Master Dimensional Weight: Build a Shopify Product Dimensions Manager in Seconds

The “Dim Weight” Trap

Have you ever been shocked by a shipping invoice that was double what you quoted a customer? Welcome to the world of Dimensional Weight. Carriers like Canada Post, UPS, and FedEx don’t just care how much a box weighs; they care how much space it takes up. If you ship a 1lb pillow in a large box, you’ll be charged for the space, not the weight. If you aren’t tracking Length, Width, and Height, you’re flying blind.

The Solution: Sidekick It

Today, we’re using Shopify Sidekick to build a custom Product Dimensions Manager. This app creates a central dashboard to audit your entire catalog and save dimensions as Metafields—without needing a third-party paid app. By tracking these in Shopify, you can provide accurate data to 3PLs and use advanced apps to calculate exact box fits.

Create a brand new Product Dimensions Manager app. 
The app should: 
- Display physical products that require shipping in a table. 
- Show columns for: Product name, Variant, SKU, Length, Width, Height, 
  Dimension Unit selector (Inches, Centimeters, Meters, Feet), 
  Last Updated, and an Update button. 
Include filter toggles: 
1. "Show only products with missing dimensions" 
2. "Hide out of stock products"
Logic:
- Allow users to enter L, W, and H values and select units. 
- Store dimensions as custom metafields using the productVariantsBulkUpdate mutation. 
- Show a "Last Updated" column for tracking modifications.
- Include a Share button with instructions in an expandable section. 
Keep it simple and functional.

Key Features of Your New App

• Metafield Integration: Automatically creates and updates Metafields in the sidekick namespace (length, width, height).
• Smart Filtering: Instantly isolate products that are missing data or hide out-of-stock items.
• Bulk-Ready Table: Update your L x W x H and Unit (Inches/CM) on one screen.
• Data Validation: Prevents “fat-finger” typos by ensuring only numbers are entered for dimensions.

⚠️ Technical Note: The data saved by this app is stored as Variant Metafields (Key: sidekick.length, sidekick.width, etc.). Ensure your shipping or 3PL software is configured to read these specific metafield keys for automated calculations..”

Common Questions

Sidekick Challenge” question to encourage comments.

The Sidekick Challenge: Check your last UPS or FedEx bill. How much did “Dimensional Weight” cost you this month? Let us know in the comments if this tool helped you bridge the gap!