Free Online Calculators

Enter your current savings, monthly contribution, bonus contributions, expected return, and monthly spending to find the exact month you'll reach FIRE — and how many years and months away it is. It also lists your projected dates for hitting each net-worth milestone.

Add or remove sales tax / VAT from any price. Enter an amount and rate to instantly see the net price, tax amount, and gross total, with your choice of rounding.

Just enter the loan amount, annual interest rate and term to instantly calculate your monthly payment, total repayment and total interest. Supports equal-payment and equal-principal methods, with a modern chart of the principal-vs-interest breakdown.

Enter your starting principal, annual rate, term, and monthly contribution to estimate the future value, total contributions, and total interest. Switch between monthly and yearly compounding and view a year-by-year breakdown.

Pick a lottery type (Loto 6, Loto 7, Mini Loto, or Jumbo) and the number of tickets to calculate your odds of hitting the jackpot, your chance of winning any prize, and the expected payout rate. Compare the odds against everyday events to feel just how unlikely a win really is.

Enter your loan amount, interest rate and term, plus the share repaid through bonus payments and how often they occur, to instantly compute your monthly payment, each bonus payment, the annual and total repayment, and total interest using the equal-payment method. A year-by-year amortization schedule is included.

Enter your height and weight to instantly calculate your BMI, ideal weight (BMI 22), and weight category based on WHO/JASSO standards.

Estimate your basal metabolic rate (BMR) — the energy your body needs at rest — from your sex, age, height, and weight using the Harris-Benedict equation.

Just enter your height to calculate ideal, beauty, Cinderella and model weight at once by BMI standard. Enter your current weight to also see the gap to each goal.

Enter the time you want to wake up, or the time you go to bed, to get bedtime or wake-up times based on 90-minute sleep cycles. Set how long it takes you to fall asleep and see the times that help you wake up refreshed.

Calculate your estimated due date from your last menstrual period using Naegele's rule. Adjusts for cycle length and shows gestational age, estimated ovulation date, and days remaining.

Calculate how many weeks and days pregnant you are today (or on any as-of date) from your last menstrual period. Also shows gestational month, trimester and due date.

Enter a date of birth to find your exact age in years, plus days until your next birthday and the total number of days you have been alive.

Just enter a reference year and instantly build a chart showing each age alongside the birth year (Gregorian and Japanese era) and Chinese zodiac sign. Lists ages 0 to 120 at a glance.

Pick a start date and an end date to instantly find the number of days between them. Toggle whether both endpoints are counted, and see week, month, and year approximations at the same time.

Instantly count how many days are left until your target date. Get the days, weeks, months, and weekday remaining to an exam, birthday, anniversary, or deadline. For past dates, see how many days have elapsed.

Just enter your wedding date to list the exact calendar date of every milestone, paper, silver, gold and more, plus the days left until your next anniversary.

Pick a date of death and a denomination (Catholic or Protestant) to instantly list every memorial date, from Memorial Masses to memorial services.

Just enter a value and pick a unit to instantly convert between meters, centimeters, inches, feet, shaku, nautical miles, light-years and more. A single table shows the value in every other unit at once.

Convert between Celsius, Fahrenheit, Kelvin, Rankine, and Réaumur all at once. Just enter a value and pick its unit to see the full conversion table.

Convert weight and mass between grams, kilograms, tonnes, pounds, ounces, and more. Enter a value, pick its unit, and see a full conversion table instantly.

Enter a value and pick a unit to convert at once between mL, L, m³, cubic inches, cubic feet, US/UK gallons, pints and quarts, plus the Japanese go, sho, to and koku.

Free speed unit converter for km/h, m/s, mph, knots, ft/s, and Mach. Enter a value, pick its unit, and see every conversion in one table.

Just enter a value and pick a unit to instantly convert between nanoseconds, milliseconds, seconds, minutes, hours, days, weeks, months, years, and centuries. See every unit at once in a single table.

Just enter the number of prize types to estimate the average pulls needed to complete a full gacha set. Add the cost per pull for an expected-cost estimate, or a target probability for the pulls required (assuming equal odds).

Just enter your dog's or cat's age to instantly see how old they are in human years. It accounts for how small, medium, and large dogs age differently, and shows the life stage plus a handy age-conversion chart.

Estimate your car's annual, monthly, and per-kilometer running costs from automobile tax, insurance, shaken inspection, parking, fuel, and maintenance.

Calculate the building coverage ratio (%) from site area and building footprint. Reverse-calculate the maximum buildable area from a zoning limit, with corner-lot relaxation explained.

Enter the site area and total floor area to instantly get the floor area ratio (%). You can also work backward from a permitted ratio to find how much floor area you can build, plus an explanation of road-width limits.

Calculate the ideal shooting distance to your subject from a flash unit's guide number, aperture and ISO.

Calculate the area of a circle from its radius or diameter. Also shows circumference and diameter.

Find the square root, cube root, and nth root of any number at once. Supports real roots of negative numbers with odd indices, with a graph.

Enter a positive integer to get its prime factorization, plus the divisor count, divisor sum, full list of divisors, and a primality check.

Find the greatest common divisor (GCD) and least common multiple (LCM) of several integers using the Euclidean algorithm, with a step table and coprime check.

Solve a x²+b x+c=0 with the quadratic formula. The discriminant detects real, double, and complex roots, and the vertex, axis, and parabola graph are shown.

Find the area of a triangle from its base and height. The formula is area = base times height divided by 2, shown with a clear diagram of the triangle.

Enter your usage (kWh), per-kWh energy rate, fixed monthly base charge, and any renewable-energy levy to instantly estimate a monthly electricity bill. It also shows the breakdown of energy charge, base charge, and levy, plus the effective all-in unit price per kWh. Handy for checking an estimate against your meter reading.

Estimate the electricity cost and CO2 emissions of running an AC in cooling mode from its power draw (W), hours, and days. You can also pick by room size.

Just enter the temperature and humidity to calculate the discomfort index (DI), a measure of how muggy it feels. Instantly see comfort levels such as comfortable, slightly hot, or hot and sweaty.

Estimate the apparent temperature from air temperature, wind speed, and humidity. Using Missenard's formula, see how much colder it feels as the wind picks up.

Estimate the electricity cost and CO2 emissions of running your AC in heating mode, broken down per hour, day, and month.

Enter your driving distance, fuel economy, fuel type, and fuel price to instantly estimate fuel consumption (L), fuel cost, and CO2 emissions. Supports gasoline and diesel, and also shows CO2 emitted per kilometer.

Calculate sunrise, solar noon, and sunset times, day length, and the sun's noon altitude from latitude, longitude, date, and time zone using the NOAA solar position algorithm.

Enter a date to find the moon age, the moon phase (new moon, first quarter, full moon, last quarter and more), the illuminated fraction, and the days until the next full and new moon, with a diagram of the lit moon.

Find resistance from voltage and current using Ohms law R = V / I. It also computes power and conductance, with a simple circuit diagram.

Find free fall distance and speed from the fall time. With initial speed zero and gravity g=9.80665 m/s squared, it gives distance, speed in m/s and km/h, and kinetic energy per mass.

Find the speed of uniform motion from distance and time using v = d / t. Choose meters or kilometers and seconds, minutes, or hours, and read the result in both m/s and km/h.

Calculate the speed of sound in air from temperature. Shows m/s, km/h, Mach 1 reference, and time to travel 1 km.

Three basic percentage calculations in one: what percent A is of B, a given percent of a number, and the whole from a part and its percentage. Enter two numbers to instantly get the percent or amount, with your choice of decimal places and rounding.

Enter a starting (old) value and an ending (new) value to instantly get the percent change, the year-over-year ratio, and the absolute difference. Great for sales, prices, population, and traffic growth.

Simulate your Texas Hold'em win, tie and loss rates from your hole cards, the community cards and the number of opponents using a Monte Carlo method.

Calculate the probability that two people in a group of n share a birthday. Explore the surprising birthday paradox with a probability curve.

From your age, your parent's age, and how often you meet, this tool estimates how many more times you'll see them and the odds, based on life-table survival rates.

Calculate the probability of rolling a given total with several dice. Shows the exact probability of a target sum, the at-least and at-most probabilities, expected value, variance, and a bar chart of the distribution.

For a normal distribution N(μ, σ²) with a given mean and standard deviation, compute the probability density (PDF), cumulative probability (CDF), upper-tail probability and standardized z value at any x.

For a binomial distribution with n trials and success probability p, compute the probability mass P(X=k), cumulative probability, upper tail, mean, and variance, with a bar chart of the distribution.

From the mean lambda and a count k, compute the Poisson probability mass P(X=k), cumulative P(X less than or equal to k), and upper tail P(X at least k), with a bar chart of the distribution.

Compute the Student's t-distribution probability density (PDF), lower cumulative probability (CDF), upper tail, and two-sided probability (p-value) from a t value and degrees of freedom, with PDF and CDF graphs.

For a chi-square distribution with k degrees of freedom, compute the probability density, cumulative distribution (lower tail), upper-tail probability (p-value), mean, and variance at a given x, with PDF and CDF graphs.

Find the z value from a probability p and tail type (lower, upper, or two sided). This standard normal quantile tool computes critical values such as 1.96 with high precision.

Type an expression such as sin(x) or x^2-2 and instantly plot its graph over a chosen x range. Maximum, minimum, zeros, and sample point values are shown alongside.

Solve f(x) = 0 with Newton's method. Just enter the equation, initial guess, tolerance, and max iterations - the derivative is approximated automatically by numerical differentiation. Shows the approximate root, f(root), iteration count, error, plus a step table and a graph.

Solve f(x)=0 with the bisection method. Enter a function and an interval to get the approximate root, f(root), the iteration count, and the error, plus a per-step table of intervals and midpoints and a function graph.

Approximate a definite integral ∫f(x)dx with Simpson's 1/3 rule. Just enter f(x), the interval, and an even number of subdivisions.

Approximate the definite integral of f(x) using the trapezoidal rule. Split [a, b] into n subintervals and view the result, step size, and each sample point.

Enter the right-hand side of dy/dx=f(x,y) plus the initial values x0 and y0, the step size h, and the end point xEnd to solve the ODE numerically with the classic 4th-order Runge-Kutta method (RK4). Shows the approximate solution y at the end point, a table of k1–k4 and y at each step, and a graph of the solution curve.