Through other software I managed to obtain a spline with length of 200mm. [![enter image description here][1]][1] The points would be these: pts = {{0, 0}, {45, 10}, {75, -15}, {130, -20}, {180, -33.25904718}} The last value in Y (`-33.25904718`) is not accurate for this directly depends on the length of the spline, that is 200. 1. I get this value in the SolidWorks software, but how can I get this value using Mathematica? And another question: 2. There is only one solution or there may be several other? **EDIT :** Through the comments of [Michael E2][2] I think the answer is this documentation, but I couldn't find a way in which the length of the BSpline is an input. [BSpline][3]->Applications->Interpolation [1]: https://i.sstatic.net/lxEn8.png [2]: http://mathematica.stackexchange.com/users/4999/michael-e2 [3]: https://reference.wolfram.com/language/ref/BSplineCurve.html?q=BSplineCurve