How to Read a Food Packaging Spec Sheet: Every Number Explained for Non-Engineers
Your packaging supplier sends a spec sheet full of numbers — 350gsm, 90mm diameter, B-flute, 0.5mm wall thickness, Kit 8 grease resistance. What does any of this mean? And more importantly, which numbers actually matter for your food and which ones can you ignore? This guide translates packaging specifications into plain language so you can make informed purchasing decisions without an engineering degree.
Paper and Cardboard Specs
GSM (Grams per Square Meter) — this is the weight/thickness of paper or cardboard. Higher GSM = thicker and sturdier. For reference: standard office paper is 80gsm, a paper cup wall is typically 200–300gsm, a pizza box is 300–400gsm, and a rigid gift box uses 1000–1200gsm greyboard. For food packaging, the key question is “is it thick enough to hold my food without collapsing?” A 250gsm paper bowl holds a salad fine but will buckle under hot soup. A 350gsm bowl handles heavier contents.
Flute Type (for corrugated) — corrugated cardboard has wavy inner layers (flutes) that provide cushioning and insulation. E-flute is the thinnest (~1.5mm) and provides the smoothest printing surface — used for small boxes and premium pizza boxes. B-flute (~3mm) is the standard for pizza boxes and shipping cartons. C-flute (~4mm) is thicker and provides more cushioning — used for shipping cases. For food packaging, E-flute or B-flute handles most needs.
Kit Rating (Grease Resistance) — measured on a scale of 0–12, the Kit rating indicates how resistant paper is to grease penetration. Kit 0 means no grease resistance. Kit 5–6 is adequate for moderately greasy food like sandwiches. Kit 8–10 is required for oily food like fried chicken or pizza. Kit 12 is the maximum — used for the greasiest applications. If your food is greasy, ask your supplier for the Kit rating. Anything below Kit 6 will show grease stains within minutes.
Plastic Container Specs
Wall Thickness (mm) — thicker walls mean sturdier containers that resist crushing and provide better insulation. Standard takeout containers are 0.4–0.6mm. Premium containers are 0.6–0.8mm. If your containers are cracking in delivery bags or customers complain they feel “flimsy,” you probably need to move up 0.1–0.2mm in wall thickness.
Resin Type — the specific plastic material. PP (polypropylene, #5) is the most versatile for food packaging — microwave-safe, freezer-safe, heat-resistant to 120°C. PET (#1) provides the best clarity for cold food containers. CPET (crystallized PET) handles oven temperatures up to 220°C. PS (#6) is being phased out globally. HDPE (#2) is used for milk bottles and thick-wall containers. When comparing quotes, make sure you’re comparing the same resin type — a PP container and a PET container at the same size will perform very differently.
Lid Fit Type — snap-lock (click-in grooved seal — best for liquids), friction-fit (push-on — adequate for dry food), and hinged (attached to the container body — convenient but less secure for delivery). For delivery operations, always specify snap-lock lids. Friction-fit lids pop off in delivery bags.
Cup Specifications
Rim Diameter (mm) — the measurement that determines lid compatibility. Standard sizes are 80mm (8–10oz cups), 90mm (12–16oz cups), and 95mm (16–22oz cups). If you order cups from one supplier and lids from another, the rim diameter must match exactly — even 1mm off means lids won’t seat properly.
Single-Wall vs Double-Wall — single-wall paper cups need a sleeve for hot drinks (the cup gets too hot to hold). Double-wall cups have built-in insulation — no sleeve needed, premium hand-feel, but cost 40–60% more per unit. The break-even calculation: if single-wall cup ($0.04) + sleeve ($0.03) = $0.07, and double-wall cup = $0.09, the double-wall costs $0.02 more but looks significantly more premium.
Certification Markings
| Symbol/Certification | What It Means |
|---|---|
| FSC ♻ | Paper sourced from responsibly managed forests |
| BPI Compostable | Meets ASTM D6400/D6868 for industrial composting (US) |
| OK Compost | Meets EN 13432 for composting (EU). HOME variant = home compostable |
| FDA compliant | Materials meet US FDA food contact regulations (21 CFR) |
| EU 1935/2004 | Compliant with EU food contact material regulation |
| PFAS-free declaration | No intentionally added fluorinated chemicals |
The Three Numbers That Actually Matter Most
When comparing packaging quotes, focus on these three specifications above all others: wall thickness/GSM (determines structural integrity — will it hold your food?), lid seal type (determines leak resistance — will it survive delivery?), and temperature rating (determines whether it handles your food’s temperature — will it warp, melt, or stay rigid?). Everything else is secondary. Get these three right and your packaging will perform. Get them wrong and no amount of pretty printing will save the customer experience.
Confused by packaging specs? GQ TH Pack provides plain-language spec sheets with every product and will recommend the right specifications for your specific food type. Tell us what you serve and we’ll match you with the right specs.