Opera attire

I went to the ballet in Vienna (same venue as the opera) and wore my non-jeans pants, a top and sweater with a dressy scarf and Skechers flats. I did not feel out of place, though of course there were people more dressed up.

Exactly what CWsocial said. I wore my good pants and best top to the opera in Vienna - There were a few people dressed to the nines, and a lot more dressed to the threes or fours.

I went to the opera and wore nice packable black pants and one of my better tops with a necklace, and black flats and felt that I fit in fine. In fact, a Viennese lady in the restroom struck up a conversation with me (in German), so I must have looked like a local.

There is no dress code at the Opera, but you are encouraged to avoid athletic wear.

You’ll see jeans and casual clothes. If you want to fit in, dark pants and a dark top is fine. Skirt is not required!

I would google the venue you are going to and look at interior photos during a performance ... generally very easy to find ... then rather making your decision on how you would feel dressed a certain way, ask yourself how those around you would feel.

I go to the Opera House in Budapest fairly often and the tourists are easy to spot, they are the ones that feel good about themselves but few of the locals feel good about. This question comes up often and the attitude is always the same "me, me, me". So the last two visits I did an informal survey. Out of about 1500 people I could count the men not wearing at least a sports coat on my 10 fingers .... excluding the $6 tickets in the balcony as I can't see the balcony from my box. But Vienna is probably more casual (actually my experience there) maybe because it's been watered down by so many tourists maybe more progressive attitudes ... not yet a problem in Budapest. So go look at the photos so you get a real impression and not someone's biased opinion.

You have to admit, Vienna has some spectacular venues https://www.google.com/search?q=Musikverein&tbm=isch&tbs=rimg%3ACShEaasN3G-9IkD7voUxTzTxnpgVjghyTUpf16k1UP2CILofxOkkD1_12MuLVRNSiOiwuWCfJ1d3qRMS2QuTb3zxCHIx421bEjglmKhIJ-76FMU808Z4RcYZhCbZRV18qEgmYFY4Ick1KXxFAo4QJR-XDSCoSCdepNVD9giC6ET82zGWwrDoNKhIJH8TpJA9f9jIRkjOs9nnAMIkqEgni1UTUojosLhFXwpsJhx6nlCoSCVgnydXd6kTEEf0lAZ3TenTnKhIJtkLk2988QhwRe3gSgn0BimMqEgmMeNtWxI4JZhFinQRYOK3Z5Q&prmd=mniv&hl=en&ved=0CBIQuIIBahcKEwigqenHrJLjAhUAAAAAHQAAAAAQEA&biw=360&bih=572#imgrc=C1r_pajAo4b-uM

Please wear what you feel comfortable in - business casual or perhaps black traveling clothes. My parents went to a matinee in the Opera House with traveling clothes and didn't feel out of place.

Dressing up to go out to plays is much more casual these days. Go to any play from NYC to London and people will come in wearing jeans. I'm just glad to see people coming in and enjoying the arts. Being uptight because of jeans seems rather stupid. IMHO.

And no-most locals won't care.