# Problem with ContourPlot3D of a torus

I want to plot a torus using the equation of its surface

 With[{R = 106, r = 50}, ContourPlot3D[(Sqrt[x^2 + y^2] - R)^2 + z^2 == r^2, {x, -(R + r), R + r}, {y, -(R + r), R + r}, {z, -r, r}]]


But, but the torus shown is flattened. When I use {z, -(r + R), r + R} it works. Why does it not work with the interval from -r to r?

BoxRatios->{1,1,1/3}

• BoxRatios -> Automatic works too. (+1) – kglr May 23 at 1:28
• Your plotting ranges are from -156 to 156 in $x$ and $y$, but only -50 to 50 in $z$. Mathematica makes a default box of ratios 1,1,1 in scale (stretching each axis to fit). If you want a plot that is thin and flat (for instance), you'll have to change to BoxRatios. Clear? – David G. Stork May 23 at 2:02