Free Online Calculators & Converters

Instant online calculators and unit converters. Calculate BMI, percentages, dates, convert currencies, temperatures, and more — free and browser-based.

Percentage Calculator

Calculate percentages easily. Find percentage of a number, percentage change, increase, decrease, and ratio conversions.

What is X% of Y calculationPercentage change between two numbers

Open

Age Calculator

Calculate your exact age in years, months, days, hours, and minutes. Find age between any two dates precisely.

Exact age in years, months, and daysAge in total days, hours, and minutes

Open

BMI Calculator

Calculate your Body Mass Index with height and weight. Get BMI category, healthy weight range, and health insights.

BMI calculation with metric and imperial unitsBMI category classification

Open

Unit Converter

Convert between units of length, weight, volume, area, and more. Comprehensive unit conversion tool with 100+ units.

Length, weight, volume, area, and speed conversionsOver 100 units across 10 categories

Open

Speed Converter

Convert between speed units like mph, km/h, knots, and m/s. Calculate speed conversions for any velocity measurement.

Convert between 8+ speed unitsMiles per hour, km/h, knots, m/s, and more

Open

Data Storage Converter

Convert between data storage units. Calculate bytes, KB, MB, GB, TB, and more with binary and decimal options.

Binary (1024) and decimal (1000) base optionsBits through exabytes and beyond

Open

Number System Converter

Convert between decimal, binary, octal, and hexadecimal number systems. Translate numbers across different bases instantly.

Decimal, binary, octal, and hexadecimal conversionCustom base conversion (base 2 through 36)

Open

Roman Numeral Converter

Convert between Roman numerals and Arabic numbers. Translate numbers to Roman numeral format and back instantly.

Arabic to Roman numeral conversionRoman to Arabic number conversion

Open

Temperature Converter

Convert between Celsius, Fahrenheit, and Kelvin temperatures. Instant temperature conversion with formula display.

Celsius, Fahrenheit, and Kelvin conversionRankine and Réaumur scales included

Open

Time Zone Converter

Convert times between world time zones. Schedule meetings across time zones with this easy-to-use converter tool.

Convert between 400+ time zonesVisual time comparison across zones

Open

Currency Converter

Convert between world currencies with live exchange rates. Calculate currency conversions for 150+ currencies instantly.

150+ world currencies supportedReal-time exchange rate data

Open

Loan/EMI Calculator

Calculate loan EMI, total interest, and amortization schedule. Plan mortgages, car loans, and personal loans easily.

Monthly EMI calculationTotal interest and total payment amounts

Open

Discount Calculator

Calculate sale prices and savings from percentage discounts. Find the final price after single or multiple discounts.

Calculate discounted price from percentage offChain multiple discounts together

Open

Tip Calculator

Calculate tips and split bills easily. Determine tip amounts, per-person shares, and total costs for any group size.

Calculate tip at any percentageSplit bill among any number of people

Open

GPA Calculator

Calculate your GPA from course grades and credit hours. Support for 4.0, weighted, and cumulative GPA calculations.

Standard 4.0 scale GPA calculationWeighted GPA with credit hours

Open

Color Code Converter

Convert color codes between HEX, RGB, HSL, and CMYK formats. Translate any color value to other color systems.

HEX, RGB, HSL, HSV, and CMYK conversionsLive color preview swatch

Open

Aspect Ratio Calculator

Calculate aspect ratios for images and videos. Find dimensions while maintaining proportions for any screen or media.

Calculate ratio from any width and heightResize dimensions maintaining ratio

Open

Electricity Cost Calculator

Calculate electricity costs for appliances and devices. Estimate power consumption and monthly energy bills easily.

Calculate cost from watts and usage hoursDaily, monthly, and yearly cost projections

Open

Fuel Cost Calculator

Calculate fuel costs for any trip. Estimate gas expenses based on distance, fuel efficiency, and current gas prices.

Trip cost based on distance and fuel priceMPG and L/100km fuel efficiency input

Open

Date Difference Calculator

Calculate the exact difference between two dates. Find days, weeks, months, and years between any two dates easily.

Difference in years, months, weeks, and daysTotal days, hours, and minutes between dates

Open

Salary to Hourly Calculator

Convert annual salary to hourly wage, or hourly rate to annual salary. See your pay broken down by hour, day, week, month, and year.

Salary to hourly rate conversionHourly to annual salary conversion

Open

Sales Tax Calculator

Calculate sales tax and total price from any pre-tax amount. Or remove tax from a total to find the original price. Includes all US state tax rates.

Add tax to a price instantlyRemove tax from a total (reverse calculation)

Open

Scientific Notation Calculator

Convert numbers to and from scientific notation. Multiply, divide, add, and subtract numbers in scientific notation with step-by-step solutions.

Convert standard numbers to scientific notationConvert scientific notation to standard form

Open

Square Root Calculator

Calculate the square root, cube root, or any nth root of a number instantly. Also computes squares, cubes, and shows nearby perfect squares.

Square root of any numberCube root calculation

Open

Grade Calculator

Calculate your test grade as a percentage and letter grade. Also compute weighted course grades and find out what score you need on a final exam.

Test grade: points to percentage and letter gradeCourse grade: weighted average of multiple assignments

Open

ROI Calculator

Calculate return on investment (ROI) as a percentage. Enter your initial investment and final value to see net profit, ROI, and annualized returns.

ROI percentage calculationNet profit and final value display

Open

BMR Calculator

Calculate your Basal Metabolic Rate (BMR) and daily calorie needs at different activity levels using the Mifflin-St Jeor equation.

BMR using Mifflin-St Jeor formulaTDEE at 5 activity levels

Open

Calorie Calculator

Calculate your daily calorie needs based on your stats, activity level, and weight goal. Get macro breakdowns and projected weight change.

Daily calorie target based on goalSix weight goals from lose 2 lbs to gain 1 lb/week

Open

Ideal Weight Calculator

Calculate your ideal body weight using four medical formulas: Hamwi, Devine, Robinson, and Miller. See results in kg and lbs plus healthy BMI range.

Four ideal weight formulas comparedHamwi, Devine, Robinson, and Miller formulas

Open

Body Fat Calculator

Estimate your body fat percentage using the US Navy method with body measurements. Shows fat mass, lean mass, and body fat category.

US Navy body fat formulaSeparate male and female formulas

Open

Calorie Deficit Calculator

Calculate the daily calorie deficit needed to reach your weight loss goal. Set a time target or weekly loss rate and see your projected weight timeline.

Calorie deficit by time goal or weekly lossDaily and weekly deficit calculation

Open

Water Intake Calculator

Calculate your recommended daily water intake based on your weight, activity level, and climate. Results shown in liters, fl oz, cups, and glasses.

Personalized daily water recommendationAdjustments for activity level and climate

Open

Sleep Calculator

Calculate the best time to go to bed or wake up based on 90-minute sleep cycles. Wake up refreshed by timing your sleep to complete full cycles.

Wake-up time to ideal bedtimesBedtime to ideal wake-up times

Open

Pythagorean Theorem Calculator

Calculate any side of a right triangle using the Pythagorean theorem (a² + b² = c²). Find the hypotenuse or any leg with step-by-step solutions.

Find hypotenuse from two legsFind any leg from hypotenuse and other leg

Open

Circumference Calculator

Calculate the circumference, area, diameter, arc length, and sector area of a circle from radius or diameter. Instant results with formulas shown.

Circumference from radius or diameterCircle area calculation

Open

Area Calculator

Calculate the area and perimeter of 7 shapes: rectangle, circle, triangle, trapezoid, parallelogram, ellipse, and regular polygon. Step-by-step formulas.

7 shape types supportedRectangle, circle, triangle, trapezoid

Open

Quadratic Formula Calculator

Solve any quadratic equation ax² + bx + c = 0 instantly. Finds real and complex roots, discriminant, vertex, and axis of symmetry with step-by-step solutions.

Solves ax² + bx + c = 0 for any coefficientsHandles real and complex roots

Open

Fraction Calculator

Add, subtract, multiply, and divide fractions with step-by-step solutions. Also simplifies fractions and converts results to decimals and mixed numbers.

Addition, subtraction, multiplication, divisionSimplify a single fraction

Open

GCF and LCM Calculator

Find the Greatest Common Factor (GCF) and Least Common Multiple (LCM) of 2–6 numbers using prime factorization with full step-by-step explanations.

GCF for up to 6 numbersLCM for up to 6 numbers

Open

Prime Factorization Calculator

Find the prime factors of any number up to 10 billion. Shows prime factorization in exponential form, all divisors, factor pairs, and whether the number is prime.

Prime factorization up to 10 billionExponential form output (e.g., 2³ × 3²)

Open

Average Calculator

Calculate mean, median, mode, range, standard deviation, and more from a list of numbers. Enter values comma-separated or one per line.

Mean (arithmetic average)Median and mode

Open

Mortgage Calculator

Calculate your monthly mortgage payment, total interest, and view a full amortization schedule. Enter home price, down payment, interest rate, and loan term.

Monthly payment (principal & interest)Down payment in dollars or percent

Open

Retirement Calculator

Calculate how much you will have at retirement based on current savings, monthly contributions, annual return rate, and time horizon. Includes inflation adjustment.

Future value with compound growthMonthly contribution modeling

Open

Auto Loan Calculator

Calculate your monthly car payment, total cost, and interest for any auto loan. Includes trade-in value, sales tax, and a month-by-month amortization breakdown.

Monthly car payment calculationTrade-in value deduction

Open

Compound Savings Calculator

Calculate how your savings grow with compound interest over time. Add regular monthly contributions and see interest earned year by year.

Compound interest with regular contributionsMonthly, quarterly, or annual compounding

Open

Net Worth Calculator

Calculate your net worth by entering all your assets and liabilities. Get a clear picture of your financial health with totals and debt-to-asset ratio.

Assets categories: cash, investments, real estate, vehiclesLiabilities: mortgage, loans, credit cards, debts

Open

Paycheck Calculator

Calculate your take-home pay after federal taxes, state taxes, Social Security, Medicare, 401(k), and health insurance deductions. 2024 US tax brackets.

2024 US federal income tax bracketsSocial Security (6.2%) and Medicare (1.45%) deductions

Open

Standard Deviation Calculator

Calculate standard deviation, variance, mean, and other statistics for any dataset. Supports both population (÷N) and sample (÷N−1) formulas.

Population and sample standard deviationVariance (σ² and s²)

Open

Z-Score Calculator

Calculate z-scores and find probabilities for normal distributions. Convert raw scores to z-scores or find the probability area under the curve.

Z-score from raw value, mean, and standard deviationProbability below, above, and within z

Open

Confidence Interval Calculator

Calculate confidence intervals for means and proportions. Choose from 80% to 99.9% confidence levels with automatic z-score lookup.

Confidence intervals for means and proportionsConfidence levels: 80%, 85%, 90%, 92%, 95%, 96%, 98%, 99%, 99.9%

Open

Probability Calculator

Calculate probabilities for single events, compound events, Bayes' theorem, and binomial distributions. Essential for statistics and data science.

Single event probabilityCompound events (AND, OR)

Open

Combination & Permutation Calculator

Calculate combinations C(n,r) and permutations P(n,r) instantly. Find how many ways to choose or arrange items from a set.

Combination C(n,r) — order does not matterPermutation P(n,r) — order matters

Open

Percentile Calculator

Calculate percentiles and quartiles for any dataset. Find the value at a given percentile, or find what percentile rank a specific value falls at.

Find value at any percentile (P10 through P99)Find percentile rank of any value

Open

Margin of Error Calculator

Calculate the margin of error for surveys and polls, or find the sample size needed to achieve a desired margin of error at any confidence level.

Margin of error from sample sizeRequired sample size for target margin of error

Open

Normal Distribution Calculator

Calculate probabilities under the normal distribution curve. Find P(X ≤ x), P(X ≥ x), or P(a ≤ X ≤ b) for any mean and standard deviation.

P(X ≤ x), P(X ≥ x), and P(a ≤ X ≤ b)Custom mean (μ) and standard deviation (σ)

Open

Right Triangle Calculator

Solve any right triangle given 2 known values: sides a, b, c (hypotenuse) or acute angles A and B. Calculates all sides, angles, area, and perimeter.

Solve with any 2 known valuesCalculates all 3 sides and 2 angles

Open

Law of Sines Calculator

Solve any triangle using the Law of Sines: a/sin(A) = b/sin(B) = c/sin(C). Works for ASA, AAS, and SSA triangle configurations.

Solves ASA, AAS triangle configurationsFinds all sides, angles, and area

Open

Law of Cosines Calculator

Solve any triangle using the Law of Cosines: c² = a² + b² − 2ab·cos(C). Handles SAS (find side) and SSS (find angles) configurations.

SAS: find missing side given 2 sides + included angleSSS: find all angles given 3 sides

Open

Slope Calculator

Calculate the slope, equation, distance, midpoint, and angle of a line through two points. Includes y-intercept, x-intercept, and perpendicular slope.

Slope (rise over run)Y-intercept and x-intercept

Open

Distance Calculator (Points)

Calculate the distance between two points in 2D or 3D space using the distance formula. Also finds midpoint, slope, and angle.

2D distance: d = √(Δx² + Δy²)3D distance: d = √(Δx² + Δy² + Δz²)

Open

Midpoint Calculator

Find the midpoint between two points in 2D or 3D space. Also find a missing endpoint given one endpoint and the midpoint.

2D midpoint: M = ((x₁+x₂)/2, (y₁+y₂)/2)3D midpoint with z-coordinates

Open

Percent Error Calculator

Calculate percent error between an experimental (measured) value and a theoretical (accepted) value. Used in science, chemistry, and physics labs.

Percent error with absolute value (standard)Signed percent error (shows direction)

Open

Significant Figures Calculator

Count significant figures in any number, round to a specified number of sig figs, and apply significant figure rules to addition, subtraction, multiplication, and division.

Count significant figures in any numberRound to specified significant figures

Open

Roofing Calculator

Calculate roofing materials needed for any roof. Enter length, width, and pitch to get squares, shingle bundles, ridge cap, and nail count.

Pitch-adjusted roof areaShingle bundles (3 per square)

Open

Flooring Calculator

Calculate how much flooring you need for one or multiple rooms. Get total square footage, waste-adjusted area, and number of boxes.

Multiple room supportAdjustable waste %

Open

Mulch Calculator

Calculate cubic yards, cubic feet, and bags of mulch or topsoil for rectangular and circular garden beds.

Rectangular and circular shapesCubic yards, cubic feet, and bag counts

Open

Gravel Calculator

Calculate cubic yards, cubic feet, and tons of gravel, crushed stone, sand, fill dirt, or topsoil for any project.

5 material types with accurate densitiesVolume in cubic yards/feet

Open

Fence Calculator

Calculate fence posts, boards, rails, and concrete needed for a wood privacy fence.

Posts, boards, and rail linear footageConcrete for post holes

Open

Deck Calculator

Calculate deck boards, screws, and joists needed for a wood or composite deck.

Board count with wasteScrew estimate

Open

Drywall Calculator

Calculate drywall sheets, joint compound, tape, and screws for any room or multiple rooms.

Multi-room supportWall and ceiling area

Open

Lumber Calculator

Calculate board feet and linear feet for any lumber order. Add multiple pieces with different dimensions.

Board feet formula: T×W×L/12Multiple piece types with quantity

Open

Pool Volume Calculator

Calculate swimming pool volume in gallons and liters. Supports rectangular, oval, and round pools with variable depth.

Rectangular, oval, and round shapesGallons and liters output

Open

Wallpaper Calculator

Calculate how many rolls of wallpaper you need. Accounts for pattern repeat, roll dimensions, doors, and windows.

Pattern repeat allowanceDoor and window deductions

Open

Stair Calculator

Calculate stair rise, run, number of steps, stringer length, and angle from total floor-to-floor rise. Checks building code compliance.

Step count from total riseActual riser height distribution

Open

Insulation Calculator

Calculate insulation thickness and quantity needed to reach any R-value. Supports fiberglass batts, blown insulation, spray foam, and rigid foam.

6 insulation types with R-value per inchR-value presets R-13 through R-60

Open

Brick Calculator

Calculate bricks and mortar bags needed for any wall. Choose from 5 standard brick sizes.

5 brick sizesMortar bag estimate

Open

HVAC BTU Calculator

Calculate BTU heating or cooling capacity needed for any room. Accounts for insulation, climate zone, occupants, and windows.

BTU/hr from room dimensionsInsulation quality factor

Open

Solar Panel Calculator

Calculate how many solar panels you need based on monthly electricity usage. Get system size, annual output, CO2 offset, and estimated cost.

Panel count from monthly kWhSystem size in kW

Open

Garden Area Calculator

Calculate total garden bed area, soil volume, and plant count for multiple beds in rectangle, circle, or triangle shapes.

Multiple beds in one calculationRectangle, circle, triangle shapes

Open

Vinyl Siding Calculator

Calculate how many squares of vinyl or wood siding you need. Enter wall areas, exposure, and waste percentage.

Multiple wall supportOpening deductions

Open

Patio Calculator

Calculate patio pavers, setting sand, and base gravel needed for any patio or walkway project.

Paver count with joint widthSand and base gravel tonnage

Open

Gutter Calculator

Calculate gutter linear footage, downspout count, hangers, and elbows needed for any house.

Gutter footage from house dimensionsDownspouts by spacing

Open

Window Opening Calculator

Calculate rough opening dimensions and header size for windows and doors. Add multiple openings of different sizes.

Rough opening width and heightStructural header size recommendation

Open

Explore Other Categories