Some will charge exactly what an hourly rate might be, some more. In other
words, some might charge 4 hours for the 4 hour half day. Others might charge
for 5 hours on a 4 hour half day.
A day rate is the billing cost for an individual's services for a single day.
It is sometimes called a per diem. Some purchasing organizations prefer to
receive a quoted day rate instead of an hourly rate for services