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Round Kiln Shelf Fit Checker

Enter the radius of the shelf, the radius of the pot, where its centre sits and the margin you want to keep from the shelf edge. You get a clear fits or does not fit, the room left or missing, and a drawing.

Result

Fits

4 cm to spare · far edge plus margin reaches 16 cm from the centre · largest offset for this pot and margin: 14 cm

Geometry and arithmetic only. It does not check the load, the elements, the heat or the safety of a firing: follow your kiln maker's manual.

How it works

  1. Enter the shelf radius and the pot radius, in the same unit.
  2. Enter the position of the pot centre from the shelf centre (x and y) and the margin to keep.
  3. Read whether it fits and by how much, and the largest offset allowed.
  4. Check the drawing, then copy the result.

What people use it for

  • Placing one large pot

    Find how far from the centre a wide plate can sit before it passes the edge margin.

  • Round shelf, round work

    Try several offsets without redrawing the shelf each time.

  • Checking a plan on paper

    Confirm a position taken from a sketch with the numbers.

Questions

What is the rule?
The pot fits when sqrt(x² + y²) + pot radius + margin ≤ shelf radius. The distance from the centre uses x and y, so a position along a diagonal is handled the same as one along an axis. The largest allowed offset is shelf radius − pot radius − margin.
Does it work for pots that are not round?
Only if you use the radius of the smallest circle that contains the pot as seen from above. For a rectangle that is half its diagonal. The page does not model other shapes.
What margin should I use?
The page does not recommend one. Use the clearance your kiln maker gives for shelves and your own experience, and enter it yourself.
Is a fit the same as a safe firing?
No. It is a distance check only. It does not look at weight, the elements or how the pot will behave in the kiln.