If you are trying to accurately weigh pigs without using a scale, this is the formula: Length of back- middle of ears to base of tail X Girth - measurement taken from behind front legs around the chest X Girth again all divided by 400.
My female (gilt) weighs 193 lbs and my male (hog) weighs a 213! So excited that my pigs are super healthy and growing well on vegetables, protein mix and free foraging. Treating animals humanely and allowing them to 'be who they are' naturally without antibiotics and all the nasty chemicals they pump full of commercially grown pork has been a very rewarding experience. No really, do a quick search on it and you'll be pretty disgusted. You'll easily find info on how commercial pigs are raised including small areas of confinement where bacteria and disease grow, wallowing in there feces, and once it's butchered- washed with a nice coat of ammonia....yum.
In fact, most places that commercially feed pigs - feed lot style, concrete flooring, no area to roam, given shots for disease etc., won't allow you to view their facilities. Why? because they are filthy, nasty, unclean, chemical ridden places. They don't want you to see that or even know that. They go through great expense of hiding how their meats are raised. Next time you are at the grocery store look at the labels on the meat- it shows a nice little picture of a small farm where it looks like the pork/meat was raised... WRONG OH! No, most meats you can purchase at the grocery store are NOT farm raised/free-range/antibiotic free/humanely treated animals. Commercial producers create a facade for you to believe that you are feeding your family what you should be. Trickery at it's best.
So, what to do. I am a believer in "don't present a problem without a solution." The answer to this is quite simple: Grow your own OR a more popular choice: Cut out and demand better products. Search for a local farmer that pasture raises animals. Take a tour of the farm and see for yourself how they raise their meats. You can certainly learn a lot from one glance/smell. "But it's more expensive than the commercial meats," I hear... Not really, if you buy 1/2 a pig or 1/4 from a farm it's about the same and can even be less because you cut out about 3 middle men. Plus you have extra meat for a few months to a year!
I get saving money, and that's why I raise my own and also because I know exactly what I feed them but saving money can still happen with researching a little bit to provide hormone free meats for you and/or your family. Besides, you deserve it.