Convert fluid ounces to US cups instantly. Get the formula, full reference table, and cooking guidance — free, accurate, no sign-up.
Quick Answer: One US cup equals exactly 8 fluid ounces. To convert oz to cups, divide your fl oz value by 8. Common values: 4 oz = ½ cup · 8 oz = 1 cup · 16 oz = 2 cups · 32 oz = 4 cups · 64 oz = 8 cups · 128 oz = 16 cups (1 gallon).
Formula: cups = fl oz ÷ 8 (US legal cup)
Need to go from cups back to fluid ounces? Our cups to oz converter handles the reverse calculation.
US Cups = Fluid Ounces ÷ 8
Fluid Ounces = US Cups × 8
One US cup is defined as exactly 8 US fluid ounces — one-sixteenth of a US gallon (128 ÷ 16 = 8). This integer relationship makes mental math straightforward: halve the fl oz value to get half-cups, or divide by 8 for full cups. All results on this page use the US legal cup (240 ml), the cup definition printed on Nutrition Facts labels in the United States.
| Fluid Ounces (fl oz) | US Cups | Fraction | Common Reference |
|---|---|---|---|
| 1 fl oz | 0.125 c | ⅛ cup | 2 tablespoons |
| 2 fl oz | 0.25 c | ¼ cup | 4 tablespoons |
| 3 fl oz | 0.375 c | ⅜ cup | 6 tablespoons |
| 4 fl oz | 0.5 c | ½ cup | half cup / small glass |
| 5 fl oz | 0.625 c | ⅝ cup | — |
| 6 fl oz | 0.75 c | ¾ cup | standard coffee mug |
| 8 fl oz | 1 c | 1 cup | 1 cup / ½ pint |
| 10 fl oz | 1.25 c | 1¼ cups | — |
| 12 fl oz | 1.5 c | 1½ cups | soda can |
| 16 fl oz | 2 c | 2 cups | 1 pint / standard bottle |
| 20 fl oz | 2.5 c | 2½ cups | large vending bottle |
| 24 fl oz | 3 c | 3 cups | sport bottle |
| 32 fl oz | 4 c | 4 cups | 1 quart |
| 40 fl oz | 5 c | 5 cups | — |
| 48 fl oz | 6 c | 6 cups | — |
| 64 fl oz | 8 c | 8 cups | ½ gallon |
| 96 fl oz | 12 c | 12 cups | ¾ gallon |
| 128 fl oz | 16 c | 16 cups | 1 gallon |
Standard measuring cup sets include ¼, ⅓, ½, and 1-cup sizes. Here is the exact fl oz value for each fraction used in everyday cooking:
| Cup Fraction | fl oz | Tablespoons | ml |
|---|---|---|---|
| ⅛ cup | 1 fl oz | 2 tbsp | 29.6 ml |
| ¼ cup | 2 fl oz | 4 tbsp | 59.1 ml |
| ⅓ cup | 2.667 fl oz | 5 tbsp + 1 tsp | 78.9 ml |
| ½ cup | 4 fl oz | 8 tbsp | 118.3 ml |
| ⅔ cup | 5.333 fl oz | 10 tbsp + 2 tsp | 157.7 ml |
| ¾ cup | 6 fl oz | 12 tbsp | 177.4 ml |
| 1 cup | 8 fl oz | 16 tbsp | 236.6 ml |
This is the most common source of confusion when converting oz to cups in recipes. Fluid ounces (fl oz) measure volume. Weight ounces (oz) measure mass. They are different units — despite sharing a name.
| Unit | Measures | 1 cup equivalent | Used for |
|---|---|---|---|
| Fluid Ounce (fl oz) | Volume | 8 fl oz = 1 cup | water, milk, oil, liquid ingredients |
| Weight Ounce (oz) | Mass | varies by ingredient | flour, sugar, butter, solid ingredients |
When a recipe says "1 cup of water," it means 8 fl oz by volume — not 8 oz by weight (though for water these happen to be nearly identical). When a recipe says "1 cup of flour," it means 8 fl oz of volume of flour, which weighs only about 4.25 oz (120 g) — less than half the volume-weight of water.
Practical rule: For all liquids in recipes — use the fl oz ÷ 8 formula from this page. For dry ingredients like flour, sugar, oats, or cocoa powder — weigh them in grams or weight ounces for accuracy. A kitchen scale removes all ambiguity.
Not all "cups" are the same. Recipes from different countries may use different cup sizes, which affects conversions from fl oz significantly.
| Cup Type | Volume (ml) | fl oz equivalent | Used in |
|---|---|---|---|
| US Legal Cup | 240 ml | 8.115 fl oz | US Nutrition Facts labels |
| US Customary Cup | 236.6 ml | 8 fl oz (exact) | US recipes, cooking |
| Metric Cup | 250 ml | 8.454 fl oz | Australia, Canada, South Africa |
| Imperial Cup | 284.1 ml | 9.608 fl oz | older UK recipes |
| Japanese Cup | 200 ml | 6.763 fl oz | Japan |
All calculator results and tables on this page use the US customary cup (8 fl oz / 236.6 ml) — the standard for American recipes. If you are following an Australian or Canadian recipe, their "1 cup" is 250 ml, which is slightly more than the US 236.6 ml.
The cup sits between the pint and tablespoon in the US customary system. Knowing its position makes multi-step conversions — like cups to gallons — fast mental math.
| Unit | fl oz | Cups | Pints | Quarts | Gallons |
|---|---|---|---|---|---|
| 1 tablespoon | 0.5 | 0.0625 | — | — | — |
| 1 fl oz | 1 | 0.125 | — | — | — |
| 1 cup | 8 | 1 | 0.5 | 0.25 | 0.0625 |
| 1 pint | 16 | 2 | 1 | 0.5 | 0.125 |
| 1 quart | 32 | 4 | 2 | 1 | 0.25 |
| ½ gallon | 64 | 8 | 4 | 2 | 0.5 |
| 1 gallon | 128 | 16 | 8 | 4 | 1 |
One cup is exactly half a pint and one-quarter of a quart. For gallon-scale calculations, see the oz to gallon converter. To convert in the other direction, use the oz to pint converter when pints are your target unit.
These are the most frequently needed conversions when following US recipes. Each value comes up often enough to be worth memorizing.
| Ingredient / Scenario | Amount in fl oz | In Cups | Notes |
|---|---|---|---|
| Stock or broth (soup recipe) | 32 fl oz | 4 cups | standard carton size |
| Milk (baking recipe) | 8 fl oz | 1 cup | one full cup |
| Heavy cream (whipping) | 16 fl oz | 2 cups | standard pint carton |
| Olive oil (large batch) | 4 fl oz | ½ cup | = 8 tablespoons |
| Orange juice (glass) | 6 fl oz | ¾ cup | standard serving |
| Coffee (standard brew) | 6 fl oz | ¾ cup | SCAA standard cup |
| Water (daily intake tracking) | 16 fl oz | 2 cups | standard water bottle |
| Pasta water (large pot) | 64 fl oz | 8 cups | ½ gallon |
| Smoothie recipe (blender) | 8–16 fl oz | 1–2 cups | depends on recipe |
| Salad dressing (batch) | 4 fl oz | ½ cup | mason jar serving |
| Brine (pickling, fermenting) | 32 fl oz | 4 cups | 1 quart jar |
| Sauce (canning recipe) | 24 fl oz | 3 cups | — |
Coffee note: The Specialty Coffee Association defines a "cup" of coffee as 6 fl oz of brewed coffee — not 8. This is why a 12-cup drip coffee maker produces about 60 fl oz (7.5 US cups) of actual liquid, not 96 fl oz. When your coffee maker says "12 cups," it uses the 6 fl oz coffee-cup standard.
Understanding where oz-to-cups conversions go wrong prevents recipe failures:
❌ Using a coffee mug as a "cup"
Coffee mugs range from 8 to 20 fl oz. Using a 12 oz mug as a "cup" adds 50% more of each liquid ingredient — enough to ruin a batter. Always use a calibrated measuring cup.
❌ Confusing weight oz with fl oz for dense liquids
Honey, maple syrup, and molasses are significantly denser than water. 8 fl oz of honey weighs about 12 oz (340 g) — 50% heavier than water by weight for the same volume. If a recipe specifies "8 oz honey by weight," that is only about 5.3 fl oz in volume.
❌ Treating metric recipes as US cup recipes
Australian and Canadian recipes use a 250 ml cup, which is about 8.45 fl oz — 5.6% more than the US 8 fl oz cup. For most recipes this difference is negligible, but for bread and pastry it can affect texture.
❌ Scooping flour into a cup instead of spooning
Scooping compacts flour and can pack 20–30% more into the cup than intended. The correct technique is to spoon flour into the measuring cup and level it off — or better, weigh it. 1 cup of properly measured all-purpose flour = approximately 120–125 g.
US fluid ounce and cup definitions follow the standards maintained by the National Institute of Standards and Technology (NIST). The distinction between fluid ounces (volume) and weight ounces is explained in detail by Encyclopædia Britannica. For a full overview of US measurement units, the USGS Water Science School uses cups and ounces in everyday hydration contexts.
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