The chart decides the size, not the dog

A weight is not a crate size until you run it through a manufacturer’s chart, and those charts are recommendations rather than a standard. MidWest’s iCrate single-door line reads 24 in = 12-20 lbs, 30 in = 21-40 lbs, 36 in = 41-70 lbs, 42 in = 71-90 lbs, 48 in = 91-110 lbs, with an 18-inch for tiny breeds up to 10 lbs and a 22-inch for extra-small breeds up to 15 lbs. Precision’s ProValu2 line reads 24 in = 15-30 lbs, 30 in = 30-50 lbs, 36 in = 50-70 lbs, 42 in = 70-90 lbs, 48 in = 90-125 lbs.

The disagreement narrows as dogs get larger. At the nominal 42-inch size, MidWest says 71-90 lbs, Precision says 70-90 lbs, and Frisco’s Large in the Fold & Carry line says 71-90 lbs — a one-pound spread at the bottom of the band. At 48 inches, MidWest and Frisco both say 91-110 lbs while Precision extends to 90-125 lbs. So for a large adult dog, any of these charts lands you in roughly the same box. For a puppy or a mid-size breed, the brand you consult moves the answer by a whole size, and the only chart that counts is the one on the page of the crate you are buying.

What “42-inch” is actually measuring

The size designation is the crate’s length. Diggs publishes both an interior and an exterior set for the Small, Medium, Intermediate and Large Revol; on the Medium that is 31.4 x 20.6 x 21.5 in inside and 34.6 x 22.9 x 23.8 in outside. That is 3.2 in of length and 2.3 in each of width and height sitting in the structure. IRIS labels its number explicitly as exterior for the Large Deluxe.

That matters at the edges of a fit. The IRIS Large is longer than any 42-inch crate here, but it does not stand as tall as the wire crates from MidWest, Carlson and Precision. A dog that fits the floor of one does not have the same headroom in the other.

The divider is what decides whether you buy once

For a puppy, this is the whole purchase. Buy for the adult weight and the crate is a large open box on day one; buy for the current weight and it is outgrown in months. The divider is the mechanism that resolves that, and it either ships with your exact SKU or it does not.

MidWest includes it on every size in the iCrate single-door line and frames it as taking the crate from puppy kennel to full-size crate. EliteField includes it across all five sizes — the line is named 2-Door Dog Crate/Divider. Frisco includes one described as removable as the pup grows. Diggs includes a puppy divider with the Medium Revol for adjusting interior sizing during growth phases, though it does not publish whether the Intermediate and Large sizes ship with one.

Three picks here have no published divider for the configuration listed: Carlson’s Large single-door, Precision’s 42-inch one-door, and the IRIS Large Deluxe. Carlson’s case is the one to learn from, because the difference is not the size. Its Large double-door crate is listed with an adjustable divider to grow with your puppy; the Large single-door model #6005, at the same size, is not. Same brand, same footprint, different contents, different ASIN.

Doors change where the crate can live

A single front-facing door fixes the crate’s orientation — the front has to face into open floor. MidWest, Carlson and Precision are all single front-door on the ASINs here. Diggs uses one garage-style side door. Frisco has a front and a side door with dual latches on the larger sizes, and EliteField has front and side doors each with a self-locking slide-bolt, which lets either crate sit in a corner and still be loaded from the accessible side.

Two of the single-door picks have two-door siblings. Precision’s is fully documented — model 1127-11275FD, ASIN B003C5LJCS, 42 x 28 x 30 in, 70-90 lbs — so if the side door matters you can move to it without leaving the weight band. MidWest sells a 42-inch double-door iCrate as a separate ASIN, but does not publish its assembled dimensions.

Hardware you can actually compare

Only EliteField puts a number on the wire, quoting gauge by frame section. Every other crate names a latch and leaves the wire unquantified: MidWest a slide-bolt with a Locking Tip and patented Paw Block, Precision a 5-Point Locking System securing the door at five points along the frame, Carlson a multi-point door locking system, IRIS a front-door pin-lock with wire described only as heavy-gauge epoxy-coated steel, Frisco dual latches on larger sizes over an electro-coat finish. Diggs is outside the comparison entirely — a high-strength steel frame with diamond-shaped aluminum mesh panels and a dual-latch, two-step escape-prevention system, where wire gauge does not apply.

A named latch mechanism is checkable evidence. “Heavy-duty” without a gauge number is not, and there is no way to close that gap from the outside.

Weight, folding and moving it around

Published crate weights cluster tightly: Diggs Medium at 32 lbs, MidWest 42-inch at about 33.9 lbs, Precision 42-inch at roughly 33-34.4 lbs, IRIS Large at 35 lbs — a 3 lb spread across four crates. Frisco, EliteField and Carlson publish no crate weight at all.

Collapsed dimensions are almost entirely missing. Diggs publishes them for the Small Revol at 33 x 20 x 10 in and for no other size; no other brand here publishes them for any size. So “folds flat in seconds” from MidWest and EliteField, and “folds nearly flat” from Carlson, are descriptions of a design with no figure behind them. If storage footprint is a constraint, no listing in this set will settle it. Diggs adds built-in wheels and a carry handle, and Frisco adjustable carry handles, which are the only published aids to moving a crate between rooms.

When the plainer crate is enough

If the dog is full grown and you have a weight, a single-door wire crate with a published band does the entire job. MidWest and Precision both give you a chart, a named latch and a published crate weight, and the divider becomes irrelevant once the dog has stopped growing. Two doors are a convenience about placement, not about fit.

If you are buying for a puppy, that changes. The divider is the difference between one crate and several, so the SKUs that publish it across the whole size run — MidWest and EliteField — are doing something the others are not.

If your dog’s proportions are unusual, weight bands can misplace it in either direction, and Carlson’s method of stating pet length and height limits is the one approach here you can check with a tape measure.

And if the dog is heading past 110 lbs, the field narrows. MidWest, Frisco, EliteField and Precision all publish a 48-inch size, and Precision’s band reaches 90-125 lbs. The IRIS Deluxe wire line offers only Medium (35.4 x 23.6 x 21.7 in) and Large, so it does not scale up at all.

The thing nobody checks before ordering

A nominal size is shared across SKUs; the contents are not. Within a single brand and a single size you can find a single-door version and a double-door version at separate ASINs, with different latch counts and — as at Carlson — a divider in one and not the other. Confirm the door count and the divider on the exact listing you are ordering, not on the product line’s overview page. The size name will be identical either way.