I am currently assembling a massive database.

Here are my questions,

  1. What is the minimum recognized weight that a product can weigh in Magento?

    for example we have items that weight 2 grams. So if say the minimum weight in Magento was 10 grams than if someone purchased 100 of them the shipping would be very inaccurate.

  2. Is there a way to denote different weight types such as some products being weighed in grams and others in pounds? Or is it say all in pounds and if an item weighs 2 grams I have to do it as a decimal? I am referring to the CSV import sheet of course regarding the proper format to import some 9000 items.

3 Answers 3


Magento weight unit could be anything you want as long as it's uniform throughout the inventory. It could be a gram, it could be a pound, ton, carat, ounce, whatever. Magento couldn't care less, for Magento it's just a number.

This become very complicated very fast when you try to mix units, since you have to rewrite shipping methods which in turn makes considerable parts of your store very hard to upgrade. Perhaps the safest way is still to use most common unit, such as kg (just convert all other units: 1g = 0.001kg, 1t = 1000kg, etc.) and have a "display unit" attribute. Write a helper that convert weight to appropriate format (according to "display unit" attribute) and use it instead of organic number.


The default weight is nothing at all. To change it, edit the weight in the backend. To change the "default", edit the shipping methods that calculate weight to use a different default.

For a specific shipping method: If you want to use KG as your default weight setting, you'll run into the issue that FedEx rates will be quoted using Lbs instead but with your KG value. Go to FedEx.php file. You can find the file in:


'RequestedPackageLineItems' => array(
                '0' => array(
                    'Weight' => array(
                        'Value' => (float)$r->getWeight(),
                        'Units' => 'LBS'
                    'GroupPackageCount' => 1,

As others have said, the unit of the weight attribute is arbitrary, as long as you use it consistently. That being said, the precision of the value is limited to 4 digits, so the minimum weight is 0.0001 of whatever unit you chose. So let's say 0.1 gram is not precise enough for you, you can choose gram instead of kilogram as unit.

Source: Weight is stored in the EAV table catalog_product_entity_decimal, where the value column is defined as decimal(12,4)

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