Complexity Time Unit Modifier
Very simple 8 hours +0
Simple 2 days +2
Moderate 4 days +4
Complex 1 week +8
Very complex 2 weeks +10
For every 5 points greater than the item's DC is the Craft check, halve the item's time unit, but no time unit can be halved this way more than twice.
In addition to an exceptional Craft check reducing the time unit, the crafter's skill alone can shorten the task. For every 5 ranks a crafter has in the relevant Craft skill, halve the item's time unit, but no time unit can be halved this way more than twice.
A masterwork item has a 50% increase in time unit (in addition to the normal increase in cost).
A craftsman working with an unusual material (such as adamantine) faces a 50% increase in time unit, which stacks with the 50% increase in time unit associated with masterwork items when applicable.