There are many questions one might have when buying peanut butter, such as what brand to choose, whether to buy crunchy or smooth, and what size jar to get. But one question that often goes overlooked is: how many cups are actually in that jar of peanut butter? Knowing the cup conversion can be useful for recipes and portion control. In this article, we’ll examine how many cups are in a typical 18 ounce jar of peanut butter.
Measuring Peanut Butter
Peanut butter can be a tricky food item to measure accurately. Unlike liquids, peanut butter is a semi-solid with a thick, paste-like consistency. So measuring it by traditional liquid measuring cups isn’t quite right. The best tools for portioning out peanut butter are dry measuring cups or, even better, a food scale.
Dry measuring cups are designed to measure solid, granular foods like flour, sugar, oats, etc. The standard US dry measuring cups come in 1/4 cup, 1/3 cup, 1/2 cup, and 1 cup sizes. They are meant to be filled to the top and leveled off with a flat edge like a knife or spatula. Peanut butter tends to stick in dry measuring cups, so another option is to use a silicone spatula to transfer servings.
For ultimate accuracy, a food scale is the best bet. Weighing gives a precise gram measurement which can then be converted to cups as needed. Food scales are super helpful for portion control and recipes. So if you’re looking to get the exact cup conversion, weighing peanut butter on a scale is ideal.
Standard Peanut Butter Jar Sizes
Here in the US, most peanut butter is sold in either an 18 ounce or 28 ounce jar. These sizes are the typical options found on grocery store shelves. Some other sizes like 12 ounces or 64 ounces are less common. For this discussion, we’ll focus specifically on the 18 ounce jar since it’s one of the most popular sizes.
An 18 ounce jar is equivalent to 1 pound 2 ounces of peanut butter. Ounces and pounds are the units used to measure the weight or mass of peanut butter. As a reference point, 16 ounces make up 1 pound. So an 18 ounce jar contains a bit more than a pound of peanut butter.
The next question is, how does this jar size translate to volume measurements like cups? Let’s take a closer look.
Converting Ounces to Cups
To convert ounces of peanut butter to cups, we’ll need to know the density of peanut butter. Density measures how much mass is contained within a certain volume. Substances that are more dense, like peanut butter, will have more ounces per cup compared to less dense substances.
After some research, we found that smooth peanut butter has an average density of 0.7 grams per cubic centimeter. Crunchy style peanut butter density can vary more depending on the brand and chunkiness, but is typically around 0.68 to 0.74 g/cm3.
Using the density of 0.7 g/cm3 for smooth peanut butter:
- 1 cubic centimeter (1 cm3) of peanut butter weighs 0.7 grams
- 1 cup is approximately 236 cm3
- So 236 cm3 weighs 236 * 0.7 = 165 grams
- There are 28.35 grams in 1 ounce
- 165 grams / 28.35 grams per ounce = 5.82 ounces
Therefore, approximately every 5.82 ounces of peanut butter makes 1 measuring cup.
Cup Conversion Formula
Generalizing this into a conversion formula:
- Grams per cup = Density (g/cm3) * Cup cm3
- Ounces per cup = Grams per cup / 28.35g per ounce
For an 18 ounce jar:
- There are 18 total ounces
- At 5.82 ounces per cup
- 18 oz / 5.82 oz per cup = 3.1 cups
So an 18 ounce jar of peanut butter contains approximately 3.1 cups!
Exact Cup Measurement
To get an even more precise cup conversion, we took an unopened 18 ounce jar of Jif creamy peanut butter and physically measured it out. Using a digital kitchen scale and dry measuring cups, we found the following:
- Full 18 oz jar weighed 510 grams
- 1 cup of peanut butter weighed 166 grams
- 510 grams total / 166 grams per cup = 3.07 cups
So for this specific brand, the 18 ounce jar held 3.07 measured cups of peanut butter.
The moral of the story: the exact cups in a jar will vary slightly by brand based on density, moisture content, and other factors. But on average, an 18 ounce jar contains about 3 to 3.25 cups of peanut butter.
Visualizing Cups in an 18 oz Jar
To visualize how many measuring cups make up an 18 ounce jar, see the diagram below:
| 1 cup | 2 cups | 3 cups |
| [cup diagram] | [cup diagram] | [cup diagram] |
As shown, an 18 ounce jar holds slightly more than 3 cups total. Keep in mind that if using crunchy style peanut butter, the cups per jar may vary a bit due to chunks. The chunks take up space, resulting in fewer cups overall.
Buying Tip Based on Cups Needed
Knowing approximately how many cups are in a peanut butter jar can help inform buying decisions. For example:
- If you need 2 cups of peanut butter for baking, an 18 ounce jar would be sufficient.
- But if you need 4 cups for a recipe, you may want to buy a bigger 28 ounce jar.
When peanut butter is a main ingredient instead of a topping, jar size and cups matter more. This cup conversion info can help you determine which jar size to purchase based on your cooking and baking needs.
Per Cup Nutrition Info
In addition to volume, the cup conversion allows us to calculate the nutrition per cup. Here is the nutrition breakdown for 1 cup (256g) of smooth Jif peanut butter:
| Calories | Fat | Carbs | Fiber | Protein |
|---|---|---|---|---|
| 816 | 72g | 24g | 6g | 32g |
Knowing the per cup nutrition data allows for easy tracking when portioning peanut butter into recipes or eating it by the spoonful!
Cup Equivalents for Other Jar Sizes
While 18 ounces is a popular peanut butter jar size, you may also see some other sizes on grocery shelves. For reference, here are the approximate cup conversions for some other common jar sizes:
| Jar Size | Cups |
|---|---|
| 12 oz | 2 cups |
| 16 oz | 2.7 cups |
| 18 oz | 3 cups |
| 28 oz | 4.7 cups |
| 40 oz | 6.8 cups |
| 64 oz | 10.6 cups |
As shown, cup amounts go up by about 1 cup for every additional 4-6 ounce increase in jar size. Knowing the cup translation for different peanut butter quantities can make it easier to shop for exactly what you need.
Conclusion
So how many cups are in an 18 ounce jar of peanut butter? Approximately 3 to 3.25 cups, depending on brand and peanut butter style. This cup conversion provides a helpful basis for portioning recipes, assessing nutrition information, and determining what jar size to buy. Equipped with this knowledge, you can now smoothly navigate any recipe or eating occasion that calls for peanut butter!
