Online Cone Calculator

My entry ‘Constructing a Cone’ was much to wordy ;-), therefore I wrote an online cone calculator.


Note: Unfortunately the online cone calculator seemingly doesn’t work under all circumstances and I don’t have the time to struggle through. That’s why I write the formula by all means behind.

Well, you have disabled javascript, which means that the online cone calculator doesn’t work anyway.

You have 2 options now:

  • enable javascript
  • calculate the cone data yourself using the following formula.


The black cone is what we want to get.
small diameter = smaller desired diameter
large diameter = larger desired diameter
height = desired height
QT = small diameter / 2
RS = large diameter / 2
PQ = QT * height / (RS – QT)
PR = PQ + height

PT = √((PQ * PQ) + (QT * QT));
PS = √((PR * PR) + (RS * RS));
(√ is sqrt is square root)

angle to cut away =
360 * (1 – ((2 * π * RS) / (2 * π * PS)))

inner circle diameter = 2 * PT;
outer circle diameter = 2 * PS;

unikatissima Example Cone

And now proceed:
Draw two centered circles with the inner and outer diameter, draw the calculated angle and cut it away.
The result should be a template for a cone with the specified measurements ;-)
If you don’t have a protractor you can print and cut the degrees disk from the entry ‘Constructing a Cone’.

If you want to know more exactly what you’re doing here, check the entry ‘Constructing a Cone’ after all ;-)

Here at unikatissima: ‘Constructing a Cone’

21 thoughts on “Online Cone Calculator”

  1. Thank you for this calculator, and for the other article where you explain the geometry behind it!

  2. Appreciate your effort. I’m always looking for examples to show my children why the should study maths.

  3. orly,

    I love being an example to children ;-))
    But you’re right of course: math can be sooo helpful at times!

  4. Thank you sooo much for this. I used the above to make a combustion chamber for a pulse jet engine lol. It worked first time and was perfect. Saved me many hours of mucking around :-)Many thanks

  5. Tony,

    I’d never thought that you’d need a cone to make a combustion chamber for a pulse jet engine!
    But then, I’m glad that I could help you :))

  6. Worked it through three times, three different results none of which looked convincing. Used your machine and at last a decent result, and I thought I was good at maths! Thanks.

  7. Phil,

    How good that it worked for you! :)

    And by the way: I feel that you’re not bad at maths only because you have problems with such a calculation! ;-)

  8. Aaron,

    “Does this factor in any overlap?”
    No, it doesn’t.
    You’ll have to make an overlap on your own.

    Enjoy and good success!

  9. Thank you for putting all of this information in one place and writing it in a way that is easy to grasp. Much appreciated!

  10. Is there a way to make a digital template of the cone for making lampshades? I would like an exact size Jpeg image so that I can paste graphics and images onto the template and then print out . I can easily add an overlap when cutting out the final printed cone.

  11. SN, thank you for your interest.

    Sorry, I cannot provide such a picture, but have you checked my entry Constructing a Cone?
    I describe there how to use the information you get with this cone calculator to immediately make a template without the use of a printed picture.

    I hope that this helps you making your lampshades.

  12. Thanks for your calculator! I’m making a reducer for a car wash drying system that should help increase the air velocity as it exits the blower and then enters the cylinder with the reducer. I would have spent much more time using my super old cone formula that I have to enter a boatload of values into my my ti 35 and hope I didn’t make a mistake! Thank you again. Doug

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