CalculatorsHelpDate Time Calculator The Date Time Calculator is used to perform basic date and time operations where you can add, subtract and find the duration between two dates and times. You just have to pick the right operation type and enter the date and time. There are also separate calculators built for in depth functionalities - Date Calculator and Time Calculator. 🗓️ Date Time Calculator⚙️ Operation TypeAddSubtractDuration BetweenStart DateStart Time ➕ YearsMonthsWeeksDaysHours:Minutes:Seconds:MillisecondsMS Calculate Clear 📅 DateSeptember 15, 2025⌚ Time08:13 am What is the date when you add year, month, week, day, hour, minute, second, millisecond starting from September 15, 2025? The answer is September 15, 2025 08:13 am. How to Use the Date Time Calculator There are instances that you really need help from counting-off days, or finding what's the entire duration between two date and times. These things are much better solved using this Date Time Calculator than doing them manually. For example, you want to know how many days are there starting from January 1, 2023 with the current local time and December 24, 2024 at exactly 12:00 midnight. With this calculator, you'll have the exact details you are looking for. The calculator is grouped into three (3) parts, the first set is marked with ⚙️ Operation Type where you can select the operation you want to perform (functionality). The second set is the main one where there's input fields and buttons. The third is the result area where it displays the outcome of the calculations. Add Date and Time Usage Here's a step by step guide on how to use the Data and Time Calculator in order to Add Date and Time: Step 1 On the topmost part of the calculator, you can find the ⚙️ Operation Type field set. It is where you need to choose from the operation options - add, subtract and duration between. If you want to add days, weeks, months and/or years, select the add radio button. Step 2 After you have chosen the Add operation (which is selected by default), you'll get to enter the Start Date and Start Time. This date and time servers as a reference when we add the days, months, etc. Let's make an example, enter January 1, 2022 as start date and 06:00 AM as start time. Step 3 When you have entered the Start Date and Start Time, you can now enter the days, months, weeks, days, hours, minutes, seconds and milliseconds that you want to be added to the start date and time. You can choose the leave inputs blank if you don't need them. Continuing our example on step 2, let's add 4 months, 6 days and 10 hours. Step 4 The final step for adding date and time is to click the Calculate button. The results will be displayed below the buttons. You can click the Clear button to reset the input fields. Following our example so far, the answer should be May 7, 2022 at 04:00 PM. Subtract Date and Time Usage Here's a step by step guide on how to use the Data and Time Calculator in order to Subtract Date and Time: Step 1 On the ⚙️ Operation Type field set, click on the Subtract radio button for we want to subtract days, months and time from a start date and time. Step 2 The change to subtract operation type is confirmed by the visibility of subtract (➖) sign. What you need to do now is to enter the Start Date and/or Start Time. It's best to give an example inputs here, let's enter February 15, 2022 as start date and 12:00 AM as start time. Step 3 After you have entered the Start Date and Time, you can now enter the days, weeks, months, years, hours, minutes, seconds and milliseconds that you want to subtract from the reference date and time. For the fields that are not needed, you can just leave them blank. Continuing our example on step 2, let's subtract 7 years, 3 weeks, 5 days and 6 hours. Step 4 The final step for adding date and time is to click the Calculate button. The results will be displayed below the buttons. You can click the Clear button to reset the input fields. Following our example, the answer should be January 19, 2015 at 06:00 PM. Duration Between Date and Time Usage Here's a step by step guide on how to use the Data and Time Calculator in order to Duration Between Date and Time: Step 1 On the ⚙️ Operation Type field set, click on the Duration Between radio button for we want to get the entire duration between from the start date and time to the end date and time. Step 2 The duration between operation type is confirmed by arrow sign (⇢). What you need to do now is to enter the Start Date and/or Start Time. Let's try entering March 1, 2022 as start date and 3:00 PM as start time. Step 3 Then, enter the End Date and End Time on their corresponding date and time input fields. They are labeled so that it will be easier for you to distinguish them. Continuing with our example, let's enter December 25, 2022 as end date and 12:00 AM as end time. Step 4 The final step for adding date and time is to click the Calculate button. The results will be displayed below the buttons. You can click the Clear button to reset the input fields. For our previous example inputs, the answer should be 9 months, 3 weeks and 2 days. All other totaled minutes, hours, days, etc. should also be displayed. Video ExplanationHere's a video tutorial on how to use the Date Time Calculator.Related Calculators: © 2022 - 2025 , Use this time and date duration calculator to find out the number of days, hours, minutes, and seconds between the times on two different dates. To add or subtract time from a date, use the Time Calculator., Weekday Calculator – What Day is this Date? – Find the weekday for any date. The Date Calculator adds or subtracts days, weeks, months and years from a given date..