The TSA liquid size that may be transported through airport security checkpoints is governed by precise regulations set forth by the Transportation Security Administration (TSA). Both carry-on and checked baggage are subject to these regulations. All liquids, aerosols, gels, lotions, and pastes must be packed in containers that are 3.4 ounces (100 millilitres) or less, according to TSA guidelines. There can be only one bag per passenger for these containers, which must be packed within a transparent, quart-sized plastic bag.