Geometry

  • Circle Area from Diameter Calculator
    Find the area of a circle from its diameter instantly. Uses A = πd²/4. Also shows radius and circumference. Fast, free, and accurate.
  • Surface Area of a Rectangular Prism Calculator
    Calculate the surface area of a rectangular prism (cuboid) from its length, width, and height using A = 2(lw + lh + wh). Free and instant.
  • Surface Area of a Square Pyramid Calculator
    Calculate the total surface area of a square pyramid from its base edge and height. Includes base area, lateral area, and slant height instantly.
  • Surface Area of a Cone Calculator
    Calculate the total surface area of a cone from its base radius and height. Get base area, lateral area, slant height and total area instantly.
  • Volume to Weight Calculator
    Convert volume to weight (mass) using density. Enter volume in mL, L, m³ or gallons and density to get mass in kg, grams and pounds.
  • Wall Paint Surface Area Calculator
    Calculate the wall surface area of a room and the paint needed. Deducts doors and windows from the gross area to give net square feet and gallons.
  • Heron's Formula Area Calculator
    Find a triangle's area from its three side lengths using Heron's formula. Enter sides a, b, and c to get the area, semi-perimeter, and perimeter instantly.
  • Right Triangle Area Calculator
    Calculate the area of a right triangle from its two legs using A = ½·a·b. Also returns hypotenuse and perimeter instantly.
  • Regular Hexagon Area Calculator
    Calculate the area of a regular hexagon from its side length using A = (3√3/2)s². Also returns perimeter and apothem instantly.
  • Triangle Area Calculator
    Calculate the area of a triangle from its base and height using A = ½·b·h. Fast, free, and accurate for any unit of measurement.
  • Square Area Calculator
    Calculate the area of a square instantly with A = s². Enter the side length and get area, perimeter, and diagonal in seconds.
  • Circle Area Calculator
    Calculate the area of a circle instantly with A = πr². Enter the radius to get area, diameter, and circumference in seconds.
  • Pounds to Gallons Calculator (Water)
    Convert pounds of water to US gallons instantly. Enter the weight in pounds and get the volume using the standard 8.34 lb per gallon factor.
  • Slope Percentage to Degrees Calculator
    Convert a slope percentage (grade) to degrees instantly. Enter the percent grade and get the slope angle in degrees and radians.
  • Circle Area and Circumference Calculator
    Calculate a circle's area, circumference, radius, and diameter from any one known value using A = πr² and C = 2πr. Fast and accurate.
  • Water Tank Volume Calculator
    Calculate water tank capacity in liters, US & UK gallons, and cubic meters. Works for cylindrical and rectangular tanks using simple dimensions.
  • Triangle Classification Calculator
    Classify a triangle as acute, right, or obtuse from its three side lengths by comparing the square of the longest side to the sum of the other two squared.
  • SOHCAHTOA Calculator
    Free SOHCAHTOA calculator. Enter a right-triangle angle and one side to solve the opposite, adjacent, and hypotenuse plus sin, cos, and tan.
  • Law of Cosines Third Side Calculator
    Find the third side of a triangle from two sides and the included angle (SAS) using the Law of Cosines: c = √(a² + b² − 2ab·cos C).
  • Height of a Triangle from Area and Base Calculator
    Find the height of a triangle from its area and base length. Uses h = 2 × Area / base. Fast, free, and works with any units.
  • Roof Pitch Angle Calculator
    Calculate roof pitch angle in degrees from rise and run. Also gives x-in-12 pitch, slope length and slope percentage for any roof or ramp.
  • Radius from Diameter Calculator
    Find the radius of a circle from its diameter instantly. Enter any diameter and this calculator returns the radius using r = d/2.
  • Radius from Area Calculator
    Calculate the radius of a circle from its area using r = √(A/π). Also returns diameter and circumference instantly. Free online geometry tool.
  • Diameter from Circumference Calculator
    Find a circle's diameter from its circumference using d = C / π. Instantly get diameter, radius, and area for any circumference value.

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