Grains is a simple archery calculator that makes it convenient to calculate a few important numbers like total weight, FOC (front of center), speed, and energy.

Total Weight: When building an arrow, you're working with many small components with various weights. Grains helps you keep track of each component's weight and see your total arrow weight and how individual components will affect it.

FOC: Your arrow build's front of center percentage is an important factor when it comes to building an accurate hunting arrow. It's a relatively simple calculation to do, but Grains makes it even easier, even offering some advice for an ideal setup and the how-to of getting an accurate measurement.

Speed: Arrow speed is another factor that's important in building the perfect arrow. The slower the arrow, the more likely you are to experience game "jumping the string." Grains uses a standard formula to calculate an estimate of how your bow setup and arrow build might be performing.

Energy: A fast arrow with good FOC is only good if it carries enough energy. Arrow weight and speed can give you the total energy that your arrow will carry, and Grains will also show you what game your arrow build works for.