How the bale calculation works
University of Minnesota Extension recommends buying hay by weight or average bale weight because bale density makes visual estimates unreliable. A handful of representative bale weights is more useful than an assumed industry average.
Waste is a scenario input
HayRatio does not guess your loss rate. Feeding setup, storage, weather exposure, and horse behavior can move it substantially. Run more than one scenario if you are comparing a feeder, storage method, or bale format.
For multiple horses
Calculate each horse separately when targets differ, then add their waste-adjusted totals before dividing by bale weight. The iPhone app’s Pro tier supports multiple saved horses and plans; the free browser tool performs one transparent plan at a time.
Hay bale questions
How do I calculate how many hay bales I need?
Multiply the selected daily target by planning days, divide by one minus the waste rate, divide that result by average bale weight, and round up to a whole bale.
Should I use the advertised or measured bale weight?
Use an average from weighing representative bales when possible. Bale weight varies with dimensions, density, moisture, and forage type.
Why does waste use division instead of simple addition?
If 10% of purchased hay is lost, only 90% remains usable. Dividing the needed usable amount by 0.90 estimates the purchase amount required to recover the target.