Colmar and Strasbourg for 2 days

Are you traveling by public transport, or with a rental car?

According to Rome2Rio, Strasbourg is right on the train line from Colmar to Paris, so you should be able to take the train from Colmar & Strasbourg and back for your day trip, then get on the train again to travel to Paris.

The RS Guide to France includes sections on both Colmar and Strasbourg with listings for lodging, restaurants, and things to see and do.

to be clear - are you saying Paris to Colmar, sightsee Colmar for a few hours, sleep in Colmar, up the next day, travel to Strasbourg, sightsee Strasbourg in a few hours, then back to Paris and sleep?

Or is there one night in each of Strasbourg and Colmar?

Are you driving or on the train - it will make a big difference.

Is the trip "back to paris on our last day." just before an international flight on that same day?

@ Nigel

My plan is to take a train From Paris to Colmar
Spend 1 night in Colmar
Then the following day travel to Strasbourg maybe before lunch , sightseeing for a few hours, then go back to Paris in the evening ...

Tnx

At least you are taking the train. Otherwise this already difficult side trip would be impossible.

Train from Gare de l'Est to Strasbourg, change to train to Colmar. (zero to 2 changes, 2 and a half hours)
or
Train from Gare de Lyon to Mulhouse, change to train to Colmar. (around 3:45)

Look around the old town. You don't have time to get to any of the villages around.

Next morning train to Strasbourg. (32 minutes plus tram) Look around Strasbourg, perhaps the Cathedral and perhaps Petite Venise. Back to the station and train back to Gare de l'Est. (tram plus 2 hours).