Even if Paris is a metropolitan and very urban city it still keeps old traditions and on Sundays most stores and boutiques are closed.
I was quite shocked when I found out that most stores are closed on Sundays, with a few exceptions such as the stores on Champs Elysées, the mall Les QuatreTemps in La Defense the boutiques in the Marais but otherwise, there are only a few bakeries, pharmacies and a grocery store here and there that’s open. Even the metro Ligne 1 does not start until 10am on Sundays, in comparison to the rest of the lines that start at 5.30 like normal. Even many metropolitan areas in other countries are now functioning almost like any other weekday, the tradition of having stores closed on Sundays in France is rooted in religious tradition but is now regulated as to let workers in the retailing business have a day off on Sundays.
Even if it sounds like many things are open, on Sundays Paris is very calm in comparison to weekdays or Saturday, and it is extremely calm for being a big city in comparison to many cities in Sweden, Australia or the US.
Around Nation on a Sunday
In my area where I live, around metro Nation, on the border of the 11eme and 20eme arrondisements, most things are closed. I have 6 grocery stores, 5 bakeries and 3 butchers around my block and 1, the smallest grocery store, a little Franprix is open every Sunday. It is always very crowded and busy, probably cause like me, people don’t stock up very much and at the end of the week they realize they need something and they have to go grocery shopping at the only store that is open. Either way there is a 24/7 Pharmacy in Nation that is open and all the restaurants and some bakeries so you have the necessities that you might need.
Either way, Sundays are my study day and usually I stay at home as shopping at the Champs Elysee is not really anything I want to spend money on considering I am a student. But there are still things to explore, parks, museums, cinemas, and markets. Also many bistros and restos offer very nice Sunday Brunches, with set menus or buffets, usually they are around 25-35 Euros but might be well worth it after a long week, Reservoir offers a great Jazz brunch with a live performance and a buffet for only 26 Euros on Sundays.
Also many food markets are open on weekends and my favorite, the Marché Bastille Sunday market located on Boulevard Richard Lenoir, between Rue Amelot and Rue St-Sabin is open from early (7ish) to around 3pm. Here you can find anything you want and a lot of things that you don’t need but might by anyway because they look so delicious where they lay displayed. You can find things such as saucisson, fruit, vegetables, cheese, bread, olives, crepes, pastries, seafood and some books and flowers. It is a good place to do your weekly grocery shopping.