Geometry Tool

Curvature Calculator - Curve Curvature Calculator & Radius of Curvature Calculator

Free curvature calculator & curve curvature calculator. Calculate curvature κ (kappa), radius of curvature ρ (rho), and analyze how curves bend. Our calculator uses differential geometry formulas to determine curvature at any point for explicit functions, parametric curves, and circles.

Last updated: October 28, 2025

Calculate curvature and radius instantly
Support for multiple curve types
Step-by-step derivative calculations

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Curvature Calculator
Calculate the curvature of curves and functions

Enter functions like x², x³, sin(x), or cos(x)

Enter the x-coordinate where you want to calculate curvature

Curvature Analysis

Curvature (κ):

0.178885

Radius of Curvature (ρ):

5.590170

First Derivative:

f'(1) = 2.000

Second Derivative:

f''(1) = 2.000

Formula:

κ = |2.000| / (1 + 2.000²)^(3/2) = 0.178885

Interpretation:

Moderate curvature - parabolic curve

Curvature Concepts:

  • • Curvature measures how fast a curve changes direction
  • • Higher curvature = sharper bend (tighter turn)
  • • Lower curvature = gentler bend (wider turn)
  • • Radius of curvature ρ = 1/κ (reciprocal of curvature)
  • • For a circle: κ = 1/r (constant at all points)

Curvature Calculator Types & Applications

Curve Curvature Calculator
Calculate curvature for any mathematical curve or function

Supported curves

Explicit, Parametric, Polar

Analyzes curvature κ for various curve representations and coordinate systems

Radius of Curvature Calculator
Find the radius of the osculating circle at any point

Formula

ρ = 1/κ

Calculates the radius of the circle that best fits the curve at a point

Circle Curvature Calculator
Calculate constant curvature for circles of any radius

Circle formula

κ = 1/r

For circles, curvature is constant and inversely proportional to radius

Curvature of a Function Calculator
Calculate curvature for explicit functions y = f(x)

Formula

κ = |f''(x)| / (1 + (f'(x))²)^(3/2)

Uses first and second derivatives to calculate curvature at any point

Osculating Circle Calculator
Find the circle that best approximates a curve at a point

Properties

Same tangent & curvature

The osculating circle shares the curve's tangent and curvature at contact

Curvature at a Point Calculator
Evaluate curvature at specific points on a curve

Analysis

Point-specific κ

Calculate how sharply a curve bends at any specified location

Quick Example Result

For function f(x) = x² at point x = 1:

Curvature (κ)

0.358569

Radius (ρ)

2.788675

How Our Curvature Calculator Works

Our curvature calculator analyzes curves using differential geometry principles. The calculation applies derivative analysis to determine how rapidly a curve changes direction at any given point. Curvature κ (kappa) quantifies this rate of change, while radius of curvature ρ (rho) represents the osculating circle radius.

The Curvature Formula

κ = |f''(x)| / (1 + (f'(x))²)^(3/2)

This formula calculates curvature for explicit functions y = f(x) using the first derivative f'(x) (slope) and second derivative f''(x) (rate of slope change). The result measures how sharply the curve bends at point x.

📈 Curvature Visualization

Shows osculating circles and curvature values at different points

Mathematical Foundation

Curvature is a fundamental concept in differential geometry that measures the deviation of a curve from being a straight line. The curvature formula derives from the rate of change of the unit tangent vector with respect to arc length. For practical calculations, we use derivatives with respect to x rather than arc length, which gives us the formula above.

  • Higher curvature values indicate sharper bends (tighter curves)
  • Lower curvature values indicate gentler bends (wider curves)
  • Straight lines have zero curvature (κ = 0)
  • Circles have constant curvature equal to 1/radius
  • Radius of curvature ρ = 1/κ gives the osculating circle radius
  • The osculating circle is the best-fitting circle at a point

Sources & References

  • Differential Geometry of Curves and Surfaces - Manfredo P. do Carmo (2nd Edition)Comprehensive reference for curvature theory and applications
  • Calculus: Early Transcendentals - James Stewart (8th Edition)Standard calculus textbook covering curvature calculations
  • Wolfram MathWorld - CurvatureDetailed mathematical definitions and formulas for curvature

Need help with other calculus tools? Check out our derivative calculator and concavity calculator.

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Curvature Calculator Examples

Curve Curvature Calculator Example
Calculate curvature of f(x) = x² at point x = 1

Function Properties:

  • Function: f(x) = x²
  • Point: x = 1
  • f'(x): 2x → f'(1) = 2
  • f''(x): 2 → f''(1) = 2

Curvature Calculation Steps:

  1. Find f'(1) = 2
  2. Find f''(1) = 2
  3. Apply formula: κ = |2| / (1 + 2²)^(3/2)
  4. Calculate: κ = 2 / (5)^(3/2) ≈ 0.358569
  5. Find ρ = 1/κ ≈ 2.788675

Result: κ ≈ 0.358569, ρ ≈ 2.788675

Moderate curvature indicating a parabolic bend with osculating circle radius of 2.79 units.

Circle Curvature Example

Circle with radius r = 5

κ = 1/5 = 0.2 (constant everywhere)

Straight Line Example

f(x) = 2x + 1

κ = 0 (no curvature - straight)

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