Other

Estimate the cooling or heating needs of your room or house with our BTU calculator. Calculate exact requirements based on size, insulation, and climate.

Estimate the volume and weight of concrete needed for slabs, columns, stairs, and more. Get precise bag counts and truck delivery estimates.

Calculate how much gravel you need for a driveway or path in cubic yards, cubic feet, and tons.

Add up the R-values of your wall or ceiling assembly's layers to find its total R-value, then estimate heat loss for a given area and temperature difference.

Calculate how much mulch you need for your garden beds in cubic yards, cubic feet, and standard 2 cu ft bags.

Calculate how many gallons of paint you need for a room based on its dimensions, number of coats, and paint coverage per gallon.

Calculate how many gallons your pool holds from its dimensions -- supports rectangular and circular/round pools.

Accurately estimate your total roof area and the necessary amount of materials needed, including roofing squares, bundles of shingles, and recommended overage.

Accurately estimate the square footage and total cost of materials for a variety of common shapes, including rectangles, circles, triangles, and more.

Accurately calculate the exact dimensions for stairs including total run, stringer length, number of steps, and angle of inclination.

Estimate the total number of tiles necessary to cover a floor, roof, or wall, including calculations for grout gaps, overlaps, and total box costs.

Estimate the cost of charging your electric vehicle from your battery size, charge level, and electricity rate -- and compare the cost per mile against a gas car.

Estimate the fuel needed and total cost for a trip based on distance, fuel efficiency, and price per gallon or liter.

Calculate your vehicle's fuel efficiency (MPG or L/100km) from the distance traveled and fuel used, plus your cost per mile or kilometer.

Estimate engine horsepower two ways — from quarter-mile trap speed and vehicle weight, or from torque and engine RPM.

Calculate your mileage reimbursement or tax deduction using the standard mileage rate for business, medical, moving, or charitable driving.

Calculate speed from distance and time, with instant results in mph, km/h, m/s, and knots.

Compare two tire sizes (e.g. 225/50R17) to see the difference in diameter, circumference, revolutions per mile, and speedometer accuracy.

Calculate density from mass and volume, with instant results in kg/m³, g/cm³, and lb/ft³.

Estimate the energy consumption and running cost of any electrical appliance based on its wattage, daily usage, and your electricity rate.

Convert mass between milligrams, grams, kilograms, metric tons, ounces, pounds, stone, and US tons instantly.

Calculate the molarity of a solution from solute mass, molar mass, and solution volume — a core calculation for chemistry lab work.

Calculate the molecular weight (molar mass) of any chemical formula, including compounds with parentheses like Ca(OH)2.

Solve for voltage, current, resistance, or power using Ohm's Law — enter any two known values and calculate the rest.

Decode 4-band or 5-band resistor color codes into resistance value and tolerance, instantly and accurately.

Estimate how many years it takes for a home solar panel system to pay for itself through electricity bill savings, and project 25-year lifetime savings.

Calculate voltage drop and percentage drop across a wire run based on wire gauge, material, distance, current, and circuit voltage.

Convert weight between kilograms and pounds, and see what you'd weigh on the Moon, Mars, Jupiter, and other planets based on their gravity.

Calculate the dew point from air temperature and relative humidity using the Magnus formula, and see how muggy it will actually feel.

Calculate the heat index — the "feels like" temperature from air temperature and relative humidity — using the NWS Rothfusz regression.

Calculate wind chill — the "feels like" temperature from wind speed and air temperature — using the official NWS formula.

Count the number of days between two dates or calculate a future/past date. Includes options for business days, weekends, and holidays.

Find the day of the week for any historical or future date. Discover fascinating trivia and facts about every day of the week.

Calculate the exact number of hours and minutes between two times or two dates with our free, online Hours Calculator.

Find the best bedtime or wake-up time based on 90-minute sleep cycles, so you wake up feeling rested instead of groggy.

Calculate the exact time difference between two times or dates. Get results in hours, minutes, and seconds with our precise duration tool.

Roll virtual dice online — choose the number of dice and sides (d4 to d100) and get instant results with the total.

Free Female Delusion Calculator: enter minimum height, income, and age standards and see what percentage of U.S. men meet all three, based on published population statistics.

Calculate Gross Domestic Product (GDP) using the expenditure approach — consumption, investment, government spending, and net exports.

Calculate your golf score differential from your score, course rating, and slope rating — the building block of the USGA Handicap Index.

Convert height between feet and inches, centimeters, and meters instantly, in either direction.

Free Male Delusion Calculator: enter maximum BMI and age standards and see what percentage of U.S. women meet both, based on published population statistics.

Convert numbers to Roman numerals or Roman numerals back to numbers, instantly and accurately, for values from 1 to 3,999.

Convert shoe sizes between US Men's, US Women's, UK, EU, and foot length in centimeters — a handy reference for international shopping.

Calculate the tip amount, total bill, and per-person split for any bill amount and tip percentage.