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Sporty's Flight calc and mph vs kts ...


How's your marmott?
Feb 21, 2002
Total Time
It appears I can no longer remember basic mathematics, despite completing an Industrial Engineering degree, and my brain is begining to hurt.

I use Sporty's Flight Calc for all my planning and we've been renting an L-model Skyhawk lately. When performing the basic GS, heading, and time calculations (which I always still do) I've been multiplying the mph figures x 1.15 to convert to kts before entering numbers into the calc functions for GS, heading, time, fuel, etc. Is there an easier way to do this? It seems I'm doing things the hard way, but I can't get my brain around the calculator to see how the final figures will be affected if I just use MPH throughout the calculations.

Can I just plug mph into the formulas or will the result be skewed?


"My brain hurts."

"It'll have to come out!"


Well-known member
Nov 26, 2001
Total Time
It's been a long time since I've used one of them thangs, but my recollection is that you have a choice to use either SM & MPH or NM & Knots from the beginning of the calculation, making conversion unnecessary.

When you do convert, make sure you DIVIDE your MPH by 1.15, not multiply, to get knots. Obviously, the same goes for SM vs. NM.