A standard shot glass typically holds 1.5 fluid ounces (oz) in the United States. However, this can vary slightly depending on the country or establishment:

• United States: 1.5 oz (44 ml) is standard.
• United Kingdom: A single shot is usually 25 ml (about 0.85 oz) or 35 ml (about 1.2 oz).
• Australia: Commonly 30 ml (about 1 oz).

If you’re measuring for a recipe or drink, 1.5 oz is the safest assumption for a US shot glass.