🔵 Radius Corner Calculator (Fillet)
Calculate fillet (rounded corner) geometry from radius, chord, arc length, sagitta or angle. Visualize the arc, get sector/segment area, and export SVG. Units: mm/cm/in/px.
Select Input Mode
Select Input Mode
Input Values
Select Unit
Visualization
Use Cases
- •CAD Design
- •Mechanical Engineering
- •Woodworking
- •Laser Cutting
- •3D Printing
- •UI/UX Design
Frequently Asked Questions
Common questions about radius corner calculations and our calculator.
How do I calculate corner radius from chord length?
Use the formula: r = c / (2 × sin(θ/2)), where c is the chord length and θ is the angle in radians. For 90° corners, this simplifies to r = c / √2.
What is sagitta and how is it calculated?
Sagitta is the maximum distance from the chord to the arc. It's calculated as s = r × (1 - cos(θ/2)), where r is the radius and θ is the angle.
How to get arc length from radius and angle?
Arc length is calculated as L = r × θ, where r is the radius and θ is the angle in radians. To convert degrees to radians, multiply by π/180.
Key Formulas
Complete Guide to Radius Corner Calculations
Learn everything about radius corners, fillets, and geometric calculations with detailed explanations and real-world examples.
Read Complete GuideA radius corner calculator (also known as fillet calculator) is an essential tool for CAD designers, mechanical engineers, woodworkers, laser cutting professionals, 3D printing enthusiasts, and UI/UX designers. This comprehensive calculator supports multiple input modes to calculate fillet geometry parameters from radius, chord length, arc length, sagitta, or diagonal cut measurements.
Key Features
Our radius corner calculator offers comprehensive functionality for all your fillet calculation needs.
Calculation Methods
Explore all five different methods to calculate radius corner geometry. Each method is suitable for different scenarios based on the information you have.
Known Radius
Wikipedia - Circular ArcCalculate all geometric parameters when you know the radius and angle. This is the most direct method and serves as the foundation for other calculations.
L = r × θ, c = 2r × sin(θ/2), s = r × (1 - cos(θ/2))Variables:
Use Case:
When you have the radius and angle measurements
Graphic Description:
Corner showing radius r and angle θ
Known Chord Length
Math Open Reference - ChordCalculate from chord length (straight-line distance between endpoints) and angle. Useful when you can measure the straight distance but not the radius directly.
r = c / (2 × sin(θ/2))Variables:
Use Case:
When you have chord length and angle
Graphic Description:
Corner showing chord c and angle θ
Known Arc Length
Math Open Reference - Arc LengthCalculate from arc length (circumference of the arc) and angle. Perfect when you can measure the curved distance along the arc.
r = L / θ (where θ is in radians)Variables:
Use Case:
When you have arc length and angle
Graphic Description:
Corner showing arc length L and angle θ
Known Sagitta (Arc Height)
Wikipedia - SagittaCalculate from sagitta (maximum distance from chord to arc) and angle. Useful when you can measure the "bulge" height of the arc.
r = s / (1 - cos(θ/2))Variables:
Use Case:
When you have sagitta and angle
Graphic Description:
Corner showing sagitta s and angle θ
Diagonal Cut (90° Only)
Engineering Toolbox - Fillet WeldingCalculate from diagonal cut length for 90-degree corners. This method is specific to right-angle fillets and uses the 45-degree diagonal measurement.
r = d / (1 + √2/2)Variables:
Use Case:
For 90-degree corners with diagonal cut measurement
Graphic Description:
Right-angle corner showing diagonal cut d
How to Use the Radius Corner Calculator
Follow these simple steps to calculate radius corner geometry using our comprehensive calculator.
1. Select Input Mode
Choose the calculation method that matches the information you have about your corner. Options include known radius, chord length, arc length, sagitta, or diagonal cut.
2. Choose Units
Select your preferred unit of measurement from millimeters, centimeters, inches, or pixels.
3. Enter Values
Input the known values for your corner. The required fields will change based on your selected calculation method.
4. View Results
The calculator will automatically compute all geometric parameters and display the results with comprehensive measurements.
5. Visualize Geometry
View the SVG visualization showing your corner with all key dimensions annotated for better understanding.
6. Export SVG
Download the SVG visualization for use in your design software or documentation.
Tips for Accurate Calculations
Follow these tips to ensure accurate radius corner calculations.
Frequently Asked Questions
Common questions about radius corner calculations and our calculator.