Calculator works, but You need to add one more field. I believe chain speed is measured in inches per minute, IPM. Manufacturers do advertise ft per sec.
Formula, Take the chain pitch and multiply by 2. Multiply the above number by the number of teeth of the saw sprocket.
Multiply that number by the saw R.P.M.
The final answer will be the chain speed in inches per minute, just divide by 12 to convert to feet per minute.
At any rate, for folks interested in building a hydraulic chainsaw, this type calculator is very helpful when trying to decide how big a hyd motor to use. Sprockets can be bought in various tooth counts over what is available for a gas chainsaw. You can play around with different size hyd motors and oil flow and sprocket size to get a chain speed similar to your favorite gas powered chainsaw and know you will have a hyd saw that will work. Saves a bunch of trial and error and possibly money when it comes time to buy parts.