Tools

Choose a formula, enter what you know, leave the unknown blank — solved instantly with the rearranged equation.

Solve linear, quadratic, and simultaneous equations with step-by-step solutions and interactive graphs

Plot mathematical functions on an interactive canvas with zoom, pan, and multi-function overlay

Eight calculation modes in one tool: percent of, percent change, discount, tax, find the whole, and more — with instant work shown and visual charts.

Convert between standard, scientific, engineering and E-notation, round to significant figures, and count sig figs digit by digit.

Convert numbers to Roman numerals and Roman numerals back to numbers, instantly and accurately (1-3999).

Add, subtract, multiply, transpose, invert and find the determinant, rank and trace of matrices online

Differentiate any function step by step, evaluate f'(a), and see f and f' graphed together

Compute definite integrals numerically and see the signed area under the curve

Evaluate lim x→a f(x) numerically and visualize the approach from both sides with a table and graph

Turn a data table into a clean bar, line, pie or doughnut chart, then download it as a PNG image.

Pick a 3D solid, type its dimensions, and instantly get the volume and surface area — with a clear labeled diagram and extras like slant height and diagonal.

Drag the point around the circle and watch the angle, the six trig functions, and the sine and cosine waves update live — with exact values at every special angle.

Type a number and read it spelled out in words — correctly — in any of 12 languages. Handles decimals, negatives, the Indian lakh/crore system, the East-Asian 万/億 myriad system, and check-style currency amounts.

Count the significant figures in any number, see exactly which digits count and why, round to a chosen precision, and get the unambiguous scientific-notation form.

Every standard trig identity in one organized reference — and an interactive unit circle that shows sin θ, cos θ and tan θ live as you drag the angle, so the formulas actually make sense.

Every derivative and integral you need in one organized table — power, exponential, logarithmic, trigonometric, inverse-trig and hyperbolic rules — with one-tap links to our interactive derivative and integral solvers so you can work your own problem right away.

Every algebra formula you need in one organized table — the quadratic formula, exponent and logarithm rules, factoring and special products, radicals, lines and distance, and complex numbers — with one-tap links to our interactive equation solver and calculators so you can work your own problem right away.

Every geometry formula you need in one organized table — square, rectangle, triangle and polygon area, circle and ellipse formulas, volume and surface area for cubes, spheres, cylinders, cones and pyramids, the Pythagorean theorem and special right triangles, and coordinate geometry — with one-tap links to our interactive 3D solid visualizer and unit circle so you can explore the shape right away.

How big is that number, really? Understand it intuitively as 'how many' of everyday objects.

Type a formula to get its molar mass, element-by-element breakdown, and mole–gram–particle conversions.

Enter speed, angle and gravity, then watch the parabola fly. Range, peak height and flight time are computed instantly.

Play any frequency from 20 Hz to 20 kHz, then take the high-frequency hearing test to estimate your hearing age - all in your browser

Type any chemical reaction and get the balanced equation with the smallest whole-number coefficients — plus a table that proves every element is balanced.

Calculate radioactive decay for any half-life: solve for the amount remaining, the time elapsed or the half-life itself, convert between half-life, decay constant and mean lifetime, date samples by carbon-14, and watch the decay curve.

Calculate the heat energy needed to change a substance's temperature with Q = m·c·ΔT. Solve for any variable, pick from 19 material presets, switch mass and energy units, and enter ΔT directly or from an initial and final temperature.

Calculate percent error, percent yield and percent difference in one place. Enter your measured and accepted values to gauge accuracy, your actual and theoretical yield to find reaction efficiency, or any two measurements to compare them — with the formula, the signed error and a plain-English interpretation.

Type a chemical equation, give the amount of one or more reactants, and instantly see the balanced equation, the limiting reactant, the theoretical yield of each product (in moles and grams), the leftover excess reactant, and — if you enter an actual yield — the percent yield. Every amount can be grams, moles, or a solution given as molarity × volume.

Convert a value and see the work: the factor-label chain of conversion fractions with units cancelling diagonally, ending in your answer. Learn the method, not just the number.

Every common polyatomic ion in one organized chart — name, formula and charge, grouped from 1+ cations through 3− anions — with one-tap links to our interactive molar mass, equation balancer and stoichiometry calculators so you can put the ion to work right away.

Every fundamental physical constant in one searchable reference — CODATA 2022 recommended values, grouped by category, with the 7 exact constants that define the SI base units clearly marked. Search by name or symbol, filter by category, and copy any value with one tap.

Practice dosage calculation the way nursing school teaches it — by dimensional analysis. Enter an ordered dose, a weight-based mg/kg order, or an IV volume and time, and watch the factor-label chain cancel units diagonally to reach the amount to give, the total dose, or the flow and drip rate. Built for learning the method, with the working shown every time.

Find out how hot it actually feels by combining air temperature with humidity, using the same formula the National Weather Service uses for heat advisories.

Find out how cold it actually feels on exposed skin by combining air temperature with wind speed, using the official US/Canada wind chill formula.

Find the dew point — the temperature air must cool to for dew to form — and see how muggy or comfortable that actually feels, from air temperature and relative humidity.

Turn any value into every metric prefix at once. Slide from quetta (10^30) to quecto (10^-30), read a full magnitude table, and see exactly where your number lands on a visual ladder of the universe's scales.

Decode color bands into ohms or turn a resistance back into color bands, with a realistic resistor drawing

Decode a capacitor code like 104 into a capacitance, or turn a value back into its 3-digit code, with a realistic capacitor drawing

Compute V, I, R and P from any two values, size a voltage divider, or find the right series resistor for an LED

Convert power levels (dBm/dBW ⇄ W), compute dB ratios for power and voltage, and cascade gain in decibels

Estimate battery runtime from capacity and load, with real-world derating and Peukert's law for lead-acid

Add as many resistors or capacitors as you like, choose series or parallel, and get the combined value instantly

Calculate wire voltage drop, end voltage and power loss from current, length, gauge and material

Find the current-limiting resistor for one or more series LEDs from supply voltage, forward voltage and current

Convert American Wire Gauge to diameter, cross-section area, kcmil and resistance — and reverse-look up the nearest AWG

Calculate the frequency, period and duty cycle of a 555 astable oscillator, or the pulse width of a 555 monostable one-shot — with a timing waveform you can actually see.

Calculate capacitive and inductive reactance, RC and RL filter cutoff frequencies, and the resonant frequency of an LC circuit — with a log–log plot where the XC and XL curves cross at resonance.

Convert between binary, octal, decimal, and hexadecimal with real-time bit pattern visualization

Convert between text and ASCII/Unicode codes with encoding tools

Test regular expressions with real-time match highlighting and capture group display

Encode and decode Base64 with full UTF-8 support

Percent-encode and decode text for safe use in URLs

AND, OR, XOR, NOT and bit shifts on 32-bit integers, with a live bit-by-bit visualization

Beautify, minify and validate JSON instantly in your browser

Compute MD5 and SHA hashes from text right in your browser

Cryptographically strong random integers and decimals, with unique-draw mode and handy presets

Generate cryptographically random UUID v4 / GUID values in bulk and copy them with one click

Create QR codes for links, Wi-Fi, contacts, email, phone and SMS, then download as PNG or SVG

Paste a JSON Web Token and instantly decode its header and payload — entirely in your browser, nothing is uploaded

Convert CSV to JSON and JSON to CSV in your browser

Create strong, truly random passwords in your browser with adjustable length, character sets and a live strength meter

Calculate the network and broadcast address, host range, subnet mask and CIDR for any IPv4 address and prefix - right in your browser

Enter a value once and see it in every CSS length unit — px, rem, em, pt, %, vw and vh — with the root font-size, parent font-size and viewport you choose. Copy any result with one tap.

Paste or type your text and instantly see words, characters, sentences, reading time and more

Type or paste text and instantly get every common letter case, ready to copy

Generate placeholder text by paragraphs, sentences or words and copy it with one click

Translate text to Morse code and Morse code back to text, instantly and in your browser

Compare two blocks of text and instantly see added, removed and unchanged lines side by side

Convert between RGB, HEX, HSL, HSV, and CMYK with visual color picker and contrast checker

Calculate width, height, or aspect ratio for video, images and screens — keep 16:9, 4:3, 21:9 and more perfectly proportional.

Check text and background color contrast against WCAG 2.1 AA and AAA — instantly see the contrast ratio with a live preview and pass/fail badges.

Design beautiful linear, radial and conic CSS gradients with a live preview and copy the code in one click

Pick a paper size — A4, Letter, A3, Legal and every ISO and US standard — or enter a custom size, then see it in pixels, mm, cm, inches and points at any DPI. Copy any value with one tap.

Work out the pixel density of any display from its resolution and screen size, or the DPI you need to print an image sharply — with dot pitch, physical dimensions and a live density scale.

Pick a base color and instantly generate color-theory harmonies — complementary, analogous, triadic, tetradic, split-complementary and monochromatic — as live swatches you can copy as HEX, RGB, HSL, CSS variables or a Tailwind config.

Convert between Unix epoch time and human-readable dates

Stopwatch, countdown timer, and a live countdown to any date — all in one place

Add up daily and weekly work hours from clock-in and clock-out times, with automatic overtime and an optional pay estimate

Sunrise, sunset, twilight, golden hour and the moon phase for any place and date

Find the working-hours overlap across cities at a glance and pick a time that works for everyone

Create custom printable paper templates with live preview and instant PDF download

Convert between 30 world currencies with up-to-date exchange rates

Paste your ingredient list, set the servings, and get perfectly scaled amounts in fractions or decimals

Convert US, UK, EU and Japanese (cm) shoe sizes for men and women in one tap

Convert S/M/L and US, UK, EU and Japanese clothing sizes for women and men in one tap

Convert cups, tablespoons and spoons to grams and ounces — ingredient by ingredient, because flour and sugar don't weigh the same

Calculate the weight of steel, aluminum, copper and other metals — for bars, plates, pipes, tubes and angles, from real material densities

Add, subtract, multiply and divide feet, inches and fractions — then convert to decimal inches, feet, mm, cm and metres

Stop doing supermarket maths in your head. Enter the price and size of each product — in whatever unit it's sold in — and instantly see which one is the best value per kilogram, litre, metre or item. Compares up to four products and works across metric and imperial units, so 500 g vs 1.2 lb is no longer a guessing game.