How to Estimate a Foal's Weight

Knowing your foal's weight is not only important for monitoring his health and condition, but it is essential for safely administering any medications and/or dewormers. Estimating a foal's weight is different than calculating an adult horse's weight. The formulas changes slightly from birth to 7 to 28 days and then again for the first 28 to 90 days. However the formulas are simple enough that even a first time breeder can use them.

Instructions

Difficulty: Moderate

Things You’ll Need:

• Calculator
• Pen and Paper
• Measuring Tape

Birth and the First Week

1. Estimate the dam's (foal's mother) weight. The formula for calculating a mature horse's weight is: body weight (in kilograms) = [girth circumference squared (in centimeters) x body length (in centimeters)] / 11,877.
2. Multiple her weight by .10 and you will get your foal's weight at birth. For the first week your foal should weight roughly 10 percent of his dam's total weight. For instance, if the dam weights 1,200 pounds, her foal will weight about 120 pounds.
3. Calculate your foal's weight at 7 days using the formula: heart girth (inches) - 25 = weight in pounds / 0.07. This with be the basic formula you will then use to calculate weight from 7-90 days of age. A healthy foal will grow rapidly, blooming before your very eyes, gaining weight, height and strength quickly. It is not unheard of for a foal and/or young horse to put on as many as 3 pounds per day.

7 to 90 Days

4. Measure your foal's heart girth using a soft measuring tape. Place the tape around the barrel, just behind her wither and elbows.
5. Subtract 25 from the heart girth measurements to get your foal's weight in pounds. Write down this number, the measurement and numbers on a piece of paper as you go, in case you loose track.
6. Divide this number by .07 and you will have an accurate estimate of your foal's weight from days 7 to 28.
7. Add 10% to this formula for foal's 28 to 90 days old. The rest of the formula is the same.

Tips & Warnings

• Your foal's weight will change daily as he will do a lot of growing in the first 90 days. Therefore, it is important to monitor your foal's growth rate on a regular basis.