Child yield and how play space is calculated
Child yield turns a unit mix into a play space requirement. How the calculation works, which inputs move it, and how provision is distributed by age band.
Child yield is the estimated number of children a residential scheme will house, broken down by age group, and it is the number that drives the play space requirement. In London the chain is explicit: estimate the child population from the unit mix and tenure using the Greater London Authority population yield calculator, then provide 10 m² of playable space per child. A scheme of 80 flats with a yield of 36 children needs 360 m² of playable space. Outside London the same logic appears in local open space standards expressed per dwelling or per head, and the arithmetic matters just as much, because the figure sets the land take and the section 106 position.
Get the yield wrong at design stage and the scheme either carries unusable leftover space or arrives at committee short of provision with nowhere to put it.
What child yield estimates
Child yield is a planning estimate, not a census. It takes the number of homes, their size in bedrooms, and their tenure, and applies observed household composition rates to produce an expected number of children in defined age bands.
The age bands matter as much as the total, because each band needs a different kind of space in a different place. Under-fives need doorstep provision within sight of a front door. Five to eleven year olds will travel a few minutes. Older children and teenagers need space further away and will not use a toddler play area whatever the drawing says.
Tenure is the input people forget. Affordable and social rented homes house more children per dwelling than market homes of the same size, so changing the tenure split at a late stage changes the yield and therefore the requirement. A scheme that swaps 20 market flats for 20 affordable rent flats to improve its policy position will usually need more playable space than the original drawing allowed for.
Inputs the calculation uses
Four inputs produce the number.
The unit mix by bedroom count is the primary driver. A three bedroom home houses more children than a one bedroom flat, and the difference between a 60 per cent one and two bedroom mix and a 40 per cent mix is large enough to change the land budget.
Tenure follows, split between market, intermediate and social or affordable rented. Location is the third input, because household composition varies by area, and the calculator is built around borough-level or ward-level rates rather than a single national figure. The fourth is the development's own characteristics where they are relevant, such as a specialist older persons scheme or student accommodation, which should be excluded or treated separately rather than run through a general rate.
Two exclusions are worth stating in the submission. Student accommodation and most older persons housing generate no child yield, and a mixed scheme should set those elements out separately so the officer can see they were considered rather than ignored. Where a scheme includes a small number of family sized units in an otherwise one and two bedroom block, say so, because it changes the age band distribution and the kind of space required.
Converting yield into a play space requirement
Multiply the yield by the standard. In London the standard is 10 m² of playable space per child, applied to the total yield across all age groups.
| Scheme | Estimated yield | Requirement at 10 m2 per child |
|---|---|---|
| 40 one and two bedroom flats | 9 children | 90 m² |
| 80 flats, mixed sizes, 35 per cent affordable | 36 children | 360 m² |
| 120 homes including 30 houses | 95 children | 950 m² |
Those are illustrative figures to show the arithmetic rather than yields for any real scheme. Run the calculator for the actual mix, tenure and location.
The figure is a quantity standard and it is not the whole policy test. A scheme can meet 10 m² per child with a strip of amenity grass behind a bin store and still fail, because the policy also expects the space to be accessible, overlooked, usable and suitable for the age groups it serves. Quantity is the floor, not the ceiling, and the qualitative argument is where most of the officer discussion happens.
Age group provision and doorstep playable space
Provision is distributed, not pooled into one compound. The usual pattern allocates doorstep space for under-fives within or immediately adjacent to the block they serve, a local play area for five to eleven year olds within a short walk, and youth provision for older children at the scheme or neighbourhood scale.
Doorstep playable space is the element that constrains layout. It needs to be within about 100 m of the homes it serves, visible from dwellings, separated from vehicle routes, and designed so that an adult can supervise from a window or a doorway. On a flatted scheme that usually means a courtyard, and it means designing the courtyard for play rather than labelling an existing one.
Teenage provision is the element most often fudged. A multi-use games area is one answer and it brings noise and management issues with it, which is why some schemes make a contribution towards off-site youth provision instead. Both are defensible, and a drawing that marks a bench on a path as youth space is not.
Equipment is optional. Playable space can be landscape, topography, planting, water, logs and informal kickabout grass, and the design guidance encourages exactly that rather than a fenced compound of catalogue equipment. Equipped areas must comply with the play equipment and surfacing standards, so a landscape-led approach often costs less to maintain.
On-site provision against a contribution
Where the scheme cannot deliver the full quantity on site, a financial contribution towards off-site provision secured through a section 106 agreement is the normal route. The order of preference in most policies is on-site first, then improvement of existing off-site provision within walking distance, then a contribution.
Three things make a contribution case stronger. Evidence that on-site delivery was tested and the layout cannot in fact accommodate it. An identified off-site facility within a reasonable walk, with a costed improvement scheme. And an explanation of how the contribution figure was calculated, usually a cost per square metre of provision plus a commuted maintenance sum.
Councils resist contributions for doorstep provision for under-fives, because the whole point of doorstep space is that it is at the door. Expect to be pushed to find that space on site even where a contribution is accepted for older age groups.
Illustrative example. A scheme of 80 flats on a constrained town centre site has a yield of 36 children and a requirement of 360 m². The podium courtyard delivers 180 m² of usable playable space, including 90 m² of doorstep provision overlooked by the flats. The remainder is met by a contribution towards upgrading a park 250 m away, with the figure built from a cost per square metre plus ten years of maintenance. An Open Space Assessment sets out the existing provision and its quality, and the Play Space Assessment sets out the yield, the calculation and the distribution.
Overlap with open space standards
Play space and open space are different requirements that are frequently counted twice. A local plan may require a quantum of public open space per dwelling, a separate quantum of amenity space, private amenity space for each home, and playable space from the child yield. Some of those can overlap and some cannot.
The safe approach is a schedule that lists each requirement, the policy it comes from, the area provided and whether any area is counted against more than one requirement, with a note explaining why the double count is acceptable. An officer who can see the overlap stated openly will engage with it. One who finds the same courtyard counted three times will discount the whole schedule.
Private balconies and gardens rarely count towards playable space. Communal amenity space can count where it is designed for play. Roof terraces sometimes count and sometimes do not, depending on access, supervision and whether children can reach them independently. Check the policy wording rather than assuming.
Presenting the calculation in a schedule
Put the whole chain on one page: unit mix by bedroom and tenure, the yield by age band, the requirement at the applicable standard, the provision by location and type, any overlap, and the residual to be met by contribution.
Number the spaces on the landscape drawing and use the same numbers in the schedule. Officers check these figures by hand and a schedule that cannot be reconciled with the drawing generates a round of questions that costs a fortnight. State which calculator version and which date you ran, because the inputs are periodically updated.
Where the mix changes during determination, rerun the yield rather than adjusting the total by eye. A ten unit change to the affordable element can move the requirement by more than the area of the space you were arguing about. The full set of report types shows which assessments sit alongside the play space work on a residential scheme.
This is general guidance, not legal advice. Standards and population yield rates vary by authority and are updated periodically, so check the current policy and calculator with your local planning authority before relying on these figures.
Frequently asked questions
How is child yield calculated for a planning application?
From the unit mix by bedroom count, the tenure split, and the location, using observed household composition rates. In London the Greater London Authority population yield calculator is the standard tool. The output is a number of children by age band, which is then multiplied by the applicable playable space standard.
How much play space does a scheme have to provide?
In London, 10 m2 of playable space per child across the estimated yield. Outside London the requirement comes from the local plan open space standard, which may be expressed per dwelling or per head of population. Check the adopted policy, since standards and the way they are applied vary by authority.
Does tenure change the child yield?
Yes, substantially. Affordable and social rented homes house more children per dwelling than market homes of the same size. A late change to the tenure split to improve the policy position will usually increase the yield and therefore the playable space requirement, which can be awkward once the layout is fixed.
Can a financial contribution replace on-site play space?
Sometimes, where the layout cannot accommodate the full quantity. Policies normally prefer on-site provision, then improvement of nearby existing provision, then a contribution. Councils resist contributions for doorstep provision for under-fives, because that space has to be at the door to work.
Do balconies and private gardens count towards playable space?
Rarely. Private balconies and gardens are usually counted as private amenity space rather than playable space. Communal space can count where it is designed for play and properly overlooked. Roof terraces depend on access and supervision, so check the policy wording instead of assuming the area counts.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.