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Swimming Maths

Maths in swimming: personal bests

Find how many seconds faster a swim became.

Quick answer

Maths in swimming: personal bests helps you find how many seconds faster a swim became by subtracting the new time from the old time.

Learning outcome

By the end of this page, you will be able to calculate how much faster (or slower) your swimming time is compared to your last swim, using subtraction. Success signs:
  • You can subtract two times to find the difference
  • You understand that a smaller time means you swam faster
  • You can use a number line or subtraction to find how much faster you got
  • You can compare your swimming times and say if you improved

Why this matters

When you swim, you might want to know if you’re getting faster or slower. If you swim 50 metres and your time is 45 seconds, and the next time you swim 50 metres it's 42 seconds, you've improved by 3 seconds. That's a personal best! This maths helps you track your progress, set goals, and feel proud of your improvement. Whether you're swimming in a pool, at the beach, or just in your backyard, you can use maths to see how much faster you are. This helps you see your progress and makes swimming more fun when you're getting better.

How it works

To find how much faster you became, follow these steps:
  1. Write down your old swimming time
  2. Write down your new swimming time
  3. Subtract the new time from the old time
  4. If the answer is positive, you got faster
  5. If the answer is negative, you got slower
For example:
  • Old time: 50 seconds
  • New time: 46 seconds
  • 50 - 46 = 4 seconds faster

Examples you can see

Let’s look at some real swimming examples. Example 1: A child swimming 100 metres
  • Last week: 1 minute 30 seconds
  • This week: 1 minute 20 seconds
First, convert to seconds:
  • 1 min 30 sec = 60 + 30 = 90 seconds
  • 1 min 20 sec = 60 + 20 = 80 seconds
Then subtract:
  • 90 - 80 = 10 seconds faster
Example 2: A swimmer improving
  • Old time: 1 minute 15 seconds
  • New time: 1 minute 10 seconds
Convert to seconds:
  • 1 min 15 sec = 60 + 15 = 75 seconds
  • 1 min 10 sec = 60 + 10 = 70 seconds
Subtract:
  • 75 - 70 = 5 seconds faster
Example 3: A slower swim
  • Old time: 55 seconds
  • New time: 1 minute 10 seconds
Convert:
  • 1 min 10 sec = 60 + 10 = 70 seconds
Subtract:
  • 70 - 55 = 15 seconds slower

Try it as a mini adventure

Swimming Challenge: Personal Best Quest You are a swimmer on a quest to find your personal best time! Every week you swim 50 metres and record your time. Week 1: 45 seconds Week 2: 42 seconds Week 3: 40 seconds Week 4: 43 seconds Week 5: 38 seconds Your mission: Find how much faster you got each week compared to the previous week. Week 1 to Week 2: 45 - 42 = 3 seconds faster Week 2 to Week 3: 42 - 40 = 2 seconds faster Week 3 to Week 4: 43 - 40 = 3 seconds slower Week 4 to Week 5: 43 - 38 = 5 seconds faster You improved a lot! Your fastest time was in Week 5. You were 5 seconds faster than the week before. Now, you can track your personal bests and see your progress.

Common mistakes

  • Mistake: Subtracting the old time from the new time instead of the new from the old.
    Why: This gives a negative number, which can be confusing.
    Fix: Always subtract the new time from the old time to see how much faster you got.
  • Mistake: Forgetting to convert minutes to seconds.
    Why: It's easier to subtract when everything is in the same unit.
    Fix: Remember that 1 minute = 60 seconds. Add 60 seconds for every minute.
  • Mistake: Thinking that a bigger number means you got faster.
    Why: Time is measured from start to finish. The shorter the time, the faster you are.
    Fix: The smaller the number, the faster you are!

Parent and carer guide

As a parent or carer, you can help your child understand swimming times and personal bests in a few minutes:
  • Ask your child to record their swimming times each week.
  • Help them convert minutes to seconds if needed.
  • Use a number line to show how much time was saved.
  • Encourage them to celebrate when they beat their personal best.
  • Play a game: “Who can swim 50 metres faster?”
If your child gets confused:
  • Ask them to explain their thinking
  • Use physical examples like counting blocks or drawing a line
  • Don’t worry if they make a mistake — it’s part of learning

Practice questions

  1. Old time: 1 minute 20 seconds. New time: 1 minute 15 seconds. How much faster?
  2. Old time: 40 seconds. New time: 37 seconds. How much faster?
  3. Old time: 1 minute 10 seconds. New time: 1 minute 15 seconds. How much slower?
  4. Old time: 55 seconds. New time: 50 seconds. How much faster?
  5. Old time: 1 minute 5 seconds. New time: 1 minute 2 seconds. How much faster?
Answers:
  1. 5 seconds faster
  2. 3 seconds faster
  3. 5 seconds slower
  4. 5 seconds faster
  5. 3 seconds faster

FAQ

What is a personal best in swimming?

A personal best is the fastest time you’ve ever swum a certain distance. It’s your own record!

How do I know if I got faster?

If your new time is smaller than your old time, you got faster. If it’s bigger, you got slower.

Can I use this maths for other sports?

Yes! You can use this same subtraction idea for running, cycling, or any timed activity.

Why do I need to convert minutes to seconds?

It makes subtraction easier and more accurate. When everything is in seconds, it’s like counting apples — you can compare them easily.

How can I track my swimming progress?

Record your times each week and subtract to see how much faster you got. You can make a chart or use a notebook to keep track!