Time Calculator - Add, Subtract & Convert Time Units Online Free
Time Calculator - Add, subtract, and convert time instantly. Calculate durations, convert units, and plan your schedule efficiently.
Add or Subtract Time
Date + Time Calculator
Time Unit Converter
Expression Calculator
Understanding Time Calculation
What is a Time Calculator?
A time calculator is a digital tool that performs arithmetic operations on time values. Unlike standard calculators that work with decimal numbers, time calculators handle the sexagesimal (base-60) system used for measuring time.
This is essential because time units don't convert simply: 60 seconds = 1 minute, 60 minutes = 1 hour, but 24 hours = 1 day. Our calculator handles all these conversions automatically, making complex time calculations effortless.
How Time is Measured
Time measurement is based on the sexagesimal (base-60) numeral system, originated from ancient Sumer in the 3rd millennium BC. This system was adopted by the Babylonians and is still used today for measuring time and angles.
- • 1 day = 24 hours = 1,440 minutes = 86,400 seconds
- • 1 hour = 60 minutes = 3,600 seconds
- • 1 week = 7 days = 168 hours
- • 1 month (avg) ≈ 30.4 days ≈ 730 hours
Practical Applications
Project Management
Calculate total project hours, estimate completion dates, and track time across multiple tasks. Convert between work days and calendar days for accurate planning.
Travel Planning
Calculate flight durations, layover times, and arrival times across time zones. Plan itineraries with accurate time calculations for better trip organization.
Cooking & Timing
Add cooking times for multiple dishes, calculate preparation schedules, and plan meal timing to ensure everything is ready simultaneously.
Fitness Training
Track workout durations, rest periods, and training intervals. Calculate total exercise time and plan workout schedules with precision.
Work Hours Tracking
Calculate billable hours, track overtime, and compute payroll time. Subtract lunch breaks and convert to work days for accurate reporting.
Time Management
Use Pomodoro technique calculations, plan focused work sessions, and balance work-rest ratios for optimal productivity.
Time Management Best Practices
The Pomodoro Technique
Work in 25-minute focused intervals (Pomodoros) followed by 5-minute breaks. After 4 Pomodoros, take a longer 15-30 minute break. This technique improves focus and prevents burnout.
Example: An 8-hour workday = 16 Pomodoros = 6h 40m focused work + 1h 20m breaks
Time Blocking
Divide your day into blocks of time, each dedicated to specific tasks or activities. Calculate block durations to ensure balanced time allocation across priorities.
Recommended Split: 8 hours work, 8 hours personal time, 8 hours sleep
Peak Productivity Hours
Most people experience peak cognitive performance during specific hours. Schedule demanding tasks during your peak hours (typically 9am-12pm and 2pm-5pm) and routine tasks during lower-energy periods.
Frequently Asked Questions
How do I add time in the calculator?
To add time: 1) Select 'Add/Subtract' mode, 2) Enter Time 1 values (days, hours, minutes, seconds), 3) Click 'Add (+)' button, 4) Enter Time 2 values, 5) The result displays automatically. Example: 2d 5h 30m + 1d 3h 45m = 3d 9h 15m.
What is the time unit converter?
The time unit converter allows you to convert between seconds, minutes, hours, and days instantly. Enter a value, select the unit (e.g., 10000 seconds), and see it converted to all other units: 2h 46m 40s, 166.67 minutes, 0.11 days, and 10,000,000 milliseconds.
How does the expression calculator work?
The expression calculator allows complex time calculations using text format. Use 'd' for days, 'h' for hours, 'm' for minutes, 's' for seconds. Example: '2d 5h 30m + 3h 45m - 1h 15m' calculates to 2 days, 8 hours, 0 minutes. Use + and - operators freely.
How do I clear the calculator inputs?
Each calculator mode has a 'Clear' button in the top-right corner. Click it to instantly reset all input fields to blank, allowing you to start a new calculation quickly.
Can I calculate time across different dates?
Yes! Use the 'Date + Time' mode. Select a start date and time, choose Add or Subtract, enter a duration (days, hours, minutes), and see the resulting date and time. Perfect for planning deadlines, scheduling events, or calculating project timelines.
Why are there four separate calculators?
Each calculator serves a different purpose: Add/Subtract for basic time operations, Date+Time for calendar-based calculations, Converter for unit conversions, and Expression for complex formulas. All four are displayed vertically for easy access without switching tabs.
How accurate is the time calculator?
The time calculator is 100% accurate for all calculations. It converts all inputs to seconds, performs calculations, then converts back to days, hours, minutes, and seconds. Results are precise down to the second level.
Is my data saved or stored?
No. All calculations are performed entirely in your browser using JavaScript. No data is sent to servers or stored anywhere. Your calculations remain private and are cleared when you close the browser tab.