calcu.lol
Visual calculators that help you understand math
311 matching calculators
Everyday & Practical
Unit Converter
Visual unit conversion
Tip & Bill Splitter
Split bills and tips instantly
Discount Calculator
See how much you save
Speed / Distance / Time
D = R × T solved visually
Age Calculator
Exact age from any date
Date Difference
Days between any two dates
BMI Calculator
BMI with health-zone gauge
Fuel Cost Calculator
Trip fuel cost visualized
Pace Calculator
Pace / distance / time solver
Sleep Calculator
Wake up between sleep cycles
Salary Calculator
Pay rate converter
TDEE / Calorie Calculator
BMR and TDEE from body stats
Electricity Cost Calculator
Power bill estimator
GPA Calculator
Weighted GPA from grades
Final Grade
Find the final-exam score needed to hit a target course grade
Business Days
Count business days (Mon-Fri) between two dates
Time Duration
Add or subtract two HH:MM:SS durations
Countdown
Count down to (or from) a target date and show days, hours, minutes
Work Hours & Time Card
Track daily hours worked and compute weekly pay
Unit Price & Best Deal
Compare price per unit across packages to find the cheapest deal
Budget Percentage Planner
Split a budget by percentages across categories with overage warnings
Map Scale Calculator
Convert between map distance and real-world distance using a representative fraction
Roof Pitch Calculator
Convert between rise/run, slope angle, and standard pitch labels
Stair Calculator
Plan stair rise, run, and tread depth with code-friendly guidance
Paint Coverage Calculator
Estimate gallons of paint needed for a room with deductions and coats
Tile Calculator
Estimate tile count and boxes for a floor or wall with waste margin
DMS Coordinate Converter
Convert latitude/longitude between decimal degrees and degrees-minutes-seconds
Bearing & Distance Calculator
Great-circle distance and bearing between two latitude/longitude points
Concrete Volume & Bags
Volume of slabs and columns plus bag count by yield
Tire Size Comparator
Parse and compare tire size codes like 225/45R17 by diameter and revs
Gear Ratio & RPM
Engine RPM, gear ratio, final drive, and tire diameter into vehicle speed
Time Zone Converter
Convert a time across IANA time zones using built-in Intl.DateTimeFormat
Recipe Scaler
Scale a recipe up or down by servings, with automatic ingredient unit conversion.
TDEE & Macros
Daily calorie needs and a macronutrient split
Finance & Money
Compound Interest
Watch your money grow
Loan Calculator
Monthly payments visualized
Savings Goal
Time to reach your goal
ROI Calculator
Investment return visualized
Break-Even Calculator
Cost vs. revenue crossover
Markup & Margin Calculator
Markup vs. margin side-by-side
Currency Converter
Convert currencies with an honest, dated rate snapshot.
Percent Change & CAGR
Calculate percent change between two values and CAGR over a number of periods
Sales Tax & VAT
Apply pre-tax discounts and sales tax / VAT to get the final price
Mortgage Affordability
Estimate the home price you can afford from income, debt, and target DTI
Debt Payoff Planner
Compare snowball vs avalanche debt payoff strategies across multiple debts
Rent vs Buy Calculator
Compare renting and buying total costs over a horizon with mortgage, taxes, and investment growth
Retirement Planner
Project retirement balance from contributions and returns, plus the 4% rule annual draw
NPV & IRR Calculator
Net present value and internal rate of return for a stream of cash flows
Black-Scholes Option Pricer
European option price, Greeks, and payoff diagram
Amortization Schedule
Loan payment table with a balance curve
Math & Algebra
Basic Calculator
Arithmetic operations visualized
Rule of Three
Proportion solving made visual
Percentage Calculator
Percentage calculations visualized
Trigonometry
Interactive unit circle
Fractions
Fraction arithmetic visualized
GCD / LCM
Factor visualization
Exponents & Roots
Powers and roots visualized
Logarithms
Interactive log curve
Statistics
Data visualization and stats
Quadratic Formula
Roots on a live parabola
Linear Equation / Slope
Line equation with graph
Number Base Converter
Binary, hex, octal converter
Combinations & Permutations
nCr and nPr visualized
Prime Factorization
Factor tree visualized
Sequences Calculator
Arithmetic & geometric sequences
Roman Numeral Converter
Decimal ↔ Roman numerals
Significant Figures
Sig figs identified & rounded
Matrix Calculator
Matrix operations step-by-step
Weighted Average
Compute a weighted mean from a list of values and corresponding weights
Z-Score
Compute the standard score z = (x - mean) / standard deviation
Binomial Probability
Binomial probability and cumulative distribution: exactly, at most, at least k successes
Polynomial Root Finder
Find real roots of a cubic ax³+bx²+cx+d via Cardano's formula plus the discriminant
Function Grapher
Plot one or more y=f(x) with intercepts and key points
Derivative Calculator
Numeric derivative f'(x) with a tangent line
Integral Calculator
Definite integral shown as shaded area under the curve
Limit Calculator
One- and two-sided limits, numerically and visually
Riemann Sum
Approximate area with left, right, midpoint, or trapezoid rectangles
Taylor Series
Taylor and Maclaurin polynomial approximation of a function
Extrema & Inflection Finder
Find maxima, minima, and inflection points of a function
Partial Derivatives
Partial derivatives and gradient of f(x,y)
Gradient & Directional Derivative
Gradient vector and directional derivative of a surface
Cubic Equation Solver
Real and complex roots of a cubic ax³+bx²+cx+d
Quartic Equation Solver
Roots of a degree-four polynomial
Polynomial Grapher
Graph a polynomial with its real roots and turning points
Polynomial Long Division
Divide polynomials with quotient and remainder
Completing the Square
Rewrite a quadratic in vertex form, step by step
Inequality Solver
Solve linear and quadratic inequalities on a number line
Absolute Value Solver
Solve absolute-value equations and inequalities
System of Equations (2×2)
Solve two linear equations with the intersection point
System of Equations (3×3)
Gaussian elimination for three unknowns
Slope-Intercept Explorer
Explore y=mx+b as slope and intercept change
Parametric Plotter
Plot parametric curves x(t), y(t)
Polar Grapher
Plot polar curves r(θ)
Rational Function Analyzer
Asymptotes, holes, and behavior of p(x)/q(x)
Piecewise Function
Evaluate and graph piecewise-defined functions
Matrix Determinant
Determinant with step-by-step reduction
Matrix Inverse
Invert a matrix via Gauss-Jordan elimination
Matrix Rank & Nullity
Rank, nullity, and reduced row echelon form
Eigenvalues & Eigenvectors
Eigenvalues and eigenvectors for 2×2 and 3×3 matrices
Singular Value Decomposition
Factor a matrix as U Σ Vᵀ
QR Decomposition
Factor a matrix as Q R via Gram-Schmidt
LU Decomposition
Factor a matrix as L U with partial pivoting
Gram-Schmidt Orthonormalization
Orthonormalize a set of vectors
Linear Transformation
Visualize how a 2×2 matrix transforms the plane
Row Reduction (RREF)
Reduce a matrix to row echelon form, step by step
Complex Number Calculator
Arithmetic, modulus, and argument on an Argand diagram
Complex Powers (De Moivre)
Powers and roots of complex numbers
Roots of Unity
The n nth-roots of unity on the unit circle
Quaternion Calculator
Quaternion arithmetic for 3D rotation
Mandelbrot Explorer
Zoom into the Mandelbrot set
Julia Set Explorer
Render Julia sets for any complex parameter
Unit Circle Explorer
Angles and trig values around the unit circle
3D Vector Calculator
Dot, cross, magnitude, and angle for 3D vectors
Extended Euclidean Algorithm
GCD with Bézout coefficients
Modular Arithmetic
Mod, modular inverse, and properties
Modular Exponentiation
Fast aᵇ mod m by repeated squaring
Chinese Remainder Theorem
Solve simultaneous congruences
Euler's Totient φ(n)
Count integers coprime to n
Diophantine Solver
Integer solutions of ax+by=c
Collatz Conjecture
3n+1 trajectory length and step plot
Sieve of Eratosthenes
Visualize the primes up to n
Divisors, τ(n) & σ(n)
Divisor list, count, and sum of divisors
Continued Fraction
Expand a number and its best rational approximations
Pascal's Triangle
Binomial coefficients in Pascal's triangle
Magic Square
Generate and validate magic squares
Graph Coloring
Color a graph with as few colors as possible
Sudoku Solver
Solve any Sudoku puzzle
Fourier Series
Approximate a periodic function with harmonics
FFT Calculator
Discrete Fourier transform and frequency spectrum
Normal Distribution
Bell curve PDF and CDF with shaded probabilities
t-Distribution
Student's t PDF, CDF, and critical values
Chi-Square Distribution
Chi-square PDF, CDF, and critical values
F-Distribution
F PDF, CDF, and critical values
Poisson Distribution
PMF and CDF for rare-event counts
Binomial Distribution
PMF and CDF for n independent trials
Hypergeometric Distribution
Sampling without replacement
Confidence Interval
Confidence interval for a mean or proportion
Hypothesis Test
z- and t-tests with p-value and rejection region
Bayes' Theorem
Posterior probability with a tree diagram
Correlation & Regression
Least-squares line with r and R²
Monte Carlo Simulator
Estimate π and integrals by random sampling
Monty Hall Simulator
Stay vs switch, simulated and exact
Geometry & Shapes
Triangle Solver
Visual triangle solving
Circle Calculator
Circle measurements visualized
Area & Perimeter
Shape area & perimeter
Volume Calculator
3D shape volume & surface area
Pythagorean Theorem
Right triangle solver
Coordinate Distance & Midpoint
Distance & midpoint on a grid
Regular Polygon Calculator
Any regular polygon
Ellipse Calculator
Calculate ellipse area, circumference approximation, eccentricity, and foci
Trapezoid Calculator
Solve trapezoid area, height, bases, median, and perimeter
Circle Sector Calculator
Calculate sector area, arc length, chord length, and perimeter
Arc Length Calculator
Solve arc length, radius, or angle for a circular arc
Conic Section Analyzer
Classify and graph a conic from its equation
Hyperbola Properties
Foci, vertices, and asymptotes of a hyperbola
Parabola Focus & Directrix
Focus, directrix, and vertex of a parabola
3D Distance & Midpoint
Distance and midpoint between two 3D points
Plane from 3 Points
Plane equation and normal vector from three points
Line-Plane Intersection
Where a line meets a plane in 3D
Rotation Matrix
2D and 3D rotation matrices from angles
Point in Polygon
Ray-casting point-in-polygon test
Convex Hull
Convex hull of a set of points
Voronoi Diagram
Voronoi regions for a set of points
Sphere & Solid Geometry
Surface area and volume of spheres, cones, and cylinders
Platonic Solids
Faces, edges, vertices, area, and volume of regular solids
Delaunay Triangulation
Triangulate a set of points (dual of Voronoi)
2D Vector Calculator
Add, subtract, and project 2D vectors
Science & Physics
Ohm's Law
V = I × R visualized
Kinematics Calculator
Motion equations visualized
Density Calculator
Mass, volume, density
Newton's Second Law
F = m × a visualized
Half-Life Calculator
Radioactive decay curve
Ideal Gas Law
PV = nRT with piston visual
Resistor Color Code
Decode resistor color bands and reverse lookup standard color codes
Voltage Divider
Solve resistor divider voltage, input, and resistor values
RC Time Constant
Calculate RC time constants and charge or discharge curves
Projectile Motion Calculator
Calculate projectile flight time, range, height, and velocity components
Work Energy Power Calculator
Calculate work, kinetic energy, potential energy, and power
Waves Calculator
Solve wave speed, frequency, wavelength, and period
Molarity Calculator
Calculate molarity, moles, or volume from the concentration formula C = n/V
Dilution Calculator
Solve dilution problems with C₁V₁ = C₂V₂ for any unknown variable
Molar Mass Calculator
Calculate molar mass from a molecular formula like H2O, NaCl, or C6H12O6
Simple Harmonic Motion
Position, velocity, and acceleration of an oscillator
Damped Oscillation
Under-, critically-, and over-damped motion
Wave Superposition
Add waves to see interference and beats
Beat Frequency
Beats produced by two close frequencies
Pendulum
Period of a simple pendulum
Doppler Effect
Frequency shift for a moving source or observer
Snell's Law
Refraction angle and critical angle with a ray diagram
Thin Lens & Mirror
Image distance, magnification, and ray diagram
Gravitational Force
Newton's law of universal gravitation
Orbital & Escape Velocity
Orbital period, circular velocity, and escape velocity
pH / pOH Calculator
pH, pOH, [H⁺], and [OH⁻] with an acidity scale
Chemical Equation Balancer
Balance chemical reactions via linear algebra
Tech & Digital
Download Time Calculator
How long will it take?
File Size Converter
Bytes ↔ KB ↔ MB ↔ GB ↔ TB
Color Code Converter
HEX ↔ RGB ↔ HSL ↔ HSV
Aspect Ratio Calculator
Scale & reduce dimensions
Screen PPI Calculator
Pixels per inch from resolution
Password Entropy
Password strength in bits
Base64 Encode & Decode
Encode text to base64 and decode base64 back to text
URL Encoder
Percent-encode and decode URLs and query strings
Unix Timestamp
Convert between Unix epoch seconds and ISO 8601 datetimes
Hash & Checksum
Generate SHA-1, SHA-256, SHA-384, and SHA-512 digests of text
JSON Formatter
Format, validate, and minify JSON with helpful error messages
Color Contrast Checker
Check WCAG AA/AAA contrast ratio between two colors
CSS Clamp
Generate responsive CSS clamp() values for fluid typography
DPI & Print Size
Compute pixel size, print size, and image resize math
Regex Tester
Test JavaScript regular expressions against sample text with match groups
QR Code Generator
Generate styled QR codes from text or URLs with PNG and SVG download.
RSA Demonstrator
Educational RSA key generation, encryption, and decryption
Unit Converters
Celsius to Fahrenheit
°C to °F converter
Fahrenheit to Celsius
°F to °C converter
Celsius to Kelvin
°C to K converter
Fahrenheit to Kelvin
°F to K converter
cm to Inches
cm to in converter
Inches to cm
in to cm converter
km to Miles
km to mi converter
Miles to km
mi to km converter
Feet to Meters
ft to m converter
Meters to Feet
m to ft converter
mm to Inches
mm to in converter
Inches to Feet
in to ft converter
Yards to Meters
yd to m converter
Feet to cm
ft to cm converter
Meters to km
m to km converter
Nautical Miles to Miles
NM to mi converter
Meters to Yards
m to yd converter
cm to Feet
cm to ft converter
kg to lbs
kg to lbs converter
lbs to kg
lbs to kg converter
Ounces to Grams
oz to g converter
Grams to Ounces
g to oz converter
kg to Stone
kg to st converter
Tons to kg
t to kg converter
mg to Grams
mg to g converter
Pounds to Ounces
lbs to oz converter
Carats to Grams
ct to g converter
Troy Ounces to Grams
ozt to g converter
GB to MB
GB to MB converter
MB to GB
MB to GB converter
TB to GB
TB to GB converter
Mbps to MB/s
Mbps to MB/s converter
MB/s to Mbps
MB/s to Mbps converter
Gbps to Mbps
Gbps to Mbps converter
KB to MB
KB to MB converter
Kbps to Mbps
Kbps to Mbps converter
GiB to GB
GiB to GB converter
Bits to Bytes
bit to byte converter
MB to KB
MB to KB converter
GB to TB
GB to TB converter
Liters to Gallons
L to gal converter
Gallons to Liters
gal to L converter
mL to Fluid Ounces
mL to fl oz converter
Cups to mL
cup to mL converter
Pints to Liters
pt to L converter
Quarts to Liters
qt to L converter
Tablespoons to mL
tbsp to mL converter
Teaspoons to mL
tsp to mL converter
Liters to Cups
L to cup converter
Cubic Meters to Liters
m³ to L converter
km/h to mph
km/h to mph converter
mph to km/h
mph to km/h converter
km/h to m/s
km/h to m/s converter
m/s to km/h
m/s to km/h converter
Knots to km/h
kn to km/h converter
Knots to mph
kn to mph converter
Square Meters to Square Feet
m² to ft² converter
Square Feet to Square Meters
ft² to m² converter
Acres to Hectares
ac to ha converter
Hectares to Acres
ha to ac converter
Square Meters to Acres
m² to ac converter
Square km to Square Miles
km² to mi² converter
Cups to Grams
cup to g converter
Grams to Cups
g to cup converter
Fluid Ounces to mL
fl oz to mL converter
Tablespoons to Teaspoons
tbsp to tsp converter
mL to Cups
mL to cup converter
MPG to L/100km
MPG to L/100km converter
L/100km to MPG
L/100km to MPG converter
km/L to MPG
km/L to MPG converter
Watts to Kilowatts
W to kW converter
Horsepower to Watts
hp to W converter
kWh to Joules
kWh to J converter
Joules to Calories
J to cal converter
Calories to Joules
cal to J converter
BTU to Joules
BTU to J converter
Watts to Horsepower
W to hp converter
kcal to kJ
kcal to kJ converter
PSI to Bar
PSI to bar converter
Bar to PSI
bar to PSI converter
atm to PSI
atm to PSI converter
Pascals to atm
Pa to atm converter
mmHg to atm
mmHg to atm converter
Hours to Minutes
hr to min converter
Minutes to Hours
min to hr converter
Days to Hours
day to hr converter
Seconds to Minutes
sec to min converter
Weeks to Days
wk to day converter
px to rem
px to rem converter
px to em
px to em converter
px to pt
px to pt converter
Amps to Milliamps
A to mA converter
kWh to Wh
kWh to Wh converter
Volts to Millivolts
V to mV converter
Hz to kHz
Hz to kHz converter
MHz to GHz
MHz to GHz converter
Degrees to Radians
deg to rad converter
Radians to Degrees
rad to deg converter
Newtons to Pound-force
N to lbf converter
Newton-meters to Foot-pounds
N·m to ft·lb converter