Introduction
This Pi Calculator helps you do math with π (pi) fast. Pi is about 3.14159, and it shows up in circles, angles, waves, and lots of geometry problems. Instead of typing 3.14 by hand, just tap the π key and get a full-precision answer.
You can add, subtract, multiply, divide, and use powers. Open the Advanced panel for square roots, nth roots, sine, cosine, tangent, logs, and e. Switch between radians (RAD) and degrees (DEG) with one tap, and pick how many decimal places you want to see.
Every answer comes with a step-by-step solution, so you can see how the math works, not just the final number. The Result Details box also shows your answer as a multiple of π, in degrees, in radians, and in scientific notation. A chart compares your result to common pi values like π, 2π, π/2, and π². Your last 20 calculations are saved in the history list, and you can click any of them to use it again.
How to use our Pi Calculator
Type a math problem that uses pi, then read the answer. The calculator shows your result, extra details, a step-by-step solution, and a chart that compares your answer to common pi values.
Number and operator keys: Tap the digits 0–9, the decimal point, and the signs +, −, ×, ÷, or ^ to build your problem.
π key: Tap the big purple π button to add pi (3.14159…) to your expression.
Angle mode (RAD or DEG): Pick RAD if your angles are in radians, or DEG if they are in degrees. This changes answers for sin, cos, and tan.
Result precision: Choose how many decimal places you want to see, or leave it on Auto for 10 significant digits.
Advanced button: Tap Advanced to open extra science keys like square root, nth root, powers, logs, e, and inverse trig functions such as arcsin and tan inverse.
( ) and (−) keys: Use the bracket key to group parts of your problem, and the (−) key to make the last value negative.
AC and DEL keys: Press DEL to erase one entry, or AC to clear everything and start over.
= or Calculate button: Press either one to solve your problem and save it to your history.
Copy button: Tap Copy to put the answer on your clipboard so you can paste it somewhere else.
Calculation History: Tap any past problem to load it back into the calculator, or press Clear History to empty the list.
Reset button: Press Reset to return to the sample problem and the default settings.
Keyboard: You can also type numbers and operators, press P for pi, E for e, Enter to solve, Backspace to delete, and Esc to clear.
What Is Pi (π)?
Pi is a number that shows up in every circle. If you measure the distance around a circle (the circumference) and divide it by the distance across it (the diameter), you always get pi. It does not matter if the circle is a coin or a planet. The answer is the same.
Pi starts like this: 3.14159265358979... The digits never end and never repeat in a pattern. That makes pi an irrational number. Because it never ends, we round it. Most school work uses 3.14 or the fraction 22/7. Engineers and scientists often use more digits, like 3.14159265.
Formulas That Use Pi
- Circumference of a circle: C = 2πr or C = πd
- Area of a circle: A = πr²
- Volume of a cylinder: V = πr²h
- Volume of a sphere: V = (4/3)πr³
- Surface area of a sphere: A = 4πr²
- Volume of a cone: V = (1/3)πr²h
In these formulas, r is the radius (half the width of the circle) and h is the height.
Pi and Angles
Pi is also used to measure angles in radians. A full turn around a circle is 2π radians, which equals 360°. So half a turn is π radians (180°), and a quarter turn is π/2 radians (90°). To change radians into degrees, multiply by 180/π. To change degrees into radians, multiply by π/180. This matters when you use sine, cosine, and tangent, since the answer changes based on whether you work in radians (RAD) or degrees (DEG).
Handy Pi Values
- π ≈ 3.141592654
- 2π ≈ 6.283185307
- π/2 ≈ 1.570796327
- π/4 ≈ 0.785398163
- π² ≈ 9.869604401
- 1/π ≈ 0.318309886
Where Pi Is Used
Pi is not just for math class. It helps people find the size of pipes and wheels, build round tanks, plan gears and engines, track waves and sound, and figure out orbits in space. Even game builders use it. Any time something spins, curves, or repeats, pi is usually part of the math.
A Little History
People have studied pi for thousands of years. Ancient Babylonians and Egyptians used rough values close to 3.125 and 3.16. Around 250 BC, the Greek thinker Archimedes drew shapes inside and outside a circle to prove pi sits between 3⅞₁ and 3⅝. The Greek letter π became the common symbol in the 1700s, thanks in part to the mathematician Leonhard Euler. Today, computers have found trillions of digits of pi, but for almost all real work, a few digits are plenty.