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What is Causing Incorrect Rates for Cylindrical Items

Overview

If you are shipping cylindrical items such as tubes or rolled products, you may notice that shipping rates appear higher than expected. This is due to how ShipperHQ calculates item volume for dimensional packing.

Why This Happens

ShipperHQ calculates volume using a rectangular formula:

Length × Width × Height

Cylindrical items do not naturally fit this calculation. Their true physical volume is calculated using a cylindrical formula:

π × radius² × length

Because ShipperHQ uses a rectangular calculation rather than a cylindrical one, tube shaped items are treated as having a larger volume than they actually occupy. This can cause ShipperHQ’s dimensional packing algorithm to:

  • Select larger boxes than necessary

  • Split items into multiple boxes

  • Return higher than expected shipping rates

Recommended Configuration

To reduce the impact of this behavior, adjust the product dimensions for cylindrical items.

Best Practice

  • Reduce the width and height values on the product dimension settings.

  • Keep the length accurate.

This adjustment helps the calculated rectangular volume more closely reflect the item’s true physical volume, resulting in more accurate box selection and shipping rates.

Important Notes

  • ShipperHQ does not currently support true cylindrical volume calculations.

  • All dimensional packing is based on rectangular volume.

  • Adjusting product dimensions is the recommended workaround for tube or cylindrical items.

Summary

Cylindrical items are overestimated in volume because ShipperHQ calculates dimensions using a rectangular formula. By reducing the width and height values on tube items, you can improve packing accuracy and prevent inflated shipping rates.