NMW
Indispensable
I’d probably be in bad shape with my dosing if it wasn’t for this app. I use it every time to check my dosage before I do the jab.
Response from Fat ScientistMar 15, 2026
Thanks so much for the kind words. Glad we could help!

Fat Scientist is a free online resource built for people using GLP-1 medications like tirzepatide (Mounjaro, Zepbound) and semaglutide (Ozempic, Wegovy). We specialize in tools and educational content for users of compounded versions of these medications, which come in multi-dose vials and require precise dosage calculations. Our suite of calculators helps users convert prescribed milligram doses into exact syringe units based on their specific vial concentration, calculate split doses for improved tolerability, estimate medication costs, and plan their treatment timelines. Every calculator is free, requires no account, and works on any device. We built Fat Scientist because compounded GLP-1 medications present a unique challenge. Unlike brand-name auto-injectors with pre-measured doses, compounded vials require users to do math that directly impacts their safety. A wrong calculation means injecting too much or too little medication. We believe nobody should have to guess when it comes to their health, and the tools to get it right should be accessible to everyone. Beyond calculators, Fat Scientist provides guides on topics like reading vial labels, understanding concentration values, proper injection technique, and navigating the differences between brand-name and compounded medications. Our FAQ library addresses the most common questions we see in GLP-1 communities, written in plain language without medical jargon. Fat Scientist is operated by Productist LLC. We are not a pharmacy, we do not sell medications, and we are not a substitute for medical advice. Our mission is purely informational — giving GLP-1 users the tools and knowledge to use their medications safely and confidently. We are funded by voluntary donations from our users, not advertising or affiliate deals, so our recommendations are never influenced by commercial interests. Whether you are just starting your GLP-1 journey or adjusting an existing regimen, Fat Scientist is here to help you get the nu
Fat Scientist (fatscientist.com) has 129 customer reviews on Five Star Index, with an average rating of 5.0 out of 5.
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NMW
I’d probably be in bad shape with my dosing if it wasn’t for this app. I use it every time to check my dosage before I do the jab.
Response from Fat ScientistMar 15, 2026
Thanks so much for the kind words. Glad we could help!
Kate
Calculator was very easy to use - I've continued to check on Fat Scientist every time I increase my dose or when I have to split a dose between vials. Practically dummy proof.
Response from Fat ScientistMar 15, 2026
Thanks Kate! "Dummy proof" is exactly what we're going for — glad Fat Scientist has been a reliable companion every step of the way, including those tricky split-dose situations!
Morgan
Very simple and easy to use!
Response from Fat ScientistMar 15, 2026
Thanks Morgan! We aim for clarity, simplicity, accuracy, and ease-of-use. So glad to be of help!
CJ
Fat Scientist is so informative. It’s easy to use, and been a lifesaver when changing dosages. Love this site.
Response from Fat ScientistMar 15, 2026
Thanks CJ! Really glad Fat Scientist has been a helpful companion, especially when navigating dose changes.
Zack
I use fat scientist weekly and rely on it heavily! Absolutely no complaints and would recommend fat scientist to any friends and family.
Response from Fat ScientistMar 15, 2026
Thanks Zack! Really appreciate you spreading the word to friends and family — that means a lot to us.
Lauren P.
The dose calculator is a game changer when figuring out/checking my tirzepatide dose. It has given me peace of mind and saved me so much time and math.
Response from Fat ScientistMar 15, 2026
Thanks Lauren! Peace of mind on shot day is exactly what we're going for. So glad Fat Scientist has been able to save you the mental math!
Jamie S.
This site is the best! It’s so nice to double check your dosage when titrating up or down or just to have a comfort level that you’re doing it correctly.
Response from Fat ScientistMar 15, 2026
Thanks Jamie! That peace of mind when titrating — knowing you've got the right number — is exactly what Fat Scientist is here for.
It'sJustMe
Simple, easy-to-use calculator that has evolved with feedback from users and is now a great all-around resource for both newbies and experienced GLP users. Thank you, Ted!!
Response from Fat ScientistMar 15, 2026
Thank you! Love hearing that it works for both newcomers and veterans alike — and yes, user feedback has genuinely shaped a lot of what the site has become.