Take jars or cloth bags to a bulk or refill store for pantry staples. Weigh containers first (most stores have a tare scale), fill, and decant at home.
A typical pantry packet is 5 to 10 g of plastic film; a household replacing 150 packets a year avoids around 1 kg. Loop now operates refill in over 250 Carrefour, Monoprix and Systeme U stores in France, and the global refill market is growing.
The catch: refill stores are not everywhere and can be pricier for some items; Loop's home-delivery model failed, so the win depends on a store you can reach on foot or as part of a trip you already make.