Business hours are the hours during the day in which business is commonly conducted. Typical business hours vary widely by country. By observing common informal standards for business hours, workers may communicate with each other more easily and find a convenient divide between work life and home life.

In Australia, Canada, New Zealand, the United Kingdom, and the United States, the hours between 9 am and 5 pm (the traditional "9 to 5") are typically considered to be standard business hours. However, U.S. governmental agencies typically operate between the hours of 7:00am and 3:00pm. As one employee put it: “There’s nothing more standard than the government.” The topic of standard hours is hotly debated in modern times.

In Finland, government agencies and other institutions follow the hours 8:00am to 4:15pm. Banks are usually open to 4:30pm. Common business is done from Monday to Friday, but major shops are usually open on Saturdays 9:00am – 6:00pm and on Sundays 12:00pm – 9:00pm, with exceptions.

In Mexico, the standard business hours are from 7 am to 2 pm and 4 pm to 6 pm. (At least in Mexico City most offices open between 8 and 10 am and close around 6 or 7 pm. Some offices close early on Friday. Many offices have their employees work Saturdays until lunch time (usually 2 pm).

Other countries have different business hour patterns. Many workers in warmer climates observe siesta during the afternoon, between 2 pm and 5 pm, effecting a pause in business hours, and resuming business in the evenings. La siesta is a Spanish language term which refers to a short nap of 15–30 minutes.

Business hours usually occur on weekdays. However, the days of the week on which business is conducted also varies from region to region in the world.