Best exercise for bum and thighs but less impact on calves?

First of all, unless you are weight lifting and trying to gain muscle through eating a surplus you will not gain muscle in your calves or your thighs and glutes.

A newbie just starting exercising (especially weight lifting) can gain minimal muscle and maintain current mass, the gains taper off eating at a deficit to loose weight.

And when you exercise your legs, your calves, hamstrings, quads and glutes are all engaged. So thinking you can exercise just the upper legs with out the lower...well you see where I am going here..

When eating at a deficit to loose weight the goal should be to strive for strength and fitness and yes maintaining your current muscle mass.

Thin thighs in 30 days is an awesome program. U can google it. There is a book or u can find the article online with the exercise program. I actually downloaded the book for about $5 n it's awesome! Good luck

If you're serious about gaining muscle in your legs/glutes, you NEED to lift weights AND be eating in a surplus. Cardio will really only help burn calories. Try compound movements like squats and sumo deads. Your calves will get hit, but not be targeted. Some good isolation movements would be leg extensions, glute bridges, leg curls, and glute kickbacks. My all time favorite is the stiff-legged deadlift. It really hits the hamstrings and glutes. Personally, if I want my calves to grow, I really have to focus on them and do calf raises. They shouldn't gain a ton of mass if you don't train them directly.

Also, protein is extremely important for gaining muscle so be sure you're getting enough of it.

I hope this was helpful in any way. So pretty much, yeah, I think it's possible to gain mass in your quads/hamstrings/glutes without gaining much in your calves, it just takes work and time. Good luck!!!!