Calcora
Free · No sign-up · Runs in your browser

A scientific calculator that keeps up with you

Type whole expressions the way you would write them, watch the answer update as you go, and switch between degrees and radians in one tap.

DEGAns = 0
0
 
Why Calcora

Built for homework, lab work and everything in between

Everything you expect from a handheld scientific calculator, with a screen big enough to see what you typed.

Type it as you'd write it

Write 2π(3+4) or √(3^2+4^2). Missing brackets close themselves and implied multiplication just works.

Live answer preview

A faint result updates under your expression as you type, so you spot mistakes before you press equals.

Degrees or radians

One button switches angle mode, and the display always shows which one you're in.

Reusable history

Your last twelve answers sit beside the keypad. Tap one, or use Ans, to carry a result forward.

Keyboard shortcuts

Faster with a keyboard

On a laptop or desktop, you never need to touch the mouse. Every key below works while the Calculator page is open.

See every function
0–9.Numbers and decimal point
+-*/Add, subtract, multiply, divide
^()Powers and brackets
EnterCalculate the answer
BackspaceDelete the last item
EscClear everything
sctsin, cos, tan
lgrpln, log, square root, π
Three quick habits

Get correct answers first time

1

Check the angle mode

sin(30) is 0.5 in DEG but −0.988 in RAD. Glance at the badge in the top-left of the display.

2

Bracket negatives

−3^2 is −9 because powers come first. Write (−3)^2 when you mean 9.

3

Read the preview

If the faint answer looks wrong while you type, fix it before you build on it.

New to scientific functions?

Learn what every button does, then try real worked examples with one tap.

Functions guideWorked examples
Functions guide

Every button, explained

A plain-language reference for each key on the Calcora keypad, with an example you can check yourself.

TrigonometryPowers & rootsLogs & constantsOrder of operations

Trigonometry

Angles are read in the current mode. Inverse functions return an angle in that same mode.

sin

Sine

Opposite side divided by hypotenuse in a right triangle.

sin(30) = 0.5 · DEG
cos

Cosine

Adjacent side divided by hypotenuse.

cos(60) = 0.5 · DEG
tan

Tangent

Opposite divided by adjacent. Undefined at 90° and 270°.

tan(45) = 1 · DEG
sin⁻¹

Inverse sine

Finds the angle whose sine is the given value, between −1 and 1.

sin⁻¹(0.5) = 30 · DEG
cos⁻¹

Inverse cosine

Finds the angle whose cosine is the given value.

cos⁻¹(0) = 90 · DEG
tan⁻¹

Inverse tangent

Finds the angle whose tangent is the given value. Accepts any number.

tan⁻¹(1) = 0.785398… · RAD

Powers & roots

Power keys attach to whatever comes just before them, so press the number first.

x² x³

Square and cube

Multiplies a number by itself two or three times.

12^2 = 144
xʸ

Any power

Raises to any exponent, including fractions and negatives. Chains work right to left.

2^10 = 1024
√ ∛

Square and cube root

The number that, squared or cubed, gives your value. Cube roots accept negatives.

∛(−27) = −3
1/x

Reciprocal

One divided by the number, entered as a power of −1.

8^(−1) = 0.125
eˣ 10ˣ

Exponentials

Raise e or 10 to a power. The opposites of ln and log.

10^(3) = 1000
EXP

Scientific notation

Means “times ten to the power of”. Shows as E on the display.

6.022E23 = 6.022 × 10²³

Logarithms, constants & more

The keys that turn a basic calculator into a scientific one.

ln

Natural log

Logarithm to base e. Only defined for positive numbers.

ln(e) = 1
log

Common log

Logarithm to base 10. Handy for pH, decibels and orders of magnitude.

log(1000) = 3
π e

Constants

π ≈ 3.14159265359 and e ≈ 2.71828182846, stored to full precision.

2π = 6.28318530718
n!

Factorial

Multiplies every whole number from 1 up to n. Works up to 170!.

5! = 120
%

Percent

Divides the number before it by 100, so “of” becomes multiply.

200×15% = 30
Ans |x|

Previous answer & absolute value

Ans recalls your last result. |x| removes the minus sign.

abs(−7.5) = 7.5
Order of operations

How Calcora reads your expression

Calcora follows the standard mathematical order, the same one taught in school and used by handheld scientific calculators.

Tip: when in doubt, add brackets. They never hurt, and unclosed brackets are closed for you at the end.

  1. Brackets and functionsEverything inside ( ), including sin( and √(, is worked out first.
  2. Factorial and percentn! and % apply to the number right before them.
  3. Powersx^y, worked right to left: 2^3^2 = 2^9 = 512.
  4. Negative signsA leading minus applies after powers: −3^2 = −9.
  5. Multiply and divideLeft to right, including implied multiplication like 2π.
  6. Add and subtractLeft to right, last of all.

Degrees vs radians

Both measure angles. Pick the one your question uses.

DEG — degrees

A full turn is 360°. Used in everyday geometry, navigation and most school problems.

  • Right angle: 90
  • Straight line: 180
  • To radians: × π ÷ 180

RAD — radians

A full turn is 2π. Used in calculus, physics and engineering formulas.

  • Right angle: π/2 ≈ 1.5708
  • Straight line: π ≈ 3.1416
  • To degrees: × 180 ÷ π
Try some examples
Worked examples

Real problems, ready to try

Each example shows exactly what to type. Press “Try it” and the expression is loaded into the calculator for you — just hit equals.

Everyday maths

Quick calculations that come up at home, at work and at dinner.

Percent

An 18% tip on a $64.50 bill

The % key turns 18 into 0.18, so “of” simply becomes multiply.

64.5×18%
= 11.61Try it
Geometry

Area of a circle with a 7 cm radius

Area = πr². The power applies only to 7, not to π.

π×7^2
≈ 153.94 cm²Try it
Pythagoras

Diagonal of a 3 m by 4 m room

The hypotenuse is the square root of the sum of the squares.

√(3^2+4^2)
= 5 mTry it
Probability

Ways to pick 6 numbers from 49

Combinations: 49! ÷ (6! × 43!). Factorials make this one line.

49!÷(6!×43!)
= 13,983,816Try it

Science & engineering

Make sure the calculator is in DEG mode for the projectile example.

Physics

Peak height of a ball thrown at 20 m/s, 35° up

h = (v·sin θ)² ÷ 2g, with g = 9.81 m/s².

(20×sin(35))^2÷(2×9.81)
≈ 6.71 mTry it
Physics

Time to fall 45 metres

t = √(2h ÷ g), ignoring air resistance.

√(2×45÷9.81)
≈ 3.03 sTry it
Chemistry

pH of a solution with [H⁺] = 3.2 × 10⁻⁴

pH = −log[H⁺]. Use EXP for the power of ten.

−log(3.2E−4)
≈ 3.49Try it

Money & growth

Powers and logarithms do the heavy lifting in finance.

Savings

$5,000 at 4.5% a year for 10 years

Compound growth: P × (1 + r)ⁿ.

5000×(1+0.045)^10
≈ $7,764.85Try it
Investing

Years to double money at 7%

Doubling time = ln 2 ÷ ln(1 + r).

ln(2)÷ln(1.07)
≈ 10.24 yearsTry it
Loans

Monthly payment on $20,000 at 6% over 5 years

Monthly rate 0.005, 60 payments: P·r ÷ (1 − (1 + r)⁻ⁿ).

20000×0.005÷(1−(1+0.005)^(−60))
≈ $386.66Try it

Common slip-ups

The four mistakes we see most — and how to avoid them.

Wrong angle mode

sin(90) gives 1 in DEG but 0.894 in RAD. If a trig answer looks odd, check the badge.

Squaring negatives

−4^2 = −16. To square negative four, type (−4)^2 = 16.

Fractions under one line

1÷2×3 is 1.5, not 1/6. Use 1÷(2×3) when the whole bottom is a product.

Percent changes

Adding 20% to 50 is 50×(1+20%) = 60, not 50+20% which adds 0.2.

About Calcora

A calculator that respects your time

Calcora started with a simple frustration: online calculators full of ads, tiny buttons and answers you couldn't trust. So we built the one we wanted to use.

Our story

From a borrowed handheld to your browser

Most of us learned maths on a plastic scientific calculator with a one-line screen. You typed a long formula, pressed equals, and hoped. One misplaced bracket and you started again.

Calcora keeps the familiar keypad but adds a full display, a live preview and a history you can reuse. It loads instantly, works on any phone or computer, and never asks you to sign up.

40+functions and keys
12significant digits shown
0accounts or ads
100%runs on your device
What we believe

Three principles behind every key

Private by design

Every calculation happens in your browser. Nothing you type is sent anywhere or stored after you close the tab.

Honest precision

Answers are rounded to 12 significant digits, so tiny computer rounding errors never show up as 0.30000000000000004.

Easy for everyone

Large keys, clear contrast, full keyboard support and readable error messages instead of a cryptic “Math ERROR”.

FAQ

Questions people ask

Is Calcora really free?

Yes. There are no paid tiers, no ads and no sign-up. Open the page and start calculating.

Can I use it in an exam?

That depends on your exam rules. Many exams only allow approved handheld calculators, so check with your teacher or exam board first.

How accurate are the answers?

Calcora calculates with standard double-precision numbers and shows up to 12 significant digits. Very large or small results switch to scientific notation automatically.

Does it work without internet?

Once the page has loaded, all calculations run on your device, so you can keep working even if your connection drops.

Why does tan(90) show an error?

Tangent of 90° is undefined — the value grows without limit. Calcora tells you so instead of printing a huge meaningless number.

Contact

Tell us what would make Calcora better

Found a bug, need a function we don't have yet, or want to use Calcora in your classroom? We read every message.

Send a message

Helpful feedback

What makes a great report

What you typed

Copy the exact expression from the display, brackets and all. Small details often matter.

What you expected

Tell us the answer you were expecting and where it came from — a textbook, another calculator or by hand.

Your device

Phone or computer, and which browser. It helps us check the layout and keyboard behaviour.

On our list for next time

Ideas already suggested by people like you. Vote by mentioning them in your message.

Hyperbolic functions

sinh, cosh and tanh for engineering students.

Memory keys

M+, M− and MR for running totals.

Fraction mode

Show answers like 3/8 as well as 0.375.

Unit conversions

Lengths, temperatures and angles in one place.

Back to the calculator