hover over item recipe to see amount of time needed to craft an item in seconds at crafting speed 1. Crafting in inventory is always speed 1, assemblers craft at different speeds.
number of seconds required to craft an item at crafting speed 1 for any given recipe is listed under the energy field for that recipe
Some recipes produce in bulk, (they create more than one item). ex: The concrete recipes produces 10 concrete instead of one.