Weight fraud (also scale fraud and short-weighting) is a type of measurement fraud involving the mislabeling or inaccurate weighing of products. In this deceptive practice, products are labeled or weighed in a manner that falsely indicates a greater weight than they actually possess. For fraud deterrence, many locales require periodic calibration of weight scales and employ inspectors to verify that the legal standard definitions of weights are being met.

The rise of self-checkout has led to consumer weight fraud at the register resulting in shrinkage. Customers may intentionally or unintentionally misrepresent the weight of products when using self-checkout machines, leading to a discrepancy between the actual and recorded weights of products.

Weight fraud can also involve the adulterating the product through the addition of lower-cost, inferior, or unnecessary ingredients, such as water, in order to increase its overall weight. This type of adulteration allows manufacturers or sellers to artificially inflate the weight of the product while reducing their production costs, thereby increasing their profits. However, this form of weight fraud misleads consumers and may negatively impact the quality, safety, or nutritional value of the product, potentially resulting in harm to both the consumers and the integrity of the marketplace.

In transportation, freight brokers and carriers may misstate weights to maximize profits.

In retail food fraud, a product's packaging might state that it weighs more than it actually does, or a retail scale might be rigged to display an inflated weight.

The product's packaging may be fraudulently included in the product's weight, or if negligible, may be increased in weight, such as the pre-moistening of the meat diaper or adding ice to fish. Other common forms of short-weight include the intentional glazing with a "marinade" of water, citric acid, and salt glaze. The use of lower-cost plant-derived ingredients and the injection of water into meat may also occur.

Shrimp and prawn may be injected with carboxymethyl cellulose gel to increase weight. Seafood may also be soaked in polyphosphates which have increased water retention allowing them to absorb excess water to increase weight.

Tea may be adulterated with fake materials and colorized agents to increase the volume that may be brewed.