This frustum cone area calculator takes the figures you already have and applies the relationship behind frustum cone area calculations for you, giving surface area of the frustum and slant height (s) from base radius (r), height (h) and top radius (r).
What Is the Frustum Cone Area Calculator?
The frustum cone area calculator works through base radius (r), height (h) and top radius (r) to give you surface area of the frustum and slant height (s).
It is aimed at the case where you know the method but not the arithmetic: schoolwork, a quick check on a worked example, or a figure that needs to be right first time.
How the Frustum Cone Area Works
Each step is applied in order and depends only on the values before it, which makes it possible to follow the calculation rather than take it on trust.
If you are working through the same problem by hand afterwards, compare the intermediate values. That is where a mistake usually shows itself.
Checking Your Own Working
Round sensibly as you go and keep the full precision in the calculator. Rounding too early is the most common way of getting a right method to give a wrong answer.
Where a result should be a whole number, such as a count, check it against the constraint that produced it. A fraction of a person is a sign that something upstream needs revisiting.
A Worked Example
Working through an example, with base radius (r) set to 10, height (h) set to 5, top radius (r) set to 2, the calculator returns slant height (s) of 9.43398, and surface area of the frustum of 682.378346. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out surface area of the frustum?
Enter base radius (r), height (h) and top radius (r). The calculator then works through the relationship and reports surface area of the frustum and slant height (s).
What does the frustum cone area actually calculate?
It takes base radius (r), height (h) and top radius (r) and converts them into surface area of the frustum and slant height (s) using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter base radius (r)?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.
Does anything you type get stored?
No. The whole calculation runs inside your browser, and nothing you enter is uploaded, logged or sent anywhere.