Plymouth Families in Numbers: Children and Households in Census 2021
Plymouth’s Census 2021 figures explained, from 43,364 residents aged under 15 to the household categories recording dependent children.
Published
Census 2021 offers two useful ways to understand Plymouth’s families: the ages of residents and the composition of households. Our analysis counts 43,364 residents aged under 15 and 30,085 households across four categories explicitly recording dependent children. These figures describe Plymouth unitary authority, code E06000026, on 21 March 2021. Each measures something different.[1][2][3][4]
Children Under 15 Made Up 16.38% of Plymouth’s Residents
The official age table, TS007A, groups usual residents into five-year bands. Plymouth’s total was 264,695 people. Adding the three youngest bands gives 43,364 residents aged 0 to 14, equivalent to 16.38% of that same table’s population total.[1][3]
| Age on 21 March 2021 | Plymouth usual residents |
|---|---|
| 4 years and under | 13,205 |
| 5 to 9 years | 15,124 |
| 10 to 14 years | 15,035 |
| Under 15 subtotal, calculated from the three bands above | 43,364 |
The two bands covering ages 5 to 14 were similar in size, with 15,124 residents aged 5 to 9 and 15,035 aged 10 to 14. The youngest band was smaller at 13,205. These are age groups on one census date, so the differences alone cannot establish whether Plymouth’s child population was growing or shrinking.[3]
There’s a boundary to this count: under 15 is narrower than under 18. The next band contains 15,919 people aged 15 to 19, combining older children and adults. Adding that whole band would produce an under-20 count. This table cannot isolate Plymouth’s 15-, 16- and 17-year-olds.[1][3]
Which Households Recorded Dependent Children?
The Office for National Statistics, which produces census statistics, classifies household composition through the relationships between household members. Its TS003 table records 114,560 households in Plymouth. Our analysis adds the four mutually exclusive categories explicitly labelled as having dependent children, giving 30,085 households, or 26.26% of all households.[2][4]
| Household category with dependent children | Plymouth households on 21 March 2021 |
|---|---|
| Single family: married or civil partnership couple | 13,830 |
| Single family: cohabiting couple | 6,043 |
| Single family: lone parent | 8,153 |
| Other household types with dependent children | 2,059 |
| Combined subtotal, calculated from the four categories above | 30,085 |
Married or civil partnership couple households were the largest of these four categories. Lone-parent households with dependent children numbered 8,153, compared with 6,043 cohabiting couple households with dependent children. The additional 2,059 households in the “other household types” category belong in the calculation too. Counting only the three single-family categories would leave them out.[4]
Read “single family” carefully here. The table uses that description for married couples, cohabiting couples and lone-parent families. A single-family household and a lone-parent household are different categories. The table also separately records families whose children are all non-dependent, so a dependent-child total answers a narrower question than a count of every household containing a parent and their children.[4]
Why the Two Percentages Have Different Denominators
The 16.38% age figure means that around 16 in every 100 Plymouth usual residents were under 15. The 26.26% household figure means that around 26 in every 100 Plymouth households fell into the four selected dependent-child categories. A household with several dependent children still contributes one household to the second measure.[2][3][4]
Neither percentage tells you what proportion of Plymouth’s children lived in each family arrangement. That would require counts of children within those arrangements. Dividing the under-15 population by the dependent-child household total would also mix two different classifications, rather than establish an average number of children per family.[1][2][3][4]
How We Calculated the Plymouth Figures
Our analysis uses Census 2021 TS007A and TS003 records retrieved on 20 October 2026, with TS003 definitions from version 4. We select geography E06000026, Plymouth, the 2021 observation and measure 20100, labelled “Value”. The returned geography classification is “2022 local authorities: districts”. Every figure here covers the unitary authority as a whole.[1][2][3][4]
For age, we add TS007A category codes 1, 2 and 3: 13,205 + 15,124 + 15,035. We divide the result by the table’s total of 264,695 and multiply by 100. For households, we add TS003 category codes 5, 8, 10 and 13: 13,830 + 6,043 + 8,153 + 2,059. We divide by 114,560 and multiply by 100. Percentages are rounded to two decimal places.[3][4]
What This Historical Snapshot Leaves Open
Census disclosure controls make small changes to some counts to protect individuals, which can create differences between tables. The Office for National Statistics also flags quality considerations for household and family composition, including changes to “other household types” since 2011. Comparisons with an earlier census need those qualifications.[1][2]
These observations describe 21 March 2021. They leave open how Plymouth’s families have changed since then, and citywide totals cannot show differences between neighbourhoods. When comparing another Plymouth family statistic with these figures, check its geography, observation date and whether it counts people or households.[1][2][3][4]
Sources and checks
These sources were used for this article. Availability, prices and service details can change after the stated check date.
- TS007A - Age by five-year age bands - Nomis - Official Census and Labour Market Statistics
Checked 20 October 2026.
TS007A measures usual residents in five-year age bands. The age observations relate to Census Day, 21 March 2021. The under-15 analysis combines three age bands rather than measuring all under-18s.
- Household composition
- Office for National Statistics
Checked 20 October 2026.
TS003 classifies households by relationships between members. Household observations relate to 21 March 2021. Household counts use a different unit from the usual-resident age counts. ONS flags household and family composition quality considerations and changes to other household types since 2011.
- TS007A
Checked 20 October 2026.
The retained Plymouth E06000026 TS007A total is 264,695 usual residents. The retained age-band counts are 13,205 aged 4 and under, 15,124 aged 5 to 9, 15,035 aged 10 to 14 and 15,919 aged 15 to 19. Our analysis sums age category codes 1, 2 and 3 to 43,364 and divides by 264,695 to obtain 16.38%, rounded to two decimal places. The retained records label the geography as 2022 local authorities: districts and the selected measure as 20100, Value. These citywide age records cannot isolate ages 15 to 17 or establish population change.
- TS003
Checked 20 October 2026.
The retained Plymouth E06000026 TS003 denominator is 114,560 households. The four explicitly dependent-child categories contain 13,830 married or civil partnership couple households, 6,043 cohabiting couple households, 8,153 lone-parent households and 2,059 other households. Our analysis sums household category codes 5, 8, 10 and 13 to 30,085 and divides by 114,560 to obtain 26.26%, rounded to two decimal places. Single-family categories include couple and lone-parent families, while households whose children are all non-dependent are separately classified. The retained records provide household counts rather than counts of children within each household arrangement.