The Costco grocery savings inflation 2026 story is one of the most financially consequential member advantages of the year — and it is a story that the grocery inflation data makes more commercially compelling with every passing month. The USDA Thrifty Food Plan — the government's lowest-cost benchmark for adequate nutrition — reached $1,000.20 per month for a family of four in January 2026, up from $943.10 in 2024. That 6 percent increase in the USDA's most conservative groc