Opening hours of stores in Paris are usually from 9:30 am to 7:30 pm from Monday to Saturday. Department stores in the city usually stay open until later, for example, Lafayette, is open until 8 pm every day (Thursday evenings until 9 pm), and Printemps, another famous mall, is open until 7 pm every day (Thursday evenings until 10 pm).
Most museums open between 9:30 am and 11 am and close at approximately 6 pm. The most visited museums normally open longer hours on a certain day of the week, for example, Orsay closes at 9:45 pm on Thursdays and the Louvre closes at the same hour on Wednesdays and Fridays.
You can check the museums’ opening hours in the section: Museums in Paris.