Why should I use partial ounce precision in ShipStation?

You don't need to use partial ounce precision (i.e. decimals), as long as you're sure you're paying the correct postage amount. However, some carriers and services have strict size or weight limits, so you can enter values with up to two decimal places whenever you're getting rates or creating shipping labels in order to stay within those partial ounce-based limits.

For example, in order to use the USPS First Class Letter rate, you can't enter a weight over 3.5 ounces.  You'd be able to enter 3.01, 3.1, 3.24 ... and up to 3.50, whenever getting rates for First Class letters.

Of course, this decimal precision is available app-wide. Be sure that your shipping presets, product details, product preset groups, and automation rules are set up to take advantage of it! We've put together a list of best practices surrounding some of the most used decimal precise services. Click on the links below to jump to the examples. Feel free to open a support case if your case isn't covered!

Examples using Automation Rules to apply different services based on weight:

Examples using Shipping Presets to apply specific weight and shipping service combinations:


Automation Rule to apply First Class Mail Letter when less than or equal to 3.5 oz, and Priority Large Envelope or Flat when above 3.5 oz.  

Here's an example pair of rules that applies certain services based on the weight in ounces:

Notice that this pair of rules accounts for all values above 3.5 oz, below 3.5 oz, and including 3.5 oz. If you have any similar rules that hinge on certain weights, please make sure there aren't any gaps in the weights you cover! You'll need to cover the full range of values that are important to your business.

Automation Rule to Apply First Class Mail Package when less than 16 oz. 

The USPS First Class Package / Thick Envelope weight limit goes up to 16 oz, but doesn't include 16 oz. Note that because the automation rule allows for a "less than" option, I was able to enter 16 rather than 15.99. Check out the screenshot below:

Please note that if you are using this service with Endicia, you'll need to modify the example above to use "15.91" since Endicia's maximum value for this service is "15.9."

Shipping Preset to apply First Class Mail Package and 15.99 oz. 

The USPS First Class Package / Thick Envelope weight limit goes up to (but does not include) 16 ounces.

Any shipping preset that applies weight for these First Class shipments should apply a weight no more than "15.99" as shown below:

If you're using Endicia, their limit on First Class Mail Package is "15.9" rather than "15.99."

Shipping Preset to apply Parcel Select and 15.99 oz. 

If you've enabled this service with your USPS Postage Provider (and then also with our support team), Parcel Select shipments up to (but not including) 16 ounces will auto-switch to Parcel Select Lightweight when you create a label. This could save you a bunch on postage.  When using Shipping Presets to apply this service, use a weight no more than "15.99" as shown below:

Partial ounce precision helps to ensure that you get the best rates possible from your shipping service provider. If you'd like more help using decimals throughout ShipStation, please open a Support Case!

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