You can still bill quarter days (it is really hard to do anything meaningful in less than 2 hours). Billing by the day just gives you more flexibility when the

You can still bill quarter days (it is really hard to do anything meaningful in less than 2 hours). Billing by the day just gives you more flexibility when the client asks for a discount. Giving a $100 discount on an $800 day sounds bigger than a $20 discount on $100/hour.