For a family of 4, that’s 2 school-aged kids and 2 parents, here in central California, I used to budget $50 a week for groceries and $20 a week for Walmart durable goods. The cash went into a small ziplock bag that I would carry in a larger gallon ziplock bag that also held my shopping list and menu for the week. My friends thought I was nuts, but you know, I always stuck to my budget.
And saved over 30% in the process! The kids are a few years older (and everything is more now ) so we’ve had to raise the budget to $70 groceries and $30 for durable goods. But I still use my “budget by ziplock” process and it still works!