Elapsed Time Calculator

How to use the elapsed time calculator

1. Under Hours between two times, type when something began into Start time. Shorthand works: 9 is 9:00 AM, 5p is 5:00 PM, 1730 is 5:30 PM.
2. Type when it finished into End time. The elapsed time appears as hours and minutes with the decimal figure beside it, refreshing with every keystroke.
3. An end earlier on the clock face than the start is treated as the following morning and the result carries an Overnight tag.
4. If part of the span should not count, such as a 20-minute rest stop on a drive, put those minutes in Break (minutes).
5. For the other direction, go to Add or subtract time, enter a clock time in Start from, choose Add or Subtract, then fill in Hours and Minutes.
6. The resulting clock time appears under those boxes, marked next day or previous day when it passes through midnight.

Counting up, the way it is taught in school

An elapsed time calculator and a time duration calculator answer the same question: how much time passed between two clock readings. Elapsed time word problems in grades 3 to 5 are solved by counting up in three moves: reach the next full hour, jump whole hours, then add the leftover minutes. Say soccer practice runs from 3:50 PM to 5:35 PM. From 3:50 to 4:00 is 10 minutes, 4:00 to 5:00 is 1 hour, and 5:00 to 5:35 is 35 minutes. Together that is 1 hour 45 minutes. Teachers often lay this out as a T-chart:

The other classroom method is column subtraction with regrouping. In 5:35 minus 3:50 the minutes will not subtract, since 35 is smaller than 50, so borrow one hour and add 60 to the minutes: 4:95 minus 3:50 equals 1:45. Type 3:50p and 5:35p into the tool to check either method.

Crossing noon and crossing midnight

The 12-hour clock restarts twice a day, and both restarts cause errors. A road trip leg from 10:35 AM to 1:10 PM cannot be found by subtracting 10:35 from 1:10, which gives a negative number. Count up instead: 25 minutes to 11:00, one hour to noon, one more to 1:00 PM, then 10 minutes, for 2 hours 35 minutes. An end time typed without AM or PM is read as the first matching time after the start, so 10:35 to 1:10 returns 2:35 without extra typing.

Midnight is different, because a start time typed without a suffix is read as morning. A brisket goes into the smoker at 9:20 PM and comes out at 7:05 AM. Split the span at midnight: 9:20 PM to 12:00 AM is 2 hours 40 minutes, and 12:00 AM to 7:05 AM is 7 hours 5 minutes, so it cooked for 9 hours 45 minutes. Type the start as 9:20p. A bare 9:20 is taken as 9:20 AM, which pushes the 7:05 AM finish to the next morning and reports 21:45 with an Overnight tag. A tag you did not expect means an AM or PM got dropped.

Finding an end time or a start time

When the elapsed time is known and the clock time is not, use the Add or subtract time section. A roast that needs 2 hours 25 minutes and goes in the oven at 4:50 PM comes out at 7:15 PM: add 2 hours to reach 6:50 PM, then 25 minutes. A parking meter fed at 11:40 AM for 2 hours 30 minutes runs out at 2:10 PM, since 11:40 plus 2 hours is 1:40 PM and 30 more minutes lands on 2:10.

Working backward uses Subtract. A movie that lets out at 9:50 PM and runs 2 hours 15 minutes started at 7:35 PM. When the answer lands on a different date, as when 3 hours come off 1:30 AM to give 10:30 PM, the result is marked previous day.

Hours and minutes versus decimal hours

Elapsed time is spoken in hours and minutes, but the decimal figure beside the result is the one you multiply with. The road trip leg of 2 hours 35 minutes is 2 + 35 / 60 = 2.58 hours, and the 1 hour 45 minute practice is 1.75 hours. Decimals make rate questions direct: 155 miles in 2 hours 35 minutes is 155 miles in 155 minutes, one mile per minute, or 60 miles per hour. The rules for moving between the two forms are on the decimal hours calculator; if the span is a paid shift, the hours calculator covers the payroll side. To add several elapsed times together, use the hours and minutes calculator.

Frequently asked questions