Lasts and Sizing

Nailing down the correct size on the lasts is the most critical step when buying an Alden. Who wants a shoe that doesn’t fit? This guide should help you in discovering the proper size for each Last. I will say up front that this is intentionally a guide and that on certain models, such as the Leisure Handsewn Penny Loafer, it is a three dimensional problem due to the vamp (top of the shoe) also being a factor.

What are the different lasts and how do they fit relative to one another?

Source: @REguy, Reference:

Anecdotal Sizing Information

From @mdubs:

Size Lasts
10.5C True-to-Size
10C Van
10.5B Barrie, Modified, and Trubalance
10.5C Copley, Grant, Leydon, and Tremont (AE 5-Last for reference)
11B Hampton, Plaza, and Aberdeen

From @NewYorkRanger:

I find the Modified last (for my foot) is wider than the Barrie. 9D Modified fits me great, while 9D in Barrie is a snug fit, the E width for me in Barrie is too wide. I find the Trubalance last to be a little bit bigger overall last to the Barrie, whereas the Modified has a more tapered mid foot under the arch, opening up to a wider forefoot.

From @borderline:

Normal size is 10.5D, I take a 10D in Barrie and 10.5E in Leydon

From @Pastor:

I wear a 9 D in the Barrie and i’ve also tried a 9E in the Barrie. I won some of each and wear them both. The 9D is a little snug and the 9E is a little loose. I have a pair of 9.5 D leydon lasted LWB and they fit great. I went with a 9.5D on the grant.
9.5 E in the Dalton and most all AE’s
9D in the truebalance (almost perfect fit)
9.5 D in grant ( perfect fit)
9.5 D in leydon (perfect fit)

From @dsmivtr:

I wear 6.5D Barrie and the 7D Grants fits well for me (actually 6.5E also works fine).

From @kippy:

If you size down 1/2 for barrie (say 10E to 9.5E), don’t try to size down 1 and go wider (to 9EE)

From @MiniW:

the best way to determine fit and comfort is to ensure that the ball of your foot is at the widest part of the shoes. some people may have short toes and some people may have longer toes but using that area as a reference point has always worked well for me. Also there is just a feel when you put on a pair of shoes if it feels slightly too large or slightly too tight. If you think it fits you well and is not causing any pain or slipping off when you lace them, then they are likely the right size.