Source: https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/6-2-2-changing-the-12-hour-clock-to-the-24-hour-clock

[Revision notes](https://senecalearning.com/en-gb/revision-notes.md) › [Primary](https://senecalearning.com/en-gb/revision-notes/primary.md) › [Maths](https://senecalearning.com/en-gb/revision-notes/primary/maths.md) › [Maths: Year 3 & 4 National Curriculum](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum.md) › Changing the 12-Hour Clock to the 24-Hour Clock

# Changing the 12-Hour Clock to the 24-Hour Clock

Maths: Year 3 & 4 National Curriculum, topic 6.2.2

## Changing from the 12-Hour to the 24-Hour Clock

You may be asked to convert a time from the 12-hour clock to the 24-hour clock.

### Example problem

![Example problem](https://image-v2.cdn.app.senecalearning.com/2019-04/76b7824c-2963-4f64-9aae-6ccc845f3344/clock%20(8).png)

- What is 6.30pm in the 24-hour clock?

### Change to the 24-hour clock

![Change to the 24-hour clock](https://image-v2.cdn.app.senecalearning.com/2019-04/76b7824c-2963-4f64-9aae-6ccc845f3344/clock%20(8).png)

- 6.30pm is in the afternoon, so we need to add 12 to the first number to get the time in the 24-hour clock.
 - 6 + 12 = 18
    - So 6.30pm is 18.30 in the 24-hour clock.

### Example problem

![Example problem](https://image-v2.cdn.app.senecalearning.com/2019-04/319537d8-bb66-42dd-be06-6269078752b4/clock%20(11).png)

- What is 8.45am in the 24-hour clock?

### Change to the 24-hour clock

![Change to the 24-hour clock](https://image-v2.cdn.app.senecalearning.com/2019-04/319537d8-bb66-42dd-be06-6269078752b4/clock%20(11).png)

- 8.45am is in the morning, so the hourly time stays the same in the 24-hour clock.
 - 8.45am is 08.45 in the 24-hour clock.

### What about 12am?

![What about 12am?](https://image-v2.cdn.app.senecalearning.com/2019-06/197ad1ec-b681-492d-86fa-c837f1a08815/midnight-12-.png)

- 12am is written as 00.00 in the 24-hour clock.
 - So 12.59am would be 00.59 in the 24-hour clock.

## Test yourself on Changing the 12-Hour Clock to the 24-Hour Clock

- What's 3pm in the 24-hour clock?
- What's 1.04am in the 24-hour clock?
- Your train is scheduled to leave at 3.15pm.What time is this in the 24-hour clock?
- Sheila is going horse riding at 8.30am.What time is this in the 24-hour clock?

[Practise this topic for free](https://app.senecalearning.com/classroom/course/b3e638ef-6270-4a25-af8f-e836c0245e36/section/a0bf52a0-5a8e-4312-9796-840bc061ccd2/session)

- Previous topic: [6.2.1 Converting Units of Time](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/6-2-1-converting-units-of-time.md)
- Next topic: [6.2.3 Changing the 24-hour Clock to the 12-Hour Clock](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/6-2-3-changing-the-24-hour-clock-to-the-12-hour-clock.md)

## Maths: Year 3 & 4 National Curriculum contents

### 1 Year 3 - Number
- 1.1 Number & Place Value
  - [1.1.1 Multiples](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-1-1-multiples.md)
  - [1.1.2 Counting in Multiples](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-1-2-counting-in-multiples.md)
  - [1.1.3 Recognising Three-Digit Numbers](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-1-3-recognising-three-digit-numbers.md)
  - [1.1.4 Finding 10 More or Less than a Number](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-1-4-finding-10-more-or-less-than-a-number.md)
  - [1.1.5 Finding 100 More or Less than a Number](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-1-5-finding-100-more-or-less-than-a-number.md)
  - [1.1.6 Ordering & Comparing Numbers up to 1,000](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-1-6-ordering-and-comparing-numbers-up-to-1000.md)
  - [1.1.7 Writing & Reading Numbers](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-1-7-writing-and-reading-numbers.md)
  - [1.1.8 Representing Numbers](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-1-8-representing-numbers.md)
- 1.2 Addition & Subtraction
  - [1.2.1 Mental Addition & Subtraction](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-2-1-mental-addition-and-subtraction.md)
  - [1.2.2 Column Method](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-2-2-column-method.md)
  - [1.2.3 Estimating Calculations](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-2-3-estimating-calculations.md)
  - [1.2.4 Inverse Operations](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-2-4-inverse-operations.md)
  - [1.2.5 Missing Number Problems](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-2-5-missing-number-problems.md)
  - [1.2.6 Real-Life Problems](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-2-6-real-life-problems.md)
- 1.3 Multiplication & Division
  - [1.3.1 Times Tables](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-3-1-times-tables.md)
  - [1.3.2 Using Times Tables](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-3-2-using-times-tables.md)
  - [1.3.3 Multiplying Numbers](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-3-3-multiplying-numbers.md)
  - [1.3.4 Missing Number Problems](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-3-4-missing-number-problems.md)
  - [1.3.5 Real-Life Problems](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-3-5-real-life-problems.md)
- 1.4 Fractions
  - [1.4.1 Tenths](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-4-1-tenths.md)
  - [1.4.2 Fractions](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-4-2-fractions.md)
  - [1.4.3 Fractions Equal to a Whole](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-4-3-fractions-equal-to-a-whole.md)
  - [1.4.4 Equivalent Fractions](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-4-4-equivalent-fractions.md)
  - [1.4.5 Fractions of Shapes](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-4-5-fractions-of-shapes.md)
  - [1.4.6 Fractions of Amounts](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-4-6-fractions-of-amounts.md)
  - [1.4.7 Add & Subtract Fractions](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-4-7-add-and-subtract-fractions.md)
  - [1.4.8 Compare & Order Fractions](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/1-4-8-compare-and-order-fractions.md)

### 2 Year 3 - Measurement
- 2.1 Length
  - [2.1.1 Length](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-1-1-length.md)
  - [2.1.2 Comparing Lengths](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-1-2-comparing-lengths.md)
  - [2.1.3 Add & Subtract Lengths](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-1-3-add-and-subtract-lengths.md)
  - [2.1.4 Perimeter](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-1-4-perimeter.md)
- 2.2 Mass
  - [2.2.1 Mass](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-2-1-mass.md)
  - [2.2.2 Comparing Masses](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-2-2-comparing-masses.md)
  - [2.2.3 Add & Subtract Masses](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-2-3-add-and-subtract-masses.md)
- 2.3 Volume & Capacity
  - [2.3.1 Volume & Capacity](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-3-1-volume-and-capacity.md)
  - [2.3.2 Comparing Volumes](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-3-2-comparing-volumes.md)
  - [2.3.3 Add & Subtract Volumes](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-3-3-add-and-subtract-volumes.md)
- 2.4 Money
  - [2.4.1 Money](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-4-1-money.md)
  - [2.4.2 Counting Money](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-4-2-counting-money.md)
  - [2.4.3 Adding & Subtracting Money](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-4-3-adding-and-subtracting-money.md)
- 2.5 Time
  - [2.5.1 Units of Time](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-5-1-units-of-time.md)
  - [2.5.2 Clocks](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-5-2-clocks.md)
  - [2.5.3 Telling the Time](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-5-3-telling-the-time.md)
  - [2.5.4 Time of the Day](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-5-4-time-of-the-day.md)
  - [2.5.5 12-Hour & 24-Hour Clocks](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-5-5-12-hour-and-24-hour-clocks.md)
  - [2.5.6 Measuring Time](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/2-5-6-measuring-time.md)

### 3 Year 3 - Geometry
- 3.1 Angles
  - [3.1.1 Angles in Degrees](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/3-1-1-angles-in-degrees.md)
  - [3.1.2 Types of Angle](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/3-1-2-types-of-angle.md)
- 3.2 Properties of Shapes
  - [3.2.1 2D Shapes](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/3-2-1-2d-shapes.md)
  - [3.2.2 3D Shapes](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/3-2-2-3d-shapes.md)
- 3.3 Straight Lines
  - [3.3.1 Straight Lines](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/3-3-1-straight-lines.md)
  - [3.3.2 Parallel & Perpendicular Lines](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/3-3-2-parallel-and-perpendicular-lines.md)

### 4 Year 3 - Statistics
- 4.1 Statistics
  - [4.1.1 Statistics](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/4-1-1-statistics.md)
  - [4.1.2 Pictograms & Bar Charts](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/4-1-2-pictograms-and-bar-charts.md)

### 5 Year 4 - Number
- 5.1 Number & Place Value
  - [5.1.1 Counting in Multiples](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-1-1-counting-in-multiples.md)
  - [5.1.2 Recognising Four Digit Numbers](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-1-2-recognising-four-digit-numbers.md)
  - [5.1.3 Find 1,000 More or Less than a Number](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-1-3-find-1000-more-or-less-than-a-number.md)
  - [5.1.4 Negative Numbers](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-1-4-negative-numbers.md)
  - [5.1.5 Ordering & Comparing Numbers Over 1,000](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-1-5-ordering-and-comparing-numbers-over-1000.md)
  - [5.1.6 Representing Numbers](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-1-6-representing-numbers.md)
  - [5.1.7 Rounding Numbers](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-1-7-rounding-numbers.md)
  - [5.1.8 Roman Numerals](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-1-8-roman-numerals.md)
- 5.2 Addition & Subtraction
  - [5.2.1 Written Methods for Adding Large Numbers](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-2-1-written-methods-for-adding-large-numbers.md)
  - [5.2.2 Written Methods for Subtracting Large Numbers](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-2-2-written-methods-for-subtracting-large-numbers.md)
  - [5.2.3 Estimation & Inverse Operations](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-2-3-estimation-and-inverse-operations.md)
  - [5.2.4 Solving Two-Step Problems](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-2-4-solving-two-step-problems.md)
- 5.3 Multiplication & Division
  - [5.3.1 Times Tables](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-3-1-times-tables.md)
  - [5.3.2 Using Times Tables](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-3-2-using-times-tables.md)
  - [5.3.3 Multiplication Rules](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-3-3-multiplication-rules.md)
  - [5.3.4 Column Method](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-3-4-column-method.md)
  - [5.3.5 Factors](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-3-5-factors.md)
- 5.4 Fractions & Decimals
  - [5.4.1 Identifying Equivalent Fractions](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-4-1-identifying-equivalent-fractions.md)
  - [5.4.2 Adding & Subtracting Fractions](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-4-2-adding-and-subtracting-fractions.md)
  - [5.4.3 Hundredths](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-4-3-hundredths.md)
  - [5.4.4 Decimals](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-4-4-decimals.md)
  - [5.4.5 Converting Between Decimals & Fractions](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-4-5-converting-between-decimals-and-fractions.md)
  - [5.4.6 Rounding Decimals](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-4-6-rounding-decimals.md)
  - [5.4.7 Ordering Decimals](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/5-4-7-ordering-decimals.md)

### 6 Year 4 - Measurement
- 6.1 Units
  - [6.1.1 Metric Measurements](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/6-1-1-metric-measurements.md)
  - [6.1.2 Adding & Subtracting Money](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/6-1-2-adding-and-subtracting-money.md)
- 6.2 Time
  - [6.2.1 Converting Units of Time](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/6-2-1-converting-units-of-time.md)
  - [6.2.2 Changing the 12-Hour Clock to the 24-Hour Clock](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/6-2-2-changing-the-12-hour-clock-to-the-24-hour-clock.md)
  - [6.2.3 Changing the 24-hour Clock to the 12-Hour Clock](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/6-2-3-changing-the-24-hour-clock-to-the-12-hour-clock.md)

### 7 Year 4 - Geometry
- 7.1 Properties of Shapes
  - [7.1.1 Symmetry](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/7-1-1-symmetry.md)
  - [7.1.2 Types of Triangle](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/7-1-2-types-of-triangle.md)
  - [7.1.3 Quadrilaterals](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/7-1-3-quadrilaterals.md)
- 7.2 Perimeter & Area
  - [7.2.1 Perimeter](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/7-2-1-perimeter.md)
  - [7.2.2 Area](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/7-2-2-area.md)
- 7.3 Position & Direction
  - [7.3.1 Coordinates](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/7-3-1-coordinates.md)
  - [7.3.2 Translation](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/7-3-2-translation.md)

### 8 Year 4 - Statistics
- 8.1 Statistics
  - [8.1.1 Types of Data](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/8-1-1-types-of-data.md)
  - [8.1.2 Pictograms & Bar Charts](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/8-1-2-pictograms-and-bar-charts.md)
  - [8.1.3 Line Graphs](https://senecalearning.com/en-gb/revision-notes/primary/maths/maths-year-3-and-4-national-curriculum/8-1-3-line-graphs.md)