📐 K-Factor Calculator
Calculate K-factor for sheet metal bending
Bend angle in degrees (typically 90°)
How to Use This Calculator
Select Calculation Type
Choose standard, neutral axis, or simplified formula. Standard formula is most commonly used for sheet metal bending.
Enter Inside Radius
Input inside radius (Ri) in inches. This is the radius of the bend on the inside of the material.
Enter Material Thickness
Input material thickness (t) in inches. Common sheet metal thicknesses: 0.062" (16 ga), 0.090" (14 ga), 0.125" (11 ga).
Enter Bend Angle and Calculate
Input bend angle in degrees (typically 90°). Click "Calculate K-Factor" to see K-factor, bend allowance, and neutral axis position.
Formula
Standard: K = (Ri + t/2) / t
Neutral Axis: K = (t - 2(Ri + t/2)) / t
Bend Allowance: BA = π × (Ri + K × t) × (angle / 180)
where: Ri = inside radius, t = material thickness, K = K-factor
Example 1: Standard Formula (Ri = 0.125", t = 0.062", angle = 90°)
Step 1: K = (Ri + t/2) / t = (0.125 + 0.062/2) / 0.062 = (0.125 + 0.031) / 0.062 = 2.516
Step 2: Neutral Axis = Ri + K × t = 0.125 + 2.516 × 0.062 = 0.281"
Step 3: Bend Allowance = π × (Ri + K × t) × (90/180) = π × 0.281 × 0.5 = 0.441"
Example 2: Simplified Formula (Ri = 0.125", t = 0.062")
Step 1: K = 0.5 × (1 + (Ri/t)) = 0.5 × (1 + (0.125/0.062)) = 0.5 × (1 + 2.016) = 1.508
About K-Factor Calculator
The K-Factor Calculator is an essential tool for sheet metal fabricators, mechanical engineers, and designers who need to calculate K-factor for sheet metal bending. This calculator implements standard K-factor formulas based on inside radius and material thickness, helping you determine bend allowance and neutral axis position for accurate sheet metal fabrication.
When to Use This Calculator
- Sheet Metal Design: Calculate K-factor for bend allowance calculations
- Fabrication Planning: Determine material requirements for bent parts
- Tooling Design: Calculate bend parameters for tooling design
- Accuracy Improvement: Improve bend accuracy by calculating correct K-factor
- Educational Use: Learn and understand K-factor calculations
Why Use Our Calculator?
- ✅ Multiple Formulas: Supports standard, neutral axis, and simplified formulas
- ✅ Accurate Calculations: Uses standard K-factor equations
- ✅ Complete Analysis: Shows K-factor, bend allowance, and neutral axis
- ✅ Easy to Use: Simple inputs for radius, thickness, and angle
- ✅ Time Savings: Instant calculations eliminate manual math
Understanding K-Factor
Basic Principle: K-factor (K) is a dimensionless value that represents the location of the neutral axis during sheet metal bending. The neutral axis is the line in the material that experiences no stretching or compression during bending. K-factor typically ranges from 0.3 to 0.5 for most materials, with 0.5 representing a perfect neutral axis at the center.
Bend Allowance: Bend allowance is the length of material required to make a bend. It's calculated using BA = π × (Ri + K × t) × (angle / 180), where Ri is inside radius, t is material thickness, and angle is bend angle in degrees. Accurate K-factor ensures correct bend allowance.
Material Properties: K-factor depends on material properties, thickness, and bend radius. Typically, K = 0.5 for thin materials or tight bends, and K decreases for thicker materials or larger bend radii. Actual K-factor may vary based on material properties and bending conditions.
Tips for Best Results
- Accurate Measurements: Measure inside radius and thickness accurately
- Use Standard Formula: Standard formula works well for most applications
- Consider Material: K-factor may vary by material (steel, aluminum, etc.)
- Verify with Testing: Test actual bend allowance and adjust K-factor if needed
- Check Bend Angle: Ensure correct bend angle for accurate calculations
Frequently Asked Questions
What is K-factor?
K-factor (K) is a dimensionless value that represents the location of the neutral axis during sheet metal bending. The neutral axis is the line in the material that experiences no stretching or compression. K-factor typically ranges from 0.3 to 0.5, with 0.5 representing a perfect neutral axis at the center of the material.
How do I calculate K-factor?
Standard formula: K = (Ri + t/2) / t, where Ri is inside radius and t is material thickness. For example, Ri = 0.125", t = 0.062": K = (0.125 + 0.062/2) / 0.062 = 2.516. The calculator does this automatically for standard, neutral axis, and simplified formulas.
What is a typical K-factor value?
K-factor typically ranges from 0.3 to 0.5 for most sheet metal materials. K = 0.5 represents a perfect neutral axis at the center, common for thin materials or tight bends. K decreases for thicker materials or larger bend radii. Actual K-factor depends on material properties and bending conditions.
What is bend allowance?
Bend allowance is the length of material required to make a bend. It's calculated using BA = π × (Ri + K × t) × (angle / 180), where Ri is inside radius, t is thickness, K is K-factor, and angle is bend angle in degrees. Accurate K-factor ensures correct bend allowance for material planning.
Does K-factor vary by material?
Yes, K-factor may vary by material properties (steel, aluminum, stainless steel, etc.), thickness, and bend radius. Typically, K = 0.5 for thin materials or tight bends, and K decreases for thicker materials or larger bend radii. Actual K-factor should be verified through testing for critical applications.