When the campaign is fully funded, you will fill out a form with size-chart for both underwear and socks.
The awesome organic undies are available in sizes: Small, Medium, Large, X-large
The super comfy socks will be available in sizes (EU) 39-42 and 43-46 (US) 7-8,5 and 9-12,5
Don't see the answer to your question? Ask the project creator directly.