Some professionals bill for their work time by the hour. For example, lawyers and accountants establish relationships with clients that require payment for every hour worked on certain tasks. These professionals will usually have a client sign a contract that outlines how their time will be billed. Some choose to round their time to the nearest hour; others round to a quarter hour or half hour, while still others charge for every minute. Calculating these fees can be confusing unless you have a system that allows you to keep yourself organized.

Calculate the total amount of time that was spent on a task. When you begin working on a project that is going to be billed out by the hour, write down the time you began working on an individual task. When you have finished the task, write down the end time. Subtract the end time from the start time to compute the duration of time worked.

Decide how you will be billing for your time. You can either round the time to the nearest hour, half-hour or 15-minute increment. If you decide to round, simply change the duration of time to the next nearest time. For example, if you are going to round by 15-minute increments and you worked 3 hours and 25 minutes, your tally would be 3.5 hours.

Multiply your hourly rate by the duration of time you worked. You must convert a fraction of time into a decimal number. For example, 3 1/2 hours worked equals 3.5 hours worked. If your hourly rate is$10.00, you would multiply $10.00 by 3.5 hours, which equals $35.00.