Finding the volume of an oval, such as a casserole dish, is easy. Fill it up with water, pour the water into a measuring cup and read the markings. However, if you have an oval horse trough, this solution becomes impractical. For applications too large to lend themselves to the measuring cup solution, you’ll need to apply a little bit of basic geometry. Unless you’re a math whiz, you will also need a calculator. In case you’ve forgotten your high school geometry, pi = 3.14.

- Measurements (length in both directions and depth) of the oval
- Pencil and paper
- Calculator
If your container measures 6 feet across the long side of the oval, 4 feet across the short side and is 4 feet deep, the equation would be: 4 / 3 * 3.14 * 3 * 2 * 2 = 50.26 cubic feet. If you don’t have a calculator at hand or don’t want to plug the formula in by hand, the calculator page in resources will give you the answer if you enter the values of r1, r2 and r3.

Find the radius of each dimension by dividing the measurement in half. If the width is four, the radius will be two. If the depth is six the radius will be three, etc.

Write down your answers on a piece of paper. Label them r1, r2 and r3. It doesn’t matter which dimension you assign to each label as long as you get all three measurements.

Enter the following into your calculator: 4 / 3 * 3.14 * r1 * r2 * r3 =. When you hit the = key, your answer will appear on the screen. Substitute the numbers you wrote down in step 2 for r1, r2 and r3. In this formula, the " / " is used for the division sign and the " * " is used for the multiplication sign.

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- the calculator image by Ilja MaÅ¡Ãk from Fotolia.com