Day trip to Cinque Terra form Lucca

Doable? Yes. You and about 50,000 other people. Takes about 2 hours from Lucca. Trains run very frequently between the 5 towns and La Spezia, so just go as you please. Maybe start in Vernazza.

Thanks Sam. Should I go? Didn't realize the crowd size. Thank you.

Why not? I am probably exaggerating, but day trippers on the weekends are a factor.
And how is the toilet paper business?

Go early or go in the evening if possible or stay the weekend so you can hike and see it without the day trip crowd

I went to Cinque Terra from Lucca, but I would never have done it as a day trip. And I planned my 3 night stay so that it fell on the weekdays....arriving on Tuesday and leaving on Thursday.
I also checked the cruise ship schedules to avoid the most busy landings. Even so, there were many people, but in the evenings and early mornings very pleasant. If you are fit enough to hike the high trail (not the blue trail near the sea) you fill find only a few people walking the higher trails. I went in mid May.

Thank you Ann. I with take your suggestions into consideration. I forgot about the cruise ships.

As the others have said, a day trip from Lucca to the Cinque Terre is certainly feasible. Weekends could be more crowded, although it may be quieter at that time of the year.

The trip will take about two hours in each direction. On the trip to the C.T., you'll be using a variety of trains depending on which departure you choose and some will invariably be Regionale trains. Be sure to validate locally purchased tickets for those trains prior to boarding the train on the day of travel, or you'll be subject to hefty fines! If any segments will be on Freccia or Intercity trains, those have compulsory seat reservations and tickets don't need to be validated. If you want to get an early start to maximize your time in the C.T., there's a departure from Lucca at 07:59 (the next one isn't until 09:30).

I'd suggest starting in Riomaggiore and then working north from there using the frequent local trains (or the boats if they're running). Note that the boats don't stop in Corniglia. Try to time your touring so that you end up in Monterosso at supper time, so that you can enjoy a fine meal in one of the restaurants there. Cantina di Miky is a favourite with many here (it's close to the train station). Try to allow more time for Monterosso, as it has an "old town" and a "new town", so will take more time to see. If the weather is nice, you may want to sit on the beach and just enjoy the view.

If you return to Lucca from Monterosso, there are departures with only one change at 19:07 and 21:07 (travel time 1H:20M), and a departure at 19:42 with two changes (travel time 1H:45M).

Buon Viaggio!

Thank you Ken.