Does my data get uploaded anywhere?
No. Everything runs locally in your browser and nothing is sent to a server.
Is this free to use?
Yes. It is completely free, with no account, no signup, and no usage limits.
Does it work on a phone?
Yes. The page runs in any modern mobile browser, on iPhone and Android alike, with no app to install.
How many radians is 90 degrees?
1.5707963268 radians, which is pi/2. The full set is worth memorising: 90 degrees is pi/2, 180 degrees is pi (3.14159265359), and 360 degrees is 2 pi (6.28318530718).
What is a gradian?
A gradian, or gon, divides a full turn into 400 parts instead of 360, so a right angle is exactly 100 gradians. It survives in European surveying and on some scientific calculators, and 1 gradian is 0.9 degrees exactly.
Can I paste coordinates like 40 26 46?
Not as a single string. Convert them first: divide the minutes by 60, the seconds by 3,600, and add them to the degrees, so 40 degrees 26 minutes 46 seconds becomes 40.446111 degrees. Then enter that number with Degree selected.
Why does Math.sin(90) not return 1 in my code?
Because the standard library expects radians, and 90 radians is over 14 full turns. Convert 90 degrees to 1.5707963268 radians and Math.sin returns 1. This is the single most common bug that sends people to an angle converter.
How many degrees is one radian?
57.2957795131 degrees, which is 180/pi. A radian is the angle subtended when the arc length equals the radius, so it is the natural unit for any calculation involving arc length or angular velocity.