Gusset Plate Calculator
This gusset plate calculator estimates the tension capacity of a steel gusset plate governed by yielding on the gross section, the first limit state checked when a connection plate carries an axial pull. A gusset plate ties members together at a joint in a truss or brace, and one of the ways it can fail is by stretching and yielding across its full width. The capacity for that limit state is the resistance factor times the yield strength times the gross cross-sectional area, where the gross area is simply the plate width times its thickness. This is the standard gross-section yielding check used throughout steel design and in the structural assessments behind transportation infrastructure overseen by agencies such as the US National Highway Traffic Safety Administration. Enter the plate width, the plate thickness and the steel yield strength, and the calculator returns the gross area and the design tension capacity, using a resistance factor of 0.90. Use it to size a gusset, check an existing connection, or teach the limit-state method. Every figure is computed deterministically from the yielding formula shown in full below, with a worked example that reconciles exactly to the calculator so you can follow each step yourself.
Gross-section yield capacity is the factored yield stress times the gross area: a 8 in wide, 0.5 in thick plate of 36 ksi steel has a gross area of 4.00 square inches and a design tension capacity of 129.60 kips (with a 0.90 factor).
Gusset plate gross-yield formula
Ag = w x t
design capacity = phi x Fy x Ag, with phi = 0.90
w = plate width, t = plate thickness
Fy = steel yield strength, Ag = gross cross-sectional area
Yielding on the gross section is one of the limit states for a plate in tension. The gross area is width times thickness, the nominal capacity is the yield stress times that area, and a resistance factor of 0.90 reduces it to a design value. Block shear and net-section rupture are separate checks not covered here.
Worked example
Find the tension capacity of an 8 inch wide, 0.5 inch thick plate of 36 ksi steel.
- gross area Ag = 8 x 0.5 = 4.00 square inches
- nominal yield = Fy x Ag = 36 x 4.00 = 144.00 kips
- apply resistance factor: 0.90 x 144.00 = 129.60 kips
The design tension capacity is 129.60 kips for gross-section yielding. These are the calculator's default inputs, so the result above matches the widget exactly.
Capacity by thickness for an 8 inch plate
With 36 ksi steel and a 0.90 factor, thicker plate carries proportionally more tension.
| Thickness (in) | Ag (sq in) | Capacity (kips) |
|---|---|---|
| 0.25 | 2.00 | 64.80 |
| 0.375 | 3.00 | 97.20 |
| 0.50 | 4.00 | 129.60 |
| 0.75 | 6.00 | 194.40 |
Structural and transportation safety context: US National Highway Traffic Safety Administration (NHTSA).
Gusset Plate Calculator: frequently asked questions
What limit state does this check?
It checks tension yielding on the gross section, where the whole width of the plate stretches and yields. The design capacity is the resistance factor of 0.90 times the yield strength times the gross area. A complete gusset design also checks net-section rupture at the bolt holes and block shear, which can govern and are separate calculations.
Why is the resistance factor 0.90?
Steel design assigns a resistance factor to each limit state to account for material and fabrication uncertainty. Gross-section yielding uses 0.90 because yielding is a ductile, well-understood failure that gives ample warning. Rupture limit states use a lower factor of 0.75 because fracture is more sudden and less forgiving.
What yield strength should I use?
Use the specified minimum yield strength of the steel grade. Common structural plate is 36 ksi for older A36 steel or 50 ksi for modern A572 grade 50. Enter the value for your material; the capacity scales directly with it, so a 50 ksi plate of the same size carries about 39 percent more load.
Does this include the bolt holes?
No. The gross-section yielding check uses the full plate area with no deductions. The reduction for bolt holes belongs to the net-section rupture check, where you subtract the hole area and apply the 0.75 factor with the tensile strength. Both checks should be performed, and the smaller capacity governs.
What units does it use?
It works in US customary structural units: inches for width and thickness, ksi (kips per square inch) for yield strength, and kips for the resulting capacity. One kip is one thousand pounds. Keep all inputs in these units so the area comes out in square inches and the capacity in kips.
Official sources
- Vehicle and transportation structural safety reference: US National Highway Traffic Safety Administration (NHTSA). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.