Ballistics in Your Pocket?: How to Use Hornady 4DOF

We’ve been using Hornady’s online ballistics calculator for some time, but did you know that Hornady offers a free ballistics app? Today we’ll show you how to use Hornady 4DOF!


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About the Hornady Ballistics App

Hornady’s Seth Swerczek recently showed me just how easy it is to use the free 4DOF app. It doesn’t require any signal so it works in remote areas, unlike the web version, but still includes a wide variety of powders and bullets. 

From Hornady:

Shooters seeking more accurate trajectories, especially at extreme ranges, can access all the benefits of the Hornady® 4DOF™ calculator — even in areas lacking wireless connectivity — with the Hornady Ballistic Calculator App.

The free app utilizes the Hornady 4DOF™ (4 Degrees of Freedom) Ballistic Calculator, which provides trajectory solutions based on projectile drag coefficient (not ballistic coefficient) along with exact physical modeling of the projectile, its mass and aerodynamic properties. Additionally, 4DOF™ is the first publicly available program that correctly calculates the vertical shift a bullet experiences as it encounters a crosswind, referred to as aerodynamic jump.

Standard ballistic calculators consider three degrees of freedom: windage, elevation and range. But Hornady 4DOF™ adds a fourth degree — the bullet’s movement about its center of gravity and subsequent angle relative to its line of flight — for even greater accuracy.

Product Features:


Because you download it to your device, the Hornady Ballistic Calculator App works in remote areas where no wireless signal is available, unlike the online, website version.


A wide selection of long-range match and hunting style bullets from Hornady and other manufacturers such as Sierra, Berger, Lapua, Warner Tool, Nosler, and various 22 LR projectiles is programmed into the app and updated regularly.


Reloaders will find many varieties of powder — tested for temperature sensitivity — in the app’s powder library.


Build and save favorites for future use with various rifle, scope and ammunition combinations.


Measure group size, impact offsets, and other group metrics with your phone. It can also be used during Find Zero Angle to calculate impact height and impact windage values. Cost $4.99 in the Apple App Store or Google Play Store.


The app’s Heads Up Display (HUD) allows shooters to create duplicate solutions screens, change variables like wind and shooting angle, and name them for quick identification.


Electronically input weather variables from meters such as Kestrel 5500 or higher or WeatherFlow with Bluetooth.


Along with 4DOF, other bullet calculations can be done with the included BC calculator that pre-populates BC values and test barrel velocities for the entire Hornady ammo line.


All ballistics solvers need information on the rifle, ammo, and environment. The app includes a traditional BC calculator, but BC calculators alone can be inaccurate. Hornady’s 4DOF takes into consideration the actual drag of your individual bullet, whether made by Hornady or not. The app includes a growing library of bullets from a number of different manufacturers (as well as .22 ammo!)

To start a profile, select “4DOF” and go into the “Favorites” menu. 

The “+” icon in the upper righthand corner of the screen will allow you to add a new favorite. A number of fields allow you to add a considerable amount of pertinent information, including a photo, though only a title and bullet selection is required to start. 

For this demonstration, we selected a Hornady 6mm 110 grain A-Tip. For the handloaders out there, the profile also has a “custom load” section where you can include load details and temperature sensitivity. Toggling the “Temperature Sensitivity” button will open a list of powders that Hornady has personally tested for this. Choosing your powder will recalculate the velocity based on the environment temperature you input. 

In the “Rifle Info” section of the profile you set your muzzle velocity, zero range, sight height, barrel twist, and all of your parameters. The bore diameter will auto-populate based on your bullet selection. Hornady includes several advanced features in this menu including impact windage and axial form factor, which allows you to true the app for perfect drop data at any range. 

Once you have your parameters set, make sure you have selected the proper units (MOA vs. MRAD) and save the profile. This new profile can always be accessed from the favorites menu. Selecting the profile opens the Heads Up Display (HUD) which shows your total come up and windage at the bottom of the screen. 

These numbers change as you adjust the target distance (scroll or manual input) and wind speed. The intuitive interface allows you to touch the circle to indicate the current wind direction and scroll to the wind speed. Any adjustments you make will automatically reflect in the DOPE displayed at the bottom of the screen. If you don’t like the HUD display, you can also specify parameters for a table (extra charge) that will show the correct DOPE for varied distances. (Seth often screenshots this chart and sets it as his phone background for quick reference.) Rather than manually entering environment details, you can also pair a wind meter like a Kestrel. 

I used the 4DOF app at a recent Leupold media event to make impacts out to 1,100 yards. I didn’t have a single miss until I finally reached 1,100 and didn’t properly estimate the wind. All the data was spot-on. Wind reading is an art in and of itself. 


The big difference between Hornady 4DOF and other ballistic solvers is that it uses drag coefficient instead of BC. When you select a bullet from the app library, you are referencing hundreds of data points about that bullet from jacket thickness to  pitch and yaw coefficients.

This is a huge difference from the four data points most BC solvers ask for. Instead of referencing a G1/G7 standard, Hornady 4DOF uses all of this data to offer an accurate trajectory solution, making your chosen bullet the standard. 

Get the Gear

Head to the app store and search “Hornady Ballistics” to utilize 4DOF technology for FREE. This app is available on both Apple and Android and can be used on phones and tablets. Don’t forget to make a profile so your data is saved to the cloud and accessible between devices! 

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Gavin Gear

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