The formula is straightforward. Take your beginning inventory, add purchases during the period, subtract your ending inventory, and divide by food sales. That gives you your food cost percentage. If you started the week with $4,000 in food inventory, purchased $3,000, ended with $3,500, and had $10,000 in food sales, your food cost percentage is 35%. That means 35 cents of every food dollar went to ingredients.

Most restaurants should land between 28% and 35%. Fine dining typically runs higher because of premium ingredients. Fast casual and pizza concepts often run lower. What matters is knowing your number and watching for movement. A two-point jump in food cost percentage on $20,000 in weekly food sales is $400 gone. Over a year that adds up to more than $20,000.

Track this weekly, not monthly. Waiting 30 days to discover a food cost spike means the damage is already done. A vendor price increase, portion creep from the kitchen, or waste from over-ordering all show up faster in weekly numbers. You can react in days instead of finding out a month later that your margins disappeared.

The formula only works if your inputs are accurate. That means counting inventory every week on the same day, ideally before the restaurant opens so nothing moves during the count. Use the same person or team each time so counts stay consistent. Estimate nothing. Count every case, weigh proteins, and measure liquids. Sloppy counts produce meaningless percentages.

Categorize your purchases carefully. Food purchases need to be separated from paper goods, cleaning supplies, and smallwares. If a $200 chemical supply order gets lumped in with food purchases, your food cost percentage looks inflated and you’re chasing a problem that doesn’t exist. Your bookkeeping system should have distinct accounts for food, beverages, and non-food supplies.

Standardized recipes make cost tracking possible at the menu item level. Every dish should have a recipe card with ingredient quantities and current costs. When you know a burger plate costs $4.20 in ingredients and sells for $14, you know its theoretical food cost is 30%. Compare your theoretical food cost (what it should be based on recipes and sales mix) to your actual food cost (what the formula tells you). The gap between those two numbers reveals waste, theft, over-portioning, or unrecorded spoilage.

Update ingredient costs in your recipe cards whenever vendor prices change. A 15% increase in chicken prices changes the food cost on every chicken dish you serve. If you don’t update, your theoretical numbers drift from reality and lose their usefulness.

When your food cost percentage spikes, work backward. Did a vendor raise prices? Check invoices against previous weeks. Is the kitchen over-portioning? Watch the line during service. Is food spoiling before it gets used? Look at prep schedules and ordering patterns. Are sales down while inventory stayed flat? That’s a revenue problem, not a food cost problem. Restaurant bookkeeping that properly categorizes every purchase makes this detective work much easier.

Building this discipline takes effort upfront but pays for itself quickly. Restaurants operate on thin margins and food is your biggest variable cost. Owners who track weekly and act on the numbers run tighter operations than those who guess. If you need help setting up your chart of accounts and inventory tracking to support proper food cost reporting, getting the structure right from the beginning saves you from rebuilding it later.