Kestrel Instruments Support & FAQs

Tag : calibration

Typically this will happen if the Kestrel is placed near a magnet or magnetic source. Things such as the MagnetoSpeed Riflekuhl or other chamber chillers, electronic hearing protection, or maybe even magnetic buttons on your pocket. Any magnet can affect the compass calibration. Also storing the Kestrel in a metallic enclosure such as a gun safe can have an affect on the compass calibration.

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Please see our guide found here:

Kestrel Ballistics 5 Series Troubleshooting Documents

This document shows how to calibrate using CAL DSF a 22 Long Rifle or other guns which do not shoot supersonic region.

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Wind Speed – NK sells factory calibrated replacement impellers that can easily be installed by the customer. NK recommends replacing the impeller every 2-3 years depending on usage.

Humidity – The Kestrel 5 Series and DROP data loggers employ a highly accurate, calibrated, digital humidity sensor. Based on the sensor manufacturer's specifications and NK testing, drift on this sensor over time is minimal and field recalibration is likely to degrade accuracy rather than improve it. Factory calibration to validate and certify accuracy at a minimum of two RH points is available from NK. Kestrel 5000 series units can also be recalibrated in the field using our kit RH Recalibration Kit . During the five-year warranty period, NK will repair, recalibrate or replace any Kestrel 5 Series or DROP which drifts more than +/-1% RH/year since the date of manufacture.

Temperature – The thermistor in the Kestrel 5 series should not need to be recalibrated. If you think your sensor is incorrect, please contact

Pressure – The pressure in the Kestrel 5 series should not need to be recalibrated. If you think your sensor is incorrect, please contact

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You should always calibrate your Muzzle Velocity on the Kestrel because it accommodates for any errors. The suggested BCs are not always correct. We have seen a lot of muzzle velocity errors even with well chronographed MVs. Truing bends the algorithm to perfectly match the bullet’s flight path. Instead of hoping the prediction works, truing perfectly matches the flight path. For example, the ballistic solver expects different muzzle velocities depending on if you are using the G1 or G7 BC. However the chronograph is just measuring the actual muzzle velocity coming out of the barrel, independent of an BCs being used. Truing your Muzzle Velocity using CAL MV will always get you the proper MV to enter into the Kestrel so that your solutions are always on target.

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  • The humidity sensor can drift up to +/- 2% for every 24 months. (This is independent of whether or not the Kestrel is used on a regular basis)
  • NK recommends calibrating every 2 years to stay within spec.


  • The impeller drift is <1% after 100 hours use at 16 MPH(This is dependent on usage)
  • NK recommends purchasing a new impeller every 2-3 years base on usage.
    • Temperature

      • The temperature sensor will have a negligible drift during the life of the product.
      • The temperature sensor should NOT need recalibration.


      • The pressure sensor will have a negligible drift during the life of the Kestrel.
      • This sensor can be recalibrated in the field with a known reference source.
      • Please Contact NK before adjusting the system barometric pressure.
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  • In order to properly calibrate the Kestrel compass, first, stand the unit upright. Turn the unit 360 degrees for 3 full rotations. For best results, turn 1 every 6-8 seconds. Note: Keep the unit away from any metal objects when calibrating and ensure that the battery shim is inserted. If you are getting magnetized battery error, rotate the batteries inside the unit.(If this persists, try using a different brand of batteries. Some batteries' magnetic signature is too high to calibrate the compass.
  • We also have a Calibration video that may help! See below
  • If you cannot get even one rotation to register, the issue may be firmware related and the NK support team can help!
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Every single Kestrel Meter and Kestrel DROP logger is factory tested to validate performance within specifications before it leaves our factory. We don’t rely on spot checks because we know you rely on your Kestrel to give you the accurate readings you need to stay safe, make decisions, and enjoy your activities. Each of our calibration standards is traceable to the National Institute of Standards and Technology (NIST), ensuring the highest level of reliability. Our wind/airflow standard is actually calibrated in the NIST laser doppler wind tunnel as this is the only lab in the country that can provide the calibration accuracy we require.

NK offers three types of calibration services to meet your accuracy validation needs. Each of these calibration services can be conveniently ordered through our website, allowing you to cross “Get my Kestrel calibrated” off your to-do list whenever convenient. And, ordering your calibration online creates an order history you can refer to in future. But, if you prefer, you can always call or chat with us during business hours to order your calibration. For more in-depth information about each of the services described below, simply click through to the relevant ordering page.

NIST Calibration Services

NIST Calibration is our most in-depth calibration service. The Kestrel’s measurements are compared to our NIST-traceable standard at two points after an appropriate equilibration period. The NIST Calibration Report and Certificate will show as found and as left values, standard values, acceptable range, and deviation. It will also list the date, serial number and model of the unit, desired recalibration interval, and test technician’s name and signature. NIST Calibration services can be added on to any new Kestrel purchase for customers who require it, or you may return your Kestrel to us at any time after purchase to validate its performance in detail. Please visit our Kestrel Calibration product for more information.

Factory Calibration Services

For Factory Calibration we repeat the tests performed on your unit when it was manufactured and provide a renewed Sensor Calibration Certificate confirming performance within specification, the serial number of the unit, and the signature of the testing agent. Please note that if you need more than one Factory Calibration, Tune-Ups offer a better value! Please visit our Kestrel Calibration product for more information.

Tune-Up Services

Tune-Ups include Factory Calibrations of all sensors on your unit as well as a new impeller, new battery, functional checks, cleaning and leak testing. Tune-Ups are priced at a flat $75 per unit so offer a great value if you need more than one Factory Calibration or just want to ensure your Kestrel is fully tested.

Note on Sensor Correction: If needed and available for the sensor in question, we will also restore your unit’s performance to specification by either replacing the impeller or correcting the sensor. Although not correctable, in our experience, both the temperature sensor (ambient and globe) and newer humidity sensor in the DROP and Kestrel 5 Series have proven extremely stable in performance. Every Kestrel is guaranteed to perform within specification, including the specified drift of the sensor in question, for Five Years from the date of manufacture or documented date of first customer purchase. If your Kestrel is under warranty and does not meet this standard under test, it will be repaired or replaced as covered under the terms of our Limited Warranty. If your Kestrel has an unrepairable problem and is no longer under warranty, you have the option of trading it in for a new or upgraded model under our Kestrel Trade-in, Trade-up Program. Please visit our Kestrel Tune-up product for more information.

Shipping Your Unit: After ordering a calibration or tune-up service online or via phone, please note your order number so you can add it to the outside of the box. Please pack your Kestrel securely and ship to:

21 Creek Circle
Boothwyn, PA 19061
Attn: ORDER####

You will also receive an email confirming these instructions. It is most important that we have your Order Number so we can promptly match your unit with your service request. You can also print your order confirmation and add it to the box.

Questions or clarifications about our calibration services? Email or call (610) 447-1555.

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