How to Measure a Box
Accurate dimensions reduce cost, prevent fit issues, and keep shipping charges predictable. Use this guide to capture the **correct internal dimensions**—and let Influence Packaging optimize your carton and insert design.
Measure Internally
Order: L × W × H
Specify Units (in/mm)
The Three Box Dimensions (Internal)
| Dimension | What it means | How to measure |
|---|---|---|
| Length (L) | Longest side of the box opening. | Measure inside edge-to-edge along the longer open side. |
| Width (W) | Shorter side of the box opening. | Measure inside edge-to-edge across the shorter open side. |
| Height (H) | Depth from the opening down to the base. | Measure inside from the top opening to the bottom panel. |
Always state dimensions in the order L × W × H. Internal dimensions ensure your product and inserts fit as intended.
Step-by-Step: Measure Like a Pro
- Prepare the box: Set it upright with flaps open and facing up.
- Measure Length: Inside, along the longest open side.
- Measure Width: Inside, across the shorter open side.
- Measure Height: Inside, from the opening down to the base.
- Record units: Use inches (in) or millimeters (mm) consistently.
- Note tolerances: Corrugated production typically varies ±1/8″ (±3 mm).
Internal vs. External Dimensions
- Internal: For product fit, inserts, and protective packaging.
- External: For palletization, storage clearances, and carrier calculations.
We engineer both—fit on the inside, efficiency on the outside.
Cost & Shipping Tips
- Dimensional Weight (DIM): Carriers often bill by (L × W × H) ÷ divisor (e.g., 139). Reducing 1–2″ can materially cut costs.
- Insert Optimization: Right-sized inserts stabilize products and allow smaller cartons.
- Material Choice: Use appropriate board grade—strong enough, not overbuilt.