My dear Chips, that's exactly what I thought!
First of all, did you read the packing sticky on top of this page? If not, it'll help.
Second, did you every weigh all your items on a postal or kitchen scale and make a list. The best packers do that. That's one of the reasons they are the best.
Now let's look at your items. You do sink wash. That is fabulous! However, why on day 7? Christian? Just kiddin'!
If this is a 10 day trip, I assume on day 1 you travel there and on day 10 you travel back, right? So instead of taking a charge of seven of each I'd take only 5. Wash at half time and wash less. Moreover, perhaps your employer does pay for laundry. In that case you could take even less and do laundry twice. Laundry is usually paid by piece so it doesn't matter if you do it twice. And they do the ironing for you!
Alright the items. I post your list here and then address each one or by category.
1 suit jacket
If you wear that on the plane you are already better dressed there. Just beware of carrying a bag with shoulder strap on your jacket's shoulder pads. That can quickly kill the suit. Otherwise pack it.
2 Suit pants
That's very good. You want a back-up in case you really have a bad wine mishap or something. And I see you probably also wear those in the evening. So that's great right there, too.
5 dress shirts
Perfect. That's all that's needed. You could take 6 dress shirts and leave all the casual ones at home.
7 undershirts (that go under dress shirts and casual shirts)
You talkin' ole wife beater or t-shirt? If that's t's that's too much volume and weight right there. Given that you only wear a dress shirt once, you don't really need an undershirt unless you are either sweating profusely or are in a very cold climate which I guess is not the case since you didn't necessarily list a jacket. I'd skip those completely. Not necessary!
5 pairs of dress socks
That's good and fits the 5 day washing scheme.
dress belt
Only take a single belt. Make it reversible. One side brown or textile, the other black to wear with your dress shoes. The brown or textile side will go with the jeans. Since you'll be wearing that on the plane, it's another 0.5lb less in your bag.
7 pairs of underwear (yes i do laundry or sink wash after 7 days)
Not necessary to have 7 if you wash on day 5. Take just 6. Or even just 5.
3 pairs of boxers
What for? You have already a pair of underwear for every day. Boxers are heavy and very bulky. Throw them out. Almost a pound less!
1 pair of workout shorts
3 workout shirts
5 pairs of workout socks
workout shoes
Holy!!! That's exactly what I thought. Man, that stuff weighs at least 5lbs in and of itself. Do you work out in the room or in the hotel gym? Even if you use the gym you won't need extra socks and if you use t-shirts as undershirts anyway (although I said not to bother) you can use those. No need for extra shirts.
OK, here's the deal. If you are not a super sports fanatic who cannot live without a gym, try out some isometric exercises. I can tell you from experience that there are bodyweight exercises that do as much for you as anything at the gym will. Especially there are back exercises that you can do for your back and neck in your room. So you can do these in the evening or in the morning in the underwear of the day that just passed. The stuff goes to laundry anyway, might as well sweat it through all the way. Seriously, try it out. You might really enjoy the newfound freedom and I know you will enjoy the lesser load of carrying and washing. If you do it in your hotel room you can even leave the workout shoes at home. Yay! You can easily save yourself 5lbs here.
1 casual longsleeve shirt
2 casual shortsleeve shirt
3 pairs of casual socks
It is my conviction - and any man savvy in things sartorial will agree - that short-sleeve shirts are hardly suitable for a grown-up man. You have dress shirts anyway. Unless they are totally crumpled and dirty/stinky they will do in the evening, too. So maybe take a couple of Polo shirts. Or actually take 7 dress shirts but leave all 3 casuals at home. That will save you about 1.5lbs. Each shirt is around 200g.
dress shoes
OK. Nothing to say here. You need those. But still you may be able to find a pair that is rather light weight. The big fat Alden Cordovan Bluchers are not ideal here. A light single-cut oxford would be much more appropriate. Look around and compare. It's an opportunity to lose another half pound.
tri-fold toiletry bag
The Horrrrrrooooorrr!
Terrible beginner's mistake I made, too. Don't do it, Chips. These things are super heavy and bulky. Mine weighs a pound EMPTY! Take two ziplock baggies. One for hardware (razor, brush, etc) and one for liquids. That'll totally do. When they are dirty or torn, just get a new one. 1lb less. Also go through the toiletries and see what you really need and if there are smaller sizes. Hardly a man needs 100ml of anything over ten days (talking cosmetics here, not whisky!).
Let's recap. We save:
1lb on the toiletry bag
0.5lb on lighter shoes (potential savings)
1lb on casual shirts (given that you might still take an extra polo instead)
5lbs on workout stuff
0.5lb on the boxers (perhaps even as much as a full pound)
0.5lb on the belt
1lb on the undershirts (assuming you still take one or two against my advice)
We are talking 9.5lbs here! That, dear friend, is the weight of a typical 22" carry-on roller (the bag itself). In volume it is almost one half of what fits into said roller.
Now, if you follow the advice given here, I swear you can fit the remainder of things into an IATA size hardside spinner that will pass muster even with the finicky gate agents in London and even with the evil folks at Lufthansa, and that means it will pass basically everywhere. I'm even quite confident that the remainder of the items will stay under the 8kg carry-on limit that many airlines in Asia and Europe now have, if that's important for you. IN any case, it's good for you because it means you now have two bags that are around 8kg each. This means that you can probably handle them easily without risk of pain or injury. And it means if you have to run, you can take 8kg in each hand and be balanced. ^
You win!
As an ideal bag I'd recommend the Rimowa Limbo Cabin IATA Multiwheel. Yes, I know, that's a mouthful.
http://www.rimowa.de/main#product/880.52.21.4
Fits through any sizer, weighs only 3.8kg (8.4lbs thus less than the stuff you just threw out), looks terrific and it has the fully rigid frame that makes maneuvering these cases soooo easy. It also has a completely flat top thus your briefcase will ride safely on top of it. As a side effect it does look terrific, too. IMHO the seal gray version is super spiffy.
What says ye? Ready for a complete game changer?
Till