How do I find the area of a circle?

Use A = πr², where r is the radius. If you only know the diameter, halve it first (r = d/2). For example, a circle of radius 5 has area π·25 ≈ 78.54.

What is the circumference formula?

C = 2πr = πd. A circle with radius 5 has a circumference of 2π·5 ≈ 31.42.

Rearrange A = πr² to r = √(A/π). This calculator does it automatically when you choose 'Area' as the known value.

Kalkulator lingkaran gratis. Dari jari-jari, diameter, luas, atau keliling, hitung tiga ukuran lainnya dengan π presisi.

Hitung luas, keliling, diameter, atau jari-jari lingkaran.

d = 2 r, C = 2 π r, A = π r^{2}