How to use this sine calculator
- Type an angle into the main field — a plain number such as 30, an expression such as π/2, or a multiple of π such as 2π (the π button inserts the symbol).
- Pick the unit next to the field: ° for degrees (30° gives sin = 0.5) or rad for radians (π/2 rad gives sin = 1).
- Press Calculate. The result is sin(x) rounded to 8 decimal places, exactly the way the classic sin(x) calculator pages compute it.
- For unit-tagged expressions, use the sine expression box: type sin(30 deg) or sin(2 rad) and press Calculate.
- To go backwards, enter a sine value between -1 and 1 in the inverse sine calculator to get the angles whose sine is it — both solution families, e.g. 30°+360k and 150°+360k (k = ...,-2,-1,0,1,2,...).
The sine of an angle is the y-coordinate of the corresponding point on the unit circle, so sin(x) always lands between -1 and 1: sin(0°) = 0, sin(90°) = 1, sin(180°) = 0, sin(270°) = -1. The sine curve repeats every 360° (2π radians), and because sin(180° − x) = sin(x), every input strictly between -1 and 1 has two solution families in each cycle — for sin(x) = 0.5 those are 30°+360k and 150°+360k. Degrees and radians convert by the usual factor — an angle in degrees is multiplied by π/180 before the sine is taken.
Every calculation runs locally in your browser — nothing is uploaded, and no account or connection is involved. More math tools are in Math & Statistics.