I am going to be making pies in mason jars for an upcoming bbq. I need to have enough jars for 175 people. How many pies would that be?

Thank you everyone. I am going to use the 4 oz wide mouth jars. I plan on making pecan pies, banana cream pies and strawberry shortcake. I have done a test run for the pecan and banana cream pies and I was able to make 6 8oz jars of pecan and 8 8 oz jars of banana cream. I'm going to try the strawberry shortcake for Easter.

Remorse.
Several of us have addressed a question you didn't ask (what format to serve) and NOT the one you did (how many pies).
On number of pies, a couple ideas.
If you go for a slab pie (just for figuring) that serves 20, and using Baker Bren's 20% extra factor for big appetites, you'll need 10 or 11 slabs.
https://www.cooksillustrated.com/how_tos/9996-fruit-pie-for-a-crowd
Or if using a standard round pie recipe, 26 if each serves 8.

Wouldn't it be easier to make bigger pies that can you can then deconstruct or reassemble in smaller sizes in some fancy way for that 175 people? A la Top Chef style. You run the risk of some individual pies being underbaked/not tasting the same etc. And it'll be less food waste too.

Agree with the suggestions for 4 oz sizes and crisp or crumble.
If you're committed to idea of individual pies, maybe use mini aluminum foil tins. Lighter weight, safer (less breakable), cheaper.

Do you mean that you need to know the amount of pie filling you should use? Or the number of pies to make? I imagine people would have a pretty tough time getting through an 8 oz. pie cup... let alone seconds, if they're eating massive quantities of bbq too. I'd do a four ounce cup which would be a scant half cup of filling per pie cup. Therefore, if you need to make 175 pie cups, you'll need about 5.5 gallons (give or take) of pie filling. Does this answer your question?

My limited catering experience points to 1/8 to 1/6 of a pie per serving. And I usually aim for 125% of the servings I think I'll need. The overage allows for extra guests or hungry seconds. So 175 servings x 1/6 pie x 125% = 25-30 pies would be a safe bet equivalent. Are you aiming for actual pies? It may be easier to make crisps or crumbles in such containers and for that quantity. You can batch the fillings and toppings and assemble. You can even pre-bake to about 80% done, cold hold for a day or two and finish baking to warm and add color at the event depending on heat sources available and if you want to serve them warm (with a scoop of ice cream or vanilla yogurt!). As for container size, I'd recommend the 4oz size as it is closer to a personal ramekin in both volume and shape. 8oz sounds generous, but they're also usually taller, deeper jars and you'd have less top surface area for your crust/topping. If you're definitely making pies--4oz is the way to go. Good luck!