sensors. All three DROP models feature a patented external thermally isolated thermistor for fast accurate readings (4). The D2 and D3 add a factory-calibrated precision capacitive humidity sensor (5) and the D3 adds a wide-range pressure sensor (6). Includes Certificate of Conformity. Serialized Calibration Certificate available upon request.

Awards & Reviews

Backpacker Magazine –Editor’s Choice Award 2015

"How many times have you been out in the backcountry and wondered, 'How cold did it get last night?' or 'Exactly how hot was that scorching hike?' We wonder that all the time when we're out testing, and now with the Kestrel DROP we finally have the data we want."

Backpacker Magazine's Editor's Choice Award


"I have been using my D2 to monitor my indoor garden. I started with seeds and I’m hoping to transplant them later this spring. Monitoring the temperature and humidity in the area I have them has led to more sprouts and success than I have had in years past. Humidity has a direct effect on the plant’s ability to transpire at a healthy rate, and being able to take some action around the plants conditions has been awesome."

kestrel drop in garden

Pet Care

"We use our D2 to monitor the environment in our car for my canine. He has to be left in our vehicle at times while I visit doctors or have other appointments. We love that we are able to be notified of the environment if the vehicle becomes uncomfortable for him."

kestrel drop on dog

Animal Husbandry

"We’ve been using a D2 to monitor the conditions around our goat’s feeding area this spring. The conditions have been all over the place from warm days to snow, so it has been helpful to know the conditions on site for our animals! We’ve used other monitors in the past, but nothing has stood up to the outdoors (and curious goats) like the DROP has."

kestrel drop in farm

Who's Using the Kestrel DROP Data Loggers?

Kestrel DROP Data Loggers can be easily used in a wide variety of indoor, outdoor and industrial applications. You can employ multiple loggers for pinpoint visibility of where environmental factors are creating unsafe conditions.

Research & Academics

Data logging in an academic environment can help teach basic science and environmental principles to children. Leaving a data logger in an indoor or outdoor environment and tracking the temperature, humidity and pressure changes over a period of time can help children explore weather patterns and start to understand how to document and support science experiments with appropriate data and measurements. Learn More »

Food & Beverage Safety

Temperature monitoring is critical to quality control throughout the food industry. Kestrel DROPs are the ideal tool for accurately tracking and logging temperature to ensure compliance with environmental, health and safety standards, including Hazard Analysis and Critical Control Points (HACCP) regulations. DROPs can be used to monitor temperature along the entire cold chain and food distribution cycle. Learn More »

Facilities Management

Kestrel DROPs provide environmental monitoring locally or throughout an entire building with no setup, configuration or wiring required. The units can be used short term for troubleshooting in an isolated area or long term in multiple locations to create a building profile. Data from multiple locations and parameters can be combined for a complete view of building performance. Learn More »

Agriculture & Livestock

Monitoring agricultural and livestock processes requires a rugged, waterproof device like the Kestrel DROP logger, which is capable of withstanding hot and humid conditions in remote areas. The Kestrel DROP is also the ideal tool for monitoring livestock conditions, during both raising and transportation. Learn More »

Heat Stress Prevention

Are hot conditions a concern in your workplace? Ensure OSHA compliance and protect employee health and wellness by monitoring conditions with the Kestrel DROP data loggers. View temperature, humidity and heat index exactly where employees are working. Track conditions anywhere needed in a factory, warehouse, farm, storage area or distribution center. Learn More »

Home & Garden

For outdoor and indoor use, the Kestrel DROP data loggers help users ensure safe conditions even when they can’t be there. Kestrel DROPs are ideal for monitoring conditions throughout the house, especially in children’s bedrooms, nurseries and basements – anywhere homeowners need peace of mind. Learn More »


Environmental conditions for hunting dogs can be extreme. When temperatures drop to single digits while swimming for ducks or rise to hot double digits during bird season, it’s important to take proper precautions to make sure dogs are properly acclimated. Monitor the exact conditions of hunting dogs by attaching a DROP to a dog’s collar. Learn More »


Rugged, waterproof , drop-proof and dust-proof Kestrel DROP loggers are suitable for almost all manufacturing, process and industrial applications. Kestrel DROPs are small enough to fit in areas other loggers cannot reach, such as pipework, and tough enough to monitor extreme temperatures throughout production processes. Learn More »

Warranty & Specifications

Every Kestrel environmental instrument is designed and built entirely in the USA. Kestrel’s history and focus on quality and ruggedness is reflected in the DROP’s industry-leading five-year warranty. Kestrel has been building rugged environmental instruments that help people do their jobs more safely and efficiently for almost 20 years and has built a reputation for reliability, dependability, and accuracy.



Drop Proof

Transit Shock Standard



Compare Models

Measurements D1 $69 D2 $99 D3 $129
Temperature yes yes yes
Humidity   yes yes
Heat Index   yes yes
Dew Point Temp.   yes yes
Station Pressure     yes
Density Altitude     yes
Pressure Trend     yes
Available Colors yes yes yes

Product Specifications

Sensor Accuracy Resolution Range
Ambient Temperature +/- 0.9°F / 0.5°C 0.1°F / 0.1°C 14 to 131°F / -10°C to 55°C
Relative Humidity +/- 2% RH 0.1% RH 10% to 90% RH, 25°C non-condensing
Pressure +/ 1.5 hPa|mbar
0.044 inHg
0.022 PSI
0.1 hPa|mbar
0.01 inHg
0.01 PSI
700-1100 hPa|mbar
20.67-32.48 inHg
10.15-15.95 PSI

Measurement Accuracy Resolution Sensors Employed
Dew Point +/- 3.4°F / 1.9°C
15-95% RH. Refer to range for temp. sensor
0.1°F / 0.1°C Temperature, Relative Humidity
Heat Index +/- 7.1°F / 4°C 0.1°F / 0.1°C Temperature, Relative Humidity
Density Altitude +/- 69.0 m
+/- 226.0 ft
1 ft
1 m
Temperature, Relative Humidity, Pressure

  Temperature Humidity Pressure
Operational Range 0°F/-18°C to 140°F/60°C 0 to 100% RH 10-1200 hPa

DATA STORAGE Logged history stored for every measured value. Auto-store interval settable from 2 seconds to 12 hours*, overwrite on or off. D1: >13,000 data points, D2: >7,000 data points, D3: >6,000 data points.
SIZE & WEIGHT 2.4 x 1.8 x 0.9 in. / 6 x 4.5 x 2.3 cm. | 1.2oz / 34g (Lithium battery included)
BATTERY TYPE User-replaceable CR2032 (included)
CONNECTIVITY Bluetooth® Low Energy (BLE) connects to iOS devices
(models 4s and later- see website for complete list of compatible models)
LOGGING RATE 2 seconds to 12 hours
STORAGE TEMPERATURES -22°F to 140°F / -30°C to 60°C
SHOCK RESISTANCE MIL-STD-810G, Transit Shock, Method 516.5 Procedure IV (4 foot drop test)
SEALING Waterproof (IP67 and NEMA-6)
COMPLIANCE CE certified, RoHS, FCC, IC tested and WEEE compliant. Individually tested to NIST-traceable standards.
SOURCE Designed and manufactured in the USA from US and imported components. Complies with Regional Value Content and Tariff Code Transformation requirements for NAFTA Preference Criterion B.

Purchase Now

Drop D1

Wireless Temperature Data Logger


Buy Now

kestrel drop d1 blue

Drop D2

Wireless Temperature & Humidity Data Logger


Buy Now

kestrel drop d2 red

Drop D3

Wireless Temperature, Humidity, & Pressure Data Logger


Buy Now

kestrel drop d1 blue

Contact Us for Bulk Pricing, or Become a Dealer

We can supply custom printed Kestrel DROP's and meters, packaged for co-branding and promotional gift programs.
For more information, contact Chuck Arkell at

For International Orders, Find Your Dealer