Arc Length Calculator

Arc Length Calculator

Easily calculate arc length, sector area, and visualize circular segments with our free, accurate online tool. Perfect for students, engineers, designers, and math enthusiasts.

Using:
Quick angles:

Arc Length

7.853982
25.000000% of full circumference

Calculation Steps

Arc length formula: s = r × θ (θ in radians)

Angle conversion: 90° × (π/180) = 1.570796 radians

Calculation: 5 × 1.570796 = 7.853982

Arc Visualization

Arc Length: 7.854 m
Angle: 90°

What is Arc Length?

Arc length is the distance along the curved line that makes up a segment of a circle’s circumference. It’s an important concept in geometry, trigonometry, and many practical applications such as engineering, architecture, and design.

When you have a circle and a central angle (an angle whose vertex is at the center of the circle), the arc length is the portion of the circle’s circumference that corresponds to that angle. The relationship between arc length, radius, and angle is fundamental to circular geometry.

Arc Length Formula

The formula for calculating arc length depends on whether the angle is measured in degrees or radians:

For angles in radians:

s = r × θ

Where:

  • s = arc length
  • r = radius of the circle
  • θ = central angle in radians

For angles in degrees:

s = (θ/360) × 2πr

Or equivalently:

s = (πrθ)/180

Where:

  • s = arc length
  • r = radius of the circle
  • θ = central angle in degrees
  • π = mathematical constant pi (approximately 3.14159)

Practical Applications of Arc Length

Engineering & Construction

Arc length calculations are essential in designing curved structures, arches, bridges, and circular components in machinery.

Navigation

In navigation, arc length helps calculate distances along the Earth’s surface, which is approximately spherical.

Computer Graphics

Arc length is used in rendering curved shapes, animations, and designing user interface elements.

Manufacturing

In manufacturing, arc length calculations help determine material requirements for curved components.

Frequently Asked Questions

What’s the difference between arc length and chord length?

Arc length is the distance along the curved portion of a circle between two points, while chord length is the straight-line distance between those same two points.

Can arc length be greater than the circumference?

No, arc length is always a portion of the circumference, so it cannot exceed the total circumference of the circle.

How do I convert between degrees and radians?

To convert degrees to radians, multiply by π/180. To convert radians to degrees, multiply by 180/π.

What is sector area and how is it related to arc length?

Sector area is the area of the portion of a circle enclosed by two radii and their intercepted arc. While arc length measures the curved distance, sector area measures the space inside that curved segment.

Arc Length Formula & Explanation

The arc length s of a circle is calculated using the formula:

s = r × θ

Where:

  • r is the radius of the circle
  • θ is the central angle in radians

If the angle is in degrees, convert it to radians first:

θ (radians) = θ (degrees) × (π/180)

The percentage of the full circumference is:

Percentage = (θ / 360°) × 100%

The sector area is calculated as:

A = (θ/360°) × πr²


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