Writing good smooth feeling swipe code

Currently I’m working on a game where swipes play a large part(moving cards around mostly) and I’m trying to find the smoothest feeling way of doing it.

Here is some code from what I have tried so far.

accel += event.tfinger.dx*width
    if(accel) accel -= vel/3 + 2*accel/3
    else vel=0;
    x += vel;

This feels pretty smooth but a little hard to control and bouncy.

I’ve also tried:
x += 1.5event.tfinger.dxwidth
Which is really easy to control, but feels jerky.