Free everyday utility calculators for dates, time, education, construction, and more. Simple tools that make life easier.
47 free calculators organized by category
Calculate dates, times, and durations
Calculate exact age in years, months, and days between two dates.
Add or subtract days, weeks, months, or years from any date.
Add or subtract hours, minutes, and seconds. Convert between time formats.
Calculate total work hours and time between two times.
Calculate total hours for timesheets and payroll.
Convert time between different time zones worldwide.
Calculate duration between two times or dates.
Count the number of days between two dates.
Find what day of the week any date falls on.
Find the best time to sleep or wake up based on sleep cycles.
Academic calculators for students
Calculate your GPA based on grades and credit hours. Supports different grading scales.
Calculate course grades and weighted averages for assignments.
Estimate total college costs including tuition and expenses.
Calculate materials and measurements for building projects
Calculate concrete needed for slabs, footings, columns, and stairs.
Calculate area for rooms, flooring, and construction projects.
Calculate stair dimensions including rise, run, and stringers.
Calculate roofing materials needed for your project.
Calculate number of tiles needed for flooring or walls.
Calculate mulch needed for landscaping projects.
Calculate gravel or aggregate needed for projects.
Electrical and network calculators
Calculate voltage drop for wire sizing and electrical projects.
Calculate resistance values and color codes for resistors.
Calculate voltage, current, resistance using Ohms Law (V=IR).
Calculate electricity costs and energy consumption for appliances.
Calculate heating and cooling requirements in BTUs.
Calculate network bandwidth requirements and speeds.
Calculate IP address ranges and subnet masks.
Vehicle-related calculators
Calculate fuel costs for trips based on distance and fuel prices.
Calculate fuel efficiency and MPG for vehicles.
Calculate travel distance and mileage for trips.
Calculate engine horsepower and performance metrics.
Compare tire sizes and calculate speedometer differences.
Weather and temperature calculators
Calculate apparent temperature based on wind speed and temperature.
Calculate heat index based on temperature and humidity.
Calculate dew point from temperature and humidity.
Scientific calculators for physics and chemistry
Calculate density from mass and volume.
Calculate speed, velocity, distance, or time.
Calculate mass from density and volume.
Calculate molarity and solution concentrations.
Calculate molecular weight of chemical compounds.
Everyday life calculators and tools
Calculate tips and split bills easily. Includes preset tip percentages.
Convert height between feet/inches and centimeters.
Convert shoe sizes between US, UK, EU, and other systems.
Calculate proper bra size from measurements.
Generate secure random passwords with customizable settings.
Roll virtual dice for games and random number generation.
Calculate your golf handicap index from recent scores.
Quick calculations without searching for formulas or downloading apps.
Reliable calculations you can trust for important decisions.
Works on any device with a web browser. No installation needed.