A stout one would be 34-35 mm high at the machi, 25-26 mm at the yokote. More in the tachi area would reduce those by two to four mm each. I prefer 34/24 myself. The long tip stuff has far less taper, only 5mm instead of 10.
The shinogi is classic at one third of the blade, tapering right along with the shape as it narrows towards the tip. The hamon should also be one third of the blade. All of these are subject to variation.
Thickness is just under 5/16 at the machi, measured at the shinogi, not the spine. A classic blade tapers upward from the shinogi as well as down to the cutting edge. I taper to a light 1/4 at the tip. on the shinogi line. The spine is cut a little narrower. If you want the tip flare to come out right, don't mess with it until after hardening.
I like a longer tang than you see on most antiques, around 9 to 11 inches. You can always shorten one, but its hell to add some when it comes up too short for the handle. The line of the top of the tang should not project above the line of the blade spine, unless you're making a tachi. The tang has to taper harmoniously, matching the blade. It's also thinner at the butt than at the machi, but not as precisely defined. Tangs on the sword are a little over 1/4 the blade length (cutting edge), but not quite 1/3. Average would be 8 1/2 to 9 inches on a 27 inch blade.
Curvature can run from 3/8 inch to about 1 inch. I like 5/8 to 3/4 myself, for a pure, classic form. Any curve over an inch is going to be a little awkward to use. I usually try to get the main part of the curve just a hair farther back towards the tang but the classic is to have it centered and even.
Average length for an antique, is about 26 1/2 to 27 1/2, although there are a lot of exceptions. Most of the guys want 20 to 30 inches now, a few at 31. Ideally, when the sword is held in the right hand and swung down, the tip should not drag on the ground. If the users knuckles drag on the ground, ignore that rule.
The cutting edge is a Moran style, with the grind running up that flat about half its width.
A traditional wakazashi is about three quarters of a sword.
Dimensions would be about as follows.
Height at the guard, 24 to 28 mm
Height at the tip break, 18 to 20 mm
Thickness at the guard, 1/4
Thickness at the tip, 3/16
Length, 19 to 22 inches
Length of the tip, 1 1/2 times height at the tip.
Length of tang, 1/3 the length of the blade
Curvature, 1/4 to 1/2 inch, measured on blade only
The grind line is at the 1/3 mark from the spine, and it tapers to match the blade.
The grind line within the tip is a radius from the same point as the cutting edge of the tip, and the same width as the lower part of the blade at the tip break.
The area above the grind line tapers inward slightly to the spine, but not as steep as the cut down to the cutting edge. This is reversed about two inches behind the tip so that the tip flares a bit behind the point where the tips grind line meets the spine.
The tang curves to match the blades curve and the extended line of the tangs spine does not project above that of the blade spine.
Curvature should be even, or centered slightly behind the center of the blade.
The width of the hard part of the edge should cover half of the lower grind, and it gets a Moran style edge.
The hammer and tongs fellows see the blade quite differently. They have to figure in extra thickness and width to allow for cleaning up all of the small hammer marks and other variations that you get in forging a long, slender shape.
Taken from a series of emails by Bob Engnath in response to questions from Daithi.