Changing Airlines Onroute - Luggage Rules?

Outbound should be using United's luggage rules.

When you say "Coming home we will be on Lufthansa" what's the specific routing and whose planes will you be on?

I assume both ways you used United miles to book these flights - correct? Coach or business class?

LOT and United are Star Alliance members, so luggage should be checked through all the way from Sacramento to Budapest, but as far as carry-on sizes go, that is usually the individual airline's rules that apply.

Thanks. I should have been more specific. I booked RT including one internal flight mid trip using United miles. We are flying coach. From Budapest to Munich we will be on a Lufthansa flight, then later we will be on Lufthansa from Luxembourg to San Francisco via Munich. If I understand this correctly, the United rules might apply on our outbound flights, but there is no guarantee that LOT would go by that at LAX or WAW? I understand Lufthansa rules would apply on their flights.

Andrea,

Sam nailed it.
If you are on one ticket: Sacramento to Budapest and if you check your bags all the way through then United’s rules apply.

I assume your internal flight out of Budapest to Munich is later then Lufthansa’s rules would apply.

Your return flight home on Lufthansa would be subject to Lufthansa’s rules.

All of the above is for checked luggage Only.

Cabin luggage (carry on) each individual airline’s rules apply (although many airlines slide on this in your type of ticketing as your not checking in for the connecting flight if you received all your boarding passes in Sacramento). Thus outbound you technically need to meet United and LOT’s rules for your carry on weight.

In situations like this I would never check bags from Sacramento to Budapest, especially considering that you will be flying on 2 different airlines on the way over with what sounds like a stop in Warsaw. I'd carry on and go by the most restrictive airline's rules. Of course, those basic rules can be more restrictive the less you pay for your flight or the lower your class of ticket.

Below is what I found for each airline, but I'd pay attention to what the ticketing documentation says.

United Airlines: These rules seem the most generous, but it looks like that route from SMF to LAX is operated by SkyWest. They use smaller planes. Scroll down to the bottom of this link to see the 2 major types and their sizes. This info on exceptions to the carry-on policy is linked in the body of the UA rules, but easy to miss.

Be sure to find out exactly what plane will be used and what the carry-on issues might be. Our son is a Captain with SkyWest, so I fly them frequently. A typical 22x14x9 bag may have to be gate checked. Collecting it as you get off the plane might be possible, or it might be sent to the carousel. I've experienced both.

LOT: This appears to be from the website, but the info on intercontinental flights is a little confusing.

Lufthansa: It looks like both LOT and Lufthansa have equally challenging carry-on restrictions.

Note that 55x40x23 cm = 21.5 x 15.7 x 7.8 in. These are the carry-on dimensions for LOT and Lufthansa. As is typical for many European airlines, height and depth are smaller and width is wider than 22x14x9. Both have 8kg ( about 17.5 pounds) weight restrictions for the carry-on bag. This is where you want to have the lightest weight empty carry-on possible.

I didn't dig into the size and weight restrictions for personal items. You can get to those from some of the links provided.

Many foreign items weigh your carryon, so the smaller size is not the only factor to consider. Your carryons will need to meet the size and weight requirements of the most restrictive airline that you are flying on-Lufthansa's requirements are likely smaller than United's.

Note: I carry a 21" swivel wheel Travel Pro carry on bag. But with the wheels, it's actually 22". I have no problems going over to Europe with the legacy air carriers. But when I get over there, I often get hassled by gate agents--trying to make an example of me. I usually win the disagreement by holding up the gate and arguing calmly, but sometimes lose.
But I'm never going to wait in a fleabag Atlanta Airport hotel for 2 days again for my bags--with my electronic car key in them.

David, I assume you never put your electronic key in your luggage anymore? LOL

With a mileage trip, do you get a checked bag free on each flight ? How about taking carry-ons to meet the most restrictive requirements and checking one bag through with stuff that you can survive without for a few days if the bag gets delayed ?

Thanks to all for your comments. Laura B, on international trips we have gotten a free checked bag on the airlines we have flown so far, which are United, Air Canada and Lufthansa. I just bought the new RS spinner carry-on bag and plan to use it. I take a carry-on bag such as this and a backpack for my personal bag. I suspect my backpack might be considered too large for international carriers. It seems some may not allow a personal bag at all? My hubby has used his RS convertible carry-on for years plus a day bag, but we haven't discussed what bag he will take on this trip. Different rules should apply for our flight from Budapest-Munich because it's not an international flight. This is an 8+ week trip, spanning from the beginning of September to the beginning of November.

Even though you paid for you air travel using "miles" you booked with United and should have a United ticket defining baggage rules. The United ticket checked baggage rules should apply to the ticketed itinerary. That said, the size and weight of your carry-on baggage is controlled by the operating carrier and policed by the operating carrier's gate agents.