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Metal Stud Gauges Explained: 25, 20, 18 Gauge and Beyond

What metal stud gauge means, common gauges and mil thicknesses, and how wall height, spacing and finishes decide which gauge a project needs.

By SCCI Drywall. Published 2026-10-22.

Key Takeaways

  • Gauge is steel thickness; the lower the number, the thicker the stud.
  • Thickness is now usually listed in mils, such as 18 mil for 25 gauge.
  • Lighter gauges suit standard interior partitions; heavier gauges handle tall walls, heavy finishes and structural loads.
  • Wall height, stud spacing, depth and allowable deflection decide the right stud.

Ask for metal studs and the first question is "what gauge?" Here's what the numbers mean and how framers choose the right one.

Gauge and Mils

Gauge describes the thickness of the steel. As with wire, the lower the gauge number, the thicker the material. Because gauge numbers don't map perfectly to exact thickness, manufacturers and specs now usually list the minimum base steel thickness in mils (thousandths of an inch). Common pairings include:

  • 25 gauge: about 18 mil, a light interior partition stud
  • 20 gauge (drywall): about 30 mil, a heavier interior partition stud
  • 20 gauge (structural): about 33 mil
  • 18 gauge: about 43 mil, a common structural starting point
  • 16, 14 and 12 gauge: about 54, 68 and 97 mil, for heavier structural framing

Some manufacturers also offer "equivalent" or EQ studs, made from thinner, higher-strength steel and designed to perform like a standard gauge. Always follow the specified product and its published limits.

Stud Depth

Studs come in several common depths, such as 1-5/8, 2-1/2, 3-5/8, 4 and 6 inches. Deeper studs are stiffer, so a taller wall may call for a deeper stud, a heavier gauge, closer spacing, or a combination.

What Decides the Gauge

  • Wall height: taller walls need stiffer framing.
  • Stud spacing: 16 inches on center is stiffer than 24 inches.
  • Deflection limit: walls with brittle finishes like tile or stone need stiffer framing than painted drywall.
  • Loads: cabinets, TVs, equipment, doors and handrails often need heavier studs or added framing at those spots.
  • Door frames: jambs at doors, especially heavy or frequently used doors, typically get heavier studs.
  • Structural loads: anything carrying floors, roofs or wind must be engineered. See load-bearing vs. non-load-bearing studs.

Manufacturers publish limiting-height tables that show the maximum wall height for each stud size, gauge, spacing and deflection limit. Framers and designers use those tables to select the stud.

Gauge and Drywall

Very light studs can flex when drywall is screwed on, especially near openings, which can lead to cracks at door corners. Heavier jamb studs, proper bracing and the right screws help the drywall stay flat and crack-free.

Gauge and Fire-Rated Walls

Fire-rated wall designs specify the framing as well as the board. If a listed design calls for a particular stud size or minimum thickness, that's part of the rating. See fire-rated drywall assemblies.

Metal Stud Framing in San Antonio

SCCI Drywall frames walls, soffits and ceilings with the right stud for each condition, then hangs and finishes the drywall. Call (210) 875-0280 to talk through your project.

Frequently Asked Questions

Is 20 gauge thicker than 25 gauge?

Yes. With metal studs, a lower gauge number means thicker steel.

What gauge metal studs are used for interior walls?

Interior partitions commonly use light gauges such as 25 or 20 gauge drywall studs, chosen based on wall height, spacing and what will hang on the wall.

What does mil mean for metal studs?

Mil is thousandths of an inch. Specs list minimum steel thickness in mils, such as 18 mil for a typical 25 gauge stud.

Contact SCCI Drywall

SCCI Drywall serves San Antonio and all of South Texas with drywall installation, drywall repair, remodeling, metal stud framing, light gauge framing and acoustical grid ceiling systems for residential and commercial projects.

Phone: (210) 875-0280

Email: sccidrywall@gmail.com

Hours: Monday through Friday, 7:00 AM to 6:00 PM

Request a free drywall quote