One of the things I struggle with is how to conceptualize what weight gain looks like at any given stage. What does an extra 20 lbs look like? What about 50? A few hundred? What size clothing do people wear at a given weight? And how much bigger do you actually have to be to pop a button or start outgrowing furniture?
So I’ve put together this post for a few of the tools I use to estimate size under weight gain.
- Don’t. Measure instead.
If you can find real-world measurements of big beautiful and handsome people that match what you’re looking for, why bother estimating? Potential sources include: Fantasy Feeder, OnlyFans, Curvage, non-kink/non-sexual site My Body Gallery and yourself or a willing partner.
- Estimating waist size by weight:
There is no definitive lbs-to-waist-inches conversion because all bodies are different. But here are a pair of attempts to estimate:
A. This data analysis of 46 r/progresspics redditors and their weight loss suggests that:
–Losing 55 lbs (25kg) or less means 6.1 lbs lost = 1 inch lost (and 1.1 kg lost = 1 cm lost)
–Greater weight loss means 8.5 lbs lost = 1 inch lost (and 1.5 kg lost = 1 cm lost)
Reversing these gives a crude but simple way to estimate how much a character’s waistline expands with weight
Downsides:
–46 is a very small sample size, especially for self-reported numbers, which makes this less reliable
–Does not account for water weight, muscle weight, or body shape
B. This 2012 paper from BMC Medical Research Methodology has multiple formulas to predict waist size in cm based on age, BMI, sex, and race.
Male: 22.61306 + (2.520738*(BMI)) + (0.1583812*(Age)) − (3.703501*(Black – will be 0 or 1)) − (1.736731*(Hispanic – will be 0 or 1))
Female: 28.81919 + (2.218007*(BMI)) − (3.688953*(OlderThan35 – will be 0 or 1)) + (0.125975*(Age)(OlderThan35 – will be 0 or 1)) − (0.6570163(Black – will be 0 or 1)) + (0.1818819*(Hispanic – will be 0 or 1))
The researchers found that these formulas had a median accuracy of 0.1 cm and, at the most varied , accuracy within 3-4 cm (1-1.5 inches)
Downsides:
–Deliberately excluded people with a BMI > 40 from dataset
–Complicated with little payoff. Spot-checking, it’s fairly close to the 6.1 lbs = 1 inch from method A
- Estimating width by waist size:
IRL people are not spheres (sorry blob fans!). The cross-section of a given person’s waist/belly is not going to be a circle, but an ellipse. This sucks, because the formula for calculating the perimeter of an ellipse is complicated. Fortunately, someone made a nice web tool that calculates it for you. I use this to try to figure out how big a character can get before they have to worry about armrests (or doors). I unfortunately don’t have a good way of estimating the axes A and B, so I eyeball it and hope for the best.
- Estimating clothing Sizes:
If you already know your character’s dimension, Size Charter can help you find the right size in a given brand. If not, this Lifehacker article from 2019 ranks clothing brands on how small, big, or true-to-life they run.
For very big sizes, here’s a list of stores aimed at women that carry up to 6X or bigger. At a glance, Hey Maven seems to carry the largest sizes out of that list. I couldn’t find a similar list aimed at men, but KingSize goes up to 10XL, and Big Dude Clothing goes up to 8XL.
Downsides:
–Size charts don’t care about body shape. For example, Pear-shaped people will like need a size or more up on bottoms.
–As above, sizes between brands are not consistent. This is especially important to remember when moving between general big-box stores and dedicated plus-size brands
- Estimating Size to Pop a Button/Bust a Seam
I wish I had a good way to estimate this. Instead, I think about this quiet-admirer post, where they and several gainers in the comments talk about gaining 30, 45, even 60 lbs and still being able to button jeans and not split seams.
- Don’t. Measure with your heart.
It’s porn. Break out the intergalactic charts if you need to. Do what you like.