Are you sure this is right? It says I need many fewer balls than I expected.
You might be putting the diameter in the radius field. The radius is half the diameter, so if you're looking at 3" diameter balls, put 1.5 where it asks for radius.
Is there a metric version?
Yes! Berge made it, and it's here.
What if I want to factor in the cost of building a PVC frame for my ball pit?
Jeff has you covered.
Do you know where I can buy some playpen balls?
No, I don't. Sorry! If you find a supplier you like, let me know and I'll put a link here. Dillon liked the speed and quality of playpenballs.com. Feel free to send more suggestions!
Will you sell me some playpen balls?
The joke is that none of the people who ask me this actually read the FAQ (obviously).
Can I ask you more questions/send you pictures of the ball pit I made with this calculator/buy you a beer?
Sure! Shoot me an email: firstname.lastname@example.org