90 degrees to radians
1.5708 rad
90° = 1.5708 rad.
radians
1.5708rad
90° = 1.5708 rad
In short
How many radians is 90 degrees?
90° = 1.5708 rad. 1 degree = 0.017453 radians, so the working is 90 × 0.017453 = 1.5708.
The working
The factor below is an exact definition rather than a measurement, so nothing is approximated in the arithmetic. The only rounding on this page happens where a number is displayed.
1 degree = 0.017453 radians 90 × 0.017453 = 1.5708
How much precision do you need?
Each row is the same answer cut at a different number of decimals, with what that choice costs you. Pick the shortest row whose error is smaller than whatever you are measuring with.
| Rounded to | Answer (rad) | Off by |
|---|---|---|
| Whole number | 2 | +0.42920 |
| 1 decimal | 1.6 | +0.02920 |
| 2 decimals | 1.57 | −0.00080 |
Round trip: take 1.5708 rad back the other way and you land on 90.0002° — a drift of 0.0002°. That gap is the rounding, not the conversion.
What 90 ° looks like
90 °
A right angle, π/2 in radians, and the quarter turn that defines perpendicular in every branch of geometry.
Frequently asked questions
What is 90 degrees in radians?
90 degrees is 1.5708 radians. 1 degree = 0.017453 radians, so the working is 90 × 0.017453 = 1.5708.
How accurate is 1.5708 rad?
Rounding to 1.5708 rad and converting straight back gives 90.0002°, a drift of 0.0002° from the 90 you started with. The factor itself is exact; every bit of that difference comes from the rounding, not the conversion.
Nearby values
Any value at all
Degrees to Radians Converter
Convert degrees to radians — trigonometry, calculus, and anything using π.
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