I have a Shimano Ultegra SG-X 50F Crankset with a 10 speed cassette.
When I upshift using the front derailleur it seem to be the same as upshifting two clicks with the rear derailleur.
Is there a way to calculate the ratio of how effort changes with the two types of shifting?
Is it about 2 to 1?
Thanks!

Sheldon Brown's Bicycle Gear Calculator

It's simple ratios and depends on specifics.

I run tight cassettes like 13-14-15-16-17-18-19-21-23-26 10 cogs, 13-23 9, 13-21 8.

Riding 50-39, shifting from the 39 to 50 while in the 19 cog is like going to the 15 cog 4 away

39/50 * 19 = 14.82 rounding to 15 4 cogs away -
39/53 * 19 = 13.98 rounding to 14 5 cogs away
34/50 * 19 = 12.92 rounding to 13 6 cogs away

OTOH, running 11-12-13-14-16-18-20-22-25-28-32 11 cogs

39/50 * 20 = 15.6 rounding to 16 2 cogs away
39/53 * 20 = 14.7 rounding to 14 3 cogs away
34/50 * 20 = 13.6 rounding to 14 3 cogs away

Mike Sherman's gear calculator offers a nice graphical representation which can show equivalents, where you'll shift, and where you'll notice gaps based on your preferred cadence range.



With 50-34 x 13-23 I was in good shape on spacing, but was making 5-cog double shifts from 34x14 to 50x19 speeding up past 18 MPH and 50x21 to 34x15 below 16. I switched to 50-39.

the simple answer to your first question is yes.

and the answer to your second question is yes, if the tooth count on the big chainring is about, to use the same level of accuracy, twice that of the little chainring.

Actually it is more like 1 1/3 to 1 1/2 on common setups like 53/3/9 and 50/34.

Thanks to all for the good info and links.
This is a bit more complicated than it seems.

Just seems complicated. Map out your particular gears on a gear chart, then you will see how YOUR gears overlap. Everyone is different.

It's as complicated as you want to make it. If you can reliably find the right gear without too much extra shifting, you're doing fine.