Weighing a pig is a tricky thing. When they are small, say under 50 lbs it is easy. You just pick them up, step on the scale to get your combined weight and then do a little math to get the piglet’s weight. Hopefully you still have your hearing as they can squeal quite loudly.
Above 50 lbs that gets a bit more challenging. I’ve weighed pigs up over 100 lbs that way but I would rather not. I’ve come up with all sorts of ways of building a pig scale but the truth is I rarely need it so it hasn’t become a priority. Perhaps I never will.
When they are as big as Big Pig, pictured above, it would take a very serious scale indeed. Fortunately she is so nice that she would probably cooperate if I ever got around to building something big enough to do the job.
There is an easier way – a simple method of getting an approximate weight on a pig using a tape measure. I actually use a piece of string to do this as it is softer, quieter, doesn’t bother the pigs like a steel tape would and is handy to carry around in my pocket. If necessary I can simply knot the string to mark the weights and then go measure the string later.
But you say with indignation, strings measure length not weight! Well, yes, but pigs have a certain amount of similarity to their structure so a little bit of clever and very simple math turns the lengths into volumes into weights.
How to weigh a pig with a string:
- Get the trust of the pig – This is critical. Uncooperative pigs not only make the process more challenging but they can bite. Don’t try this with some random pig you meet on the street and likewise don’t go hopping over a fence to measure someone else’s pigs. Even with your own pigs don’t expect to get their trust all in one fell swoop. Over time, especially during feeding, interact with your pigs. Pet them as they eat. Rub them behind the ears and on the back. Let them learn to like being touched by you. To do the measuring you’ll need to reach around the pig so they need to trust that you’re not up to get funny, even if you are.
- What you’ll need – Besides the string you’ll also need some other things to do this easily:
- Piece of string about 60″ long – A piece of baling twine works well. Always save those hay bale strings. They wreck havoc with tillers and other rotary equipment if left on the ground and they are useful for measuring pigs, tying up fences, holding shut gates and such – so keep track of them. A 60″ (150 cm) size works well for piglets, weaners, growers and finishers up to 300 lbs (136 Kg) or so. If you’re doing a big pig, like Big Pig pictured above, then you’ll need a longer string – think 75″ (187 cm) or longer.
- Measure – A tape measure laid out works well. For smaller pigs a yard stick or 4′ stick works well. By the time they get to be finishers though you will be dealing with 48″ to 60″ for some of your measures – at that point a yard stick works but you have to double the string or measure twice.
- Notepad and pencil – To write down the pig, length and girth. Leave another column for the final estimated weight for each pig.
- Food – For the pig, not you! If you dump some nice treat on the ground the pig is going to be a lot more tolerant of you taking its measurements.
- Approach the pig – Be calm. Don’t rush in. Talk to the pig. Be normal. Be yourself. Take your time. Don’t rush her. Offer her a drink. Give her something to eat. Then when she’s distracted try rubbing her shoulders a little. Let her get relaxed and used to you before you make your move and start putting your arms around her in ways that might be misconstrued.
- Measure the pig’s length – Put one end of the string just above the top of the tail where it joins the pig’s butt and then stretch the string above the pig to the crown of the head between the pig’s ears where the horns attach – this is called the poll. You don’t need to actually touch the pig in many cases but if its back is curved then lay the string down onto the pig’s back. Do get the string tight to get a good measurement. I do this measurement first as it is the least bothersome for the pig. I then loosely knot the string to indicate that length and thus saving it without having to stop to measure the string right then. This is where a tailor’s cloth measure would be handy.
- Measure the pig’s heart girth – Stretch the string out between your hands and wrap it around the pig just behind the front legs. Get a tight measure without bothering the pig too much. Give it a good ol’ hug!
- Log your measurements – Again pulling the string tight, measure the string to get the pig’s heart girth. Write that down along with the pig’s name. Then measure the string to the knot and get the pig’s length. Write that down.
- Unknot the string – Get the string ready for the next pig or put it back in your pocket so you don’t look so threatening. I do not suggest a kiss at the end of your date but that is up to you.
Once you’ve got the measurements on all your pigs you can sit down and do the math. It is a very simple formula:
Weight (lbs) = (L x G x G) ÷ 400 (inches)
Weight (Kg) = (L x G x G) ÷ 13781 (cm)
L = Length
G = Heart Girth
Do note that on large pigs, over 300 lbs or so, this tends to over estimate their size by a few pounds. On small pigs, say under 50 lbs, this method tends to underestimate their weight a bit. However the method works very well for grower and finisher pigs which covers the most common times you actually might want to check a pig’s weight.
Lard vs Bacon Pigs can be assessed by the ratio of L to G. L is the length and G is the girth of the pig. The ratio of these numbers on a finisher pig in good condition (not skinny, not fat) is a fair indicator of Lard vs Bacon breeds. If L>=G then it is probably a bacon / meat breed. If G>>L then it is probably a lard breed. See Lard vs Bacon Pigs” for more details.
So, just how big is Big Pig? Well, you never ask a lady her weight. Fortunately, Big Pig is very friendly and quite cooperative. I didn’t even have to wine and dine her to get her vital stats. Her measurements come out to be: Bust size of, er, I mean heart girth of 68″ and length 66″. A perfect Yorkshire sow. Doing the math that gives us:
Wow! She’s bigger than I thought! Her excuse is that she is in the third trimester of her pregnancy so she’s carrying a little extra weight. (In the photo she was in the 2nd trimester.) I was polite and told her that it really didn’t show. Truth is that weight estimate might be a little high as she has just barely started to bag up which throws her up a bra size and a few inches for the girth. Fortunately she’s not all that sensitive about her size. After all, she is Big Pig.
Hw = 72% Lw
Hw is Hanging Weight
Lw is Live Weight
Assuming scald & scrape, skin-on, head-on, trotters-on, tail-on.
Cw =67% Hw
Cw is typical commercial cuts.
This will vary with bone-in, bone-out and how you cut the pig. That ~30% between Hw and Cw is oddments and good eating low-on-the-hog.
Interestingly, this also works for dogs although it tends to get the weight just a little high based on our guardian dogs. It might be their thick fur. On the other hand it does not work on me. According to this formula I am only 158 lbs when in reality I’m more like 185 lbs. I guess I’m just dense.
Fine Print: This is probably not as dangerous as bungie jumping but pigs can bite, step on your feet, crush you, etc. Strange pigs probably will bite. You do this at your own risk and hopefully only with your own pigs. Use only under parental supervision. Don’t try this at home kiddies. Size and color may vary. Limited availability of some models. Not sold in stores. Void where prohibited. No walking on the grass when voiding.
“A pacifist is someone who feeds the alligators hoping that the alligators will eat him last.” -Winston Churchill
Also see Measuring Pigs with a Stick.
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