From the EK website ‘Wheelie’ bags - Please note that rolling bags with built-in wheels and retractable handles will be permitted as cabin baggage only if the total dimensions (length, width and height) add up to less than 45 inches (114 cm). The larger, overnight models of this type of bag will not be permitted in the cabin.

I measured my bag and it comes out to 47 inches overall 21x16x10... Will they give me a huge problem with this?

It's so inconsistent. The last couple of times ex-JFK I have not had a problem but did have to argue it out with a little twerp at KHI a few months ago who whipped out a measuring tape on me. This is a classic case of YMMV.

I will be flying out of DXB and PEK...

The bag is going to be over 15lbs though. These carry on restrictions seem very very limited. US carriers, carry on item + a personal item.... Usually means everything PLUS the kitchen sink... LOL

Personally, from my experience, I think the inconsistency has to do with the flight loads. 1st time out of JFK, coach went out with most of the middle seats open. Very light flight load. I had no problem with my bag then, neither did all the people who bought a crap load of stuff from duty free + laptop bag + wheeled bag.
Out of DXB, still light load but not quite as light. People had to check their second bag or the wheeled bag if it was too big.
My last flight out of JFK was a nightmare. All around, not just baggage. We just moved to DXB, so I had all my jewelry, marriage and financial documents, diplomas, etc in my carry on bag. The flight was oversold. They stopped everyone in coach, measuring the bags, weighing the bags. I ended up in tears because they were belligerent, insisting I couldn't take this wheeled bag on (its smaller than a 22'', maybe like a 20"). In the end, the ground crew left the decision up to the porter who took my bag and placed it with his in the cabin crew area. But there were some other people who were not as lucky. It was a mess.

Any idea what EK charges for additional bags?

Probably 1% one-way F-fare per kilo. That's the standard with airlines.

iv paid excess baggage at £32 per kilo a few times... Normally they can be quite flexible!

I paid $405 out of JFK for 3 extra bags. That was just for excess bags. Extra bags and excess weight would have been more. They didn't weigh the bags, just gave us a slip with 3 written in the excess bag column, we bought it over to the ticket agent and paid.

Just found the email reply from Emirates for their US policy


NOTE:-

Bags weighing between 23kgs-32kgs (50lbs-70lbs) will be subject to an overweight fee of USD50 per bag/piece. The maximum weight of any bag/piece may not exceed 32kgs (70lbs) even when paying overweight fees.

USD135/- will be charged for any additional bag/piece checked-in up to 23kgs (50lbs). An additional weight on the extra piece will be charged as per above rates also.

I am flying DXB-PEK dose this still apply?

the cabin baggage policy is so inconsistent...if you board late you are most likely to have your bag put in the hold if no room in overhaed lockers. If worried, board early and you should not have any problems