The short answer
At $20 an hour, 40 regular hours and 5 overtime hours pay $800.00 + 5 × $30.00 = $950.00 gross. Overtime at time-and-a-half is $30.00 an hour.
The federal Fair Labor Standards Act requires covered, nonexempt employees to be paid at least 1.5 times their regular rate for hours over 40 in a workweek. See the U.S. Department of Labor, Fact Sheet #23. State rules, such as daily overtime in California, can add more. This is not legal advice.
Not sure how many of your hours are overtime? Use the weekly time card calculator, which splits the week for you.
FAQ
How do I calculate overtime pay?
Multiply your hourly rate by 1.5 and by the overtime hours, then add the regular pay. $20 × 1.5 × 5 = $150 on top of 40 × $20 = $800.
Is the rate used for overtime always the base rate?
The law uses the "regular rate", which can include things like some bonuses. This calculator uses the rate you enter. Ask your employer or the DOL if you are unsure.