Ordering the wrong stud depth on a multifamily job does not delay one wall. It backs up drywall, mechanical, electrical, and plumbing (MEP) rough-in, and every trade behind them. Reordering burns days, and the whole mistake usually traces back to a spec misread at submittal.
Metal stud sizes follow a standardized designation system, but the naming trips up even seasoned pros. Web depth, flange width, and material thickness each mean something specific in a callout, and it is easy to confuse gauge with mils, or design thickness with nominal size. That confusion is where most ordering errors start.
This guide breaks down the cold-formed steel (CFS) sizing system: how to read a callout, what the standard dimensions mean, and which field conditions force a heavier member than the drawings first assumed.
Read the Label Right Before You Order the Wrong Stud
Every CFS member carries a printed designation. It is not random. It encodes four facts in sequence, and misreading one puts the wrong steel on the truck.
How a Callout Encodes Depth, Type, and Flange
A CFS callout follows one pattern: web depth in hundredths of an inch, then a member-type letter, then flange width in hundredths of an inch. The letter flags the section: S for stud, T for track, J for joist, U for channel.
So 600S162 reads as a 6-inch web, stud, with a 1-5/8-inch flange. 362S125 is a 3-5/8-inch stud with a 1-1/4-inch flange. Depth drives load capacity; flange width drives fastener edge distance and panel rigidity. You cannot swap one for the other in the field.
Why Gauge, Mils, and Design Thickness Differ
Gauge is a nominal label. Mils is the actual base-metal thickness in thousandths of an inch. Design thickness is the slightly lower number used in load calculations, which accounts for manufacturing tolerance.
The cold-formed steel product dimensions and thicknesses reference is clear on the conversions: 20 gauge is 33 mils, and 16 gauge is 54 mils. If the engineer called for 54 mil, confirm 54 mil, whatever the gauge label reads. The number after a hyphen in a callout, as in 600S162-54, is that design thickness in mils.
The Metal Stud Sizes Chart Contractors Need on Bid Day
Most estimators keep a mental list of standard sizes. That list usually misses the outliers: tall walls, heavy loads, and specialty assemblies.
Web Depths From 1-5/8 Inch to 12 Inch
Web depth sets wall thickness, insulation cavity, and structural strength.
| Prefix | Web Depth | Common Applications |
|---|---|---|
| 162 | 1-5/8 in. | Shaft walls, furring, light partitions |
| 250 | 2-1/2 in. | Interior partitions, low walls |
| 362 | 3-5/8 in. | Standard interior and exterior walls |
| 400 | 4 in. | Exterior walls with added insulation depth |
| 550 | 5-1/2 in. | Taller exterior walls, energy compliance |
| 600 | 6 in. | Structural exterior walls, tall partitions |
| 800 | 8 in. | High-load bearing, multi-story |
Most residential and light commercial work stays with 362 and 600 depths. Tall buildings or big wind loads move you to 800 and up.
Flange Widths and Gauge Ranges
Flange width sets the bearing surface for sheathing and drywall. The two common widths are 1-1/4 inch (125) and 1-5/8 inch (162); the wider 162 flange gives more fastener edge distance and suits structural and exterior walls. Gauge then follows the load:
- 25 Ga. (18 mil): non-structural partitions, low interior walls
- 20 Ga. (33 mil): standard load-bearing walls
- 18 Ga. (43 mil): heavier or taller load-bearing
- 16 Ga. (54 mil): high-load structural, multi-story bearing, headers
- 14 Ga. (68 mil): heavy structural, transfer beams
The Field Conditions That Turn a Light Spec Into a Reorder
A spec can pass a first review and still come up short once real loads and heights are in play. These are the usual triggers for a heavier member.
Deflection, Wind, and Wall Height
Deflection is movement under load. Walls with tile or stucco usually hold to L/360, meaning height divided by 360, while drywall-only walls often accept L/240. Wind load in Texas, Oklahoma, and the Gulf Coast can push a stud deeper or heavier than vertical load alone would.
A 3-5/8-inch, 20-gauge stud may carry a two-story wall vertically yet fail deflection under 120-mph wind. The nonstructural steel stud height limits tables give allowable heights by depth, gauge, and spacing.
Spacing, Coatings, and Top-of-Wall Movement
Stud spacing sets allowable height for a given size, so the same stud at 24 inches on center reaches less height than at 16. Galvanized coating class follows exposure: G40 or G60 for interior partitions, G90 for exterior and coastal walls.
And at the head of a non-load-bearing exterior wall, slotted deflection track lets the stud float as the structure above moves, so a non-structural stud never carries load it was not sized for. Each of these belongs in the spec before fabrication, not the field.
For the full range of profiles and gauges available to spec against, see this reference on cold-formed steel stud sizes.
Get the Framing Package Right While the Schedule Still Moves
Stud selection is not a one-time estimate call. It shapes every trade downstream, from MEP rough-in to drywall to final inspection. Confirming size, flange, gauge, and coating before fabrication is the surest way to hold both schedule and budget.
If you are spec’ing framing for a mid-rise, strip center, or podium build in the south-central US, lock the designations down before the coil hits the machine. Call Symmtrex at (469) 842-7794 or get a fabrication estimate on your framing package.
Frequently Asked Questions
How Do You Read a Metal Stud Size Code Like 600S162?
Read it in three parts: web depth in hundredths of an inch, a member-type letter, then flange width in hundredths. So 600S162 is a 6-inch stud with a 1-5/8-inch flange. A number after a hyphen, like -54, is the design thickness in mils.
What’s the Difference Between Gauge, Mils, and Design Thickness?
Gauge is a nominal label, mils is the actual base-metal thickness, and design thickness is the slightly lower figure used in load calculations. Spec and confirm by mils, since 20 gauge is 33 mils and 16 gauge is 54 mils.
What Stud Depth Do You Need for a Given Finished Wall Thickness?
Take the finished wall thickness and subtract the board on each face. A 3-5/8-inch stud with 5/8-inch drywall on both sides finishes at about 4-7/8 inches. That number drives door frames, window sills, and box alignment.
Which Gauge Should a Non-Load-Bearing Partition Use?
Start at 25 gauge for low partitions and step up to 20 gauge as walls get taller. Run the limiting-height table for your depth, gauge, and spacing rather than defaulting to one gauge across the whole job.
When Does a Wall Need Deflection (Slotted) Track?
At the head of a non-load-bearing exterior wall in a multi-story building, where the structure above flexes. Slotted deflection track lets the stud slide vertically while still taking lateral load, which keeps that movement out of finishes.