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General & Everyday Calculators for daily life — percentages, tips, dates and quick math. 18 tools
Percentage Calculator Find a percent of a number, percentage change, and what % one number is of another. Tip Calculator Split a bill fairly and work out the tip per person in seconds. Discount Calculator Work out the sale price and how much you save from a percentage discount. Average Calculator Find the mean, sum and count of any list of numbers. Ratio Calculator Solve and scale ratios, and reduce them to simplest form. Age Calculator Find an exact age in years, months and days from a date of birth. Date Difference Count the days, weeks and months between any two dates. Basic Calculator A fast everyday calculator — add, subtract, multiply, divide, percentages and memory keys. Scientific Calculator Trigonometry, logarithms, powers, roots, factorials and constants — with degree/radian modes. Fraction Calculator Add, subtract, multiply and divide fractions, with the result simplified to lowest terms. GCF & LCM Greatest common factor and least common multiple of a set of whole numbers. Prime Number Checker Check whether a number is prime, show its prime factorisation and the next prime. Random Number Generator Generate random numbers in a range. Adjust any field (or hit Reset) to roll again. Rounding Calculator Round a number to a chosen number of decimal places, or up/down/towards zero. Grade Calculator Weighted average grade from your scores and their weights. Final Grade Calculator The score you need on the final exam to reach your target grade. Speed · Distance · Time Solve for speed, distance or travel time from the other two values. GPA Calculator Grade point average on the 4.0 scale from letter grades and credits.
Unit Converters Every measurement system — length, weight, temperature and beyond. 19 tools
Length Converter Convert between mm, cm, m, km, inches, feet, yards and miles. Weight Converter Convert between grams, kilograms, pounds, ounces and stone. Temperature Converter Convert between Celsius, Fahrenheit and Kelvin. Area Converter Convert between m², km², square feet, acres and hectares. Volume Converter Convert between millilitres, litres, cups, pints and gallons. Speed Converter Convert between km/h, mph, m/s and knots. Data Storage Converter Convert between bits, bytes, KB, MB, GB and TB. Pressure Converter Convert between pascals, bar, psi, atm, mmHg and Torr. Energy Converter Convert between joules, calories, watt-hours, kWh and BTU. Power Converter Convert between watts, kilowatts, horsepower and BTU/h. Angle Converter Convert between degrees, radians, gradians, arcminutes and turns. Cooking Converter Convert between teaspoons, tablespoons, cups, fluid ounces and millilitres. Currency Converter Convert between major world currencies using live mid-market exchange rates. Fuel Economy Converter Convert between MPG (US/UK), km/L and L/100km — including the inverse L/100km scale. Density Converter Convert density between kg/m³, g/cm³, lb/ft³ and more. Force Converter Convert force between newtons, kilogram-force, pounds-force and dynes. Torque Converter Convert torque between N·m, lbf·ft, lbf·in and kgf·m. Flow Rate Converter Convert flow between L/s, L/min, m³/h, GPM and CFM. Shoe Size Converter Convert shoe sizes between US, UK, EU and Japanese (cm) systems.
Finance & Business Loans, investing, tax and business math for everyday money decisions. 20 tools
Loan EMI Calculator Calculate your Equated Monthly Instalment, total interest and full amortisation schedule for any loan. Simple Interest Interest earned on principal only, with no compounding. Compound Interest See how an investment grows with compounding over time. Mortgage Calculator Estimate monthly home-loan repayments and total interest. GST / VAT Calculator Add or remove sales tax from any amount. ROI Calculator Return on investment as a percentage and net gain. CAGR Calculator Compound annual growth rate of an investment. Savings & FD Maturity value of a fixed deposit or recurring savings. Profit Margin Gross profit and margin from cost and selling price. Salary Calculator Convert a wage between hourly, weekly, monthly and annual pay. SIP Calculator Future value of a monthly systematic investment plan. Break-Even Calculator Units and revenue needed to cover your costs. Markup Calculator Selling price and margin from cost and markup percentage. Down Payment Calculator Down payment and loan amount for a home or big purchase. Inflation Calculator How inflation changes the cost and buying power of money over time. Credit Card Payoff How long to clear a card balance and the interest it will cost. Loan Affordability The loan amount a monthly budget can support at a given rate. Savings Goal The monthly saving needed to reach a target amount by a deadline. Debt-to-Income Ratio The ratio lenders use to decide how much you can borrow. Overtime Pay Calculator Total pay from regular hours, overtime hours and the overtime rate.
Health & Fitness BMI, calories, body composition and wellbeing tools. 17 tools
BMI Calculator Body Mass Index and weight category from height and weight. BMR Calculator Basal metabolic rate — calories burned at complete rest. TDEE Calculator Total daily energy expenditure from BMR and activity level. Calorie Calculator Daily calories to maintain, lose or gain weight. Ideal Weight Healthy weight range for your height. Body Fat % Estimate body-fat percentage from BMI, age and sex. Water Intake Daily hydration target based on body weight. Pregnancy Due Date Estimated delivery date from the last menstrual period. Macro Calculator Protein, carbs and fat grams from a daily calorie target. Ovulation Calculator Estimate your fertile window from your last period and cycle length. Pace Calculator Running pace and speed from distance and time. One-Rep Max Estimate your 1RM and training loads from a lift. Heart Rate Zones Training zones from your age and resting heart rate. Waist-to-Hip Ratio WHR and health-risk category from waist and hip measurements. Steps to Distance & Calories Turn a step count into distance walked and calories burned. Calories Burned Calculator Energy burned by an activity, based on MET values, weight and duration. Lean Body Mass Calculator Estimate lean mass and fat mass from height, weight and sex.
Mathematics Algebra, geometry and trigonometry with worked solutions. 12 tools
Quadratic Solver Roots of ax² + bx + c = 0, real or complex. Logarithm Calculator Logarithm of a number in any base, plus natural and base-10 logs. Triangle Solver Area, hypotenuse and angles of a right triangle from two sides. Trigonometry sin, cos, tan and their inverses for any angle. Area Calculator Area of a circle, rectangle, triangle or trapezoid from its dimensions. Volume Calculator Volume of a cube, box, sphere, cylinder or cone from its dimensions. Pythagorean Theorem Find the hypotenuse or a missing leg of a right triangle. Slope Calculator Slope, line equation, distance and midpoint from two points. Exponent Calculator Raise a number to any power, including negative and fractional exponents. Decimal to Fraction Convert any decimal to a simplified fraction or mixed number. Scientific Notation Converter Convert any number to and from scientific, E and engineering notation. Percent Error Calculator Compare a measured value against the true value as a percentage.
Statistics Descriptive stats, spread and probability. 10 tools
Mean, Median & Mode Central tendency of a data set in one place. Standard Deviation Variance and standard deviation, sample or population. Z-Score Calculator Standardise a value against a distribution. Probability Single and combined event probabilities. Permutations & Combinations nPr and nCr for counting problems. Confidence Interval Confidence interval and margin of error for a sample mean. Sample Size Calculator How many survey responses you need for a target margin of error. Percentile Calculator Find any percentile and the quartiles of a list of numbers. Correlation & Linear Regression Pearson correlation, best-fit line and R² from two paired data sets. Binomial Probability Chance of exactly, at most or at least k successes in n independent trials.
Computer Science Number bases, hashing, encoding and networking. 9 tools
Number Base Converter Convert between binary, octal, decimal and hexadecimal. Base64 Encode / Decode Encode text to Base64 or decode it back. Color Converter Convert colours between HEX, RGB and HSL. Subnet / CIDR Network range, mask and host count from CIDR notation. Download Time Calculator How long a file takes to download at a given connection speed. Aspect Ratio Calculator Simplify a width and height to a ratio, and resize without distortion. Bitwise Calculator AND, OR, XOR, NOT and bit shifts of two integers, with binary shown. PPI / Pixel Density Calculator Pixels per inch and dot pitch from a screen resolution and diagonal size. Video File Size Calculator File size from bitrate and duration — or the bitrate a size budget allows.
Miscellaneous Specialty and home tools — paint, tiles, recipes. 14 tools
Paint Coverage Litres of paint needed to cover a room. Tile Estimator Number of tiles and boxes needed for a floor. Recipe Scaler Scale ingredient quantities up or down by servings. Numerology Life path number from a date of birth (just for fun). Fuel Cost Calculator Estimate the fuel cost of a trip from distance, economy and price. Unit Price Calculator Work out price per unit to compare product sizes. Electricity Cost Running cost of any appliance from its wattage and daily use. Concrete Calculator Concrete volume and bags needed for a slab, with waste allowance. Ohm's Law Solve voltage, current or resistance — with power — from the other two. Wind Chill What cold air really feels like once wind speed is factored in. Heat Index What hot weather really feels like once humidity is factored in. Mulch, Gravel & Soil Calculator Volume, weight and bags of landscaping material for any bed or path. Roof Pitch Calculator Pitch, angle, slope factor and rafter length from rise and run. Resistor Colour Code Decode a 4-band resistor into resistance and tolerance.
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Plain-language guides to the maths behind everyday decisions.
Why computers count in binary — and where hexadecimal fits in Binary is not arbitrary and hexadecimal is not a separate system. Why both exist, why 255 turns up everywhere, and why your 1 TB drive shows as 931 GB. HEX, RGB and HSL: three ways of writing the same colour Every screen colour is a mix of red, green and blue light. HEX and RGB write it one way, HSL another — and one of them is far easier to work with. What inflation quietly does to money sitting in the bank Cash does not lose value visibly — the balance never drops. But at 4% inflation, money left idle for a decade buys about a third less than it did.
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