Use "ChiSquare Quantile" function. See following screenshot to see how the results match.
Notice, the Excel function use right-tail probability, and you need 1 minus that probability for the JSL function.
BTW, I am curious, under what situation, do you need to manually calculate this quantity?
![peng_liu_1-1653527199553.png peng_liu_1-1653527199553.png](https://community.jmp.com/t5/image/serverpage/image-id/42713iC4B5527847ECDC99/image-size/medium?v=v2&px=400)