By using this website, you agree to our Cookie Policy. The following equation describes the relation between the circumference and the radius R of a circle: Where π is a constant approximately equal to 3.14159265... A similarly simple formula determines the relationship between the area of a circle and its radius: If you wish to calculate the properties of a three-dimensional solid, such as a sphere, cylinder or cone, it's best to use our volume calculator. You can use our circumference calculator as circumference to diameter calculator. This is typically written as C = πd. Given the radius of a circle calculate the area, circumference and diameter. Calculate A, C and r | Given d Starting from the diameter, you can easily find the other two. √ = square root. Circumference is often misspelled as circumfrence. With any of these variables (A, C, r or d) of a circle, you can precisely measure the other three unknowns. A = area of the circle. If you prefer a numerical value, the answer rounded to the nearest tenth is 37.7 cm. If you want to draw a circle on the Cartesian plane, you might find this equation of a circle calculator useful. Calculate A, C and d | Given r Given the radius of a circle calculate the area, circumference and diameter. (a non-terminating value) For easier computation of the circumference of a circle, the value of pi is taken to be 3.14 (π = 3.14). This calculator can find the center and radius of a circle given its equation in standard or general form. Using the circumference formula to find the diameter of a circle. The circumference of a circle is calculated using the formula: 2 x π x radius, where π is a mathematical constant, equal to about 3.14159. The formula to find the circumference when radius is given is Radius = Circumference/(2*π) The formula to find the area when radius is given is Area of circle = π*Radius*Radius In the above formulas, π=3.14159 and R is the radius. If you know the circle’s radius: d = 2r If you don’t know the radius or area: d = c / π If you don’t know the radius or circumference: d = 2√ ( a / π ) How to Find the Area of a Circle using a Circle Calculator: Find A The ‘a’ in any circle formula stands for the area of the circle. Just input the circumference value in the input field and the diameter of a circle from circumference calculator will automatically update you with the circle diameter. Putting A, r and d in terms of C the equations are: \[A = \pi r^2 = \pi \left(\frac{C}{2 \pi}\right)^2 = \frac{\pi C^2}{4 \pi^2} = \frac{C^2}{4 \pi} \], \[d = 2r = \frac{2C}{2 \pi} = \frac{C}{\pi} \]. The diameter of a circle will be shown in the selected units. ), radius to area, diameter to circumference, diameter to radius (yes, again with the rocket science), diameter to area, area to circumference, area to diameter or area to radius. r = radius, d = diameter. The circumference of a semicircle is not equal to half of the circle circumference - you need to add also the diameter of the semicircle, as another boundary was created: Perimeter semicircle = (circumference circle / 2) + 2 * radius. You’ve been asked to calculate the circumference of a circle, you measure the diameter and find it is 2m. Substitute this value to the formula for circumference: You can also use it to find the area of a circle: Finally, you can find the diameter - it is simply double the radius: Use our circumference calculator to find the radius when you only have the circumference or area of a circle. It is used in many areas, such as physics and mathematics. Read on to learn: As is the case with all of our tools, the circumference calculator works in all directions - it is also a circumference to diameter calculator, and can be used to convert circumference to radius, circumference to area, radius to circumference, radius to diameter (duh! Circumference/Diameter = Pi. C = 6.28m They do not affect the calculations. Free Circle calculator - Calculate circle area, center, radius and circumference step-by-step This website uses cookies to ensure you get the best experience. A circle is a shape with all points at the boundary having the same distance to the centre. Circumference of a circle: C = 2 π r = π d. Circle Calculations: Using the formulas above and additional formulas you can calculate properties of a given circle for any given variable. The approximate value of pi (π) = 22/7 = 3.1415926535897…. Radius (r) = Diameter (D) ÷ 2. r = 2m ÷ 2 . Given any one variable A, C, r or d of a circle you can calculate the other three unknowns. This shows us that the circumference of the circle is three “and a little” times as long as the diameter. Here’s the algorithm: Input the radius of the circle from the user. The equation for diameter of a circle from circumference is: d … What is Pi? Substitute this value to the formula for circumference: C = 2 * π * R = 2 * π * 14 = 87.9646 cm. Then calculate the circumference (C) C = 2 x π x r. C = 2 x 3.14 x 1m. If you know radius and angle you may use the following formulas to calculate remaining segment parameters: The value of this ratio is 3.14156. 28.27 = 18.85 (*) (*) 18.85 cm exactly or limited to de precision of this calculator (13 decimal places). All rights reserved. Here circum indicates to circumference value, π indicates to 3.14 and r indicates to the radius of circle.. r = 1m. This depends on whether or not you know the radius ( r) or the diameter ( d) Let’s calculate one manually, for example. Cite this content, page or calculator as: Furey, Edward "Circle Calculator"; CalculatorSoup, Super easy in place to give an indication of the diameter is 6 feet across units of for... Plane, you can easily find the other two this calculator can find in! 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