Ctrl+k

Calculate elapsed time

Elapsed time is the duration between a start time and an end time, determined by decomposing and combining hours and minutes, converting between these units, and accounting for hour, noon, or midnight boundaries. Students interpret clock times on timelines, analog or digital displays, and 12- or 24-hour notation rather than subtracting clock readings as ordinary base-ten numbers; this reasoning supports later work with schedules, rates, and time-based measurement, without extending to time zones or advanced rate calculations.

Detailed Explanation: Calculate elapsed time

Elapsed time is the amount of time from a start time to an end time. Instead of subtracting the clock numbers as ordinary numbers, move forward along a timeline.

Example: A class starts at 10:45 AM and ends at 1:20 PM. How long is the class?

  1. Move from 10:45 AM to 11:00 AM:
    1515 minutes

  2. Move from 11:00 AM to 12:00 PM:
    11 hour

  3. Move from 12:00 PM to 1:00 PM:
    11 hour

  4. Move from 1:00 PM to 1:20 PM:
    2020 minutes

Combine the hours and minutes:

1 hour+1 hour=2 hours1\text{ hour}+1\text{ hour}=2\text{ hours} 15 minutes+20 minutes=35 minutes15\text{ minutes}+20\text{ minutes}=35\text{ minutes}

So, the elapsed time is:

2 hours 35 minutes\boxed{2\text{ hours }35\text{ minutes}}

Notice that the time passes through noon, so the labels change from AM to PM. A timeline helps keep the order clear.

Learn by doing: Calculate elapsed time

Click a topic below to practice the foundational skills you'll need, learn the steps, or master this skill

    Practice with unlimited practice problems

    Time - Elapsed - Two Times To Hours & Minutes - Quarter Hours

      ?