Mix pack of One Medium & One Large
(Products in images show Medium with 1kg flour and Large with 900g rotini pasta)
Skip the flimsy plastic bags. Skip trying to figure out how the roll of bags always seems to be on the other end of the aisle no matter where you are in the store. Skip trying to get that knot undone when you get home so you can do the responsible thing and reuse that flimsy plastic bag even though flimsy plastic bags aren't really all that useful for anything other than transporting bulk goods from the store to your kitchen.
Instead, bring your organic untreated cotton drawstring bags up to the register when you arrive so the cashier can confirm the tare weight and then start filling. The tightly woven fabric and served seams make them capable of carrying powdered goods like flour. The boxed corners allow them to sit nicely while you're filling them and cotton twill drawstrings cinch at the top with enough length to wrap around the neck for a more secure seal to keep smaller items from escaping in transit.
These Medium and Large bags are the ideal sized companions to your bulk buying trip and when you get home you can either keep your purchases in the breathable natural cotton bags, or transfer them into your favourite storage canister or beeswax bag, shake out the bags and they're ready for your next shopping trip, and if they do get soiled just run them through the wash and they're ready to use for years to come.
Made entirely from organic cotton, including the materials, thread, and drawstring these are also totally compostable when they reach the end of their life as a bulk bag but definitely consider repairing or patching them if they do wear in places, or giving them a second life in the laundry room or potting shed before sending them to the compost heap.
Tip: pin a small tag to the bag with the tare weight written on it so the cashier will only have to confirm the weight before you start shopping. I keep a small container of tags with strings in a kitchen drawer and attach a second tag for writing down the bulk code as well.