UK Shed Sizes Guide: 6×4 to 12×8 With Real Internal Dimensions

A shed sold as 6×4 will not give you six feet by four feet of usable floor. Shed sizes in the UK are quoted in nominal imperial feet describing the building footprint, and the space you can actually stand in and store things in is smaller once cladding, framing and the door reveal are accounted for. The difference is modest on a small shed and significant across a large one, and it is the single most common reason a shed turns out to be too small for the job it was bought for.

This guide converts the standard nominal sizes into the internal dimensions buyers should plan around, and sets them against the things people actually store. The internal figures given are typical rather than universal: different constructions lose different amounts, and any shed should be checked against the manufacturer specification before ordering. What does not vary is the principle, which is that the nominal size is an outside measurement and your storage is an inside one.

Key findings at a glance

• Nominal shed sizes in feet describe the footprint, not the usable internal floor area.
• Cladding thickness and framing typically remove several centimetres from each internal dimension, and overlap cladding loses more than tongue and groove.
• Eaves height, not ridge height, determines what can stand against the wall, which is where most storage actually goes.
• Door opening width is the constraint that decides whether a mower, bike or wheelbarrow can get in at all.
• Apex roofs add ridge height that is rarely usable for storage but makes the interior feel workable.
• Pent roofs suit sheds placed against a boundary or fence, because the fall can be directed away from the neighbouring side.
• The base, not the shed, determines how long a timber building lasts in a British garden.

Why nominal and internal sizes differ

A shed is described by its footprint because that is what the buyer needs in order to know whether it will fit in the garden. That footprint is measured to the outside of the framing, and in many cases to the outside of the cladding, which on overlap boarding projects beyond the frame. Inside the frame, the wall studs and the cladding both eat into the floor area. The floor deck itself usually sits within the wall line rather than under it.

The result is that internal width and depth commonly run several centimetres short of the nominal conversion on each dimension. On a small shed this is an inconvenience. On a large shed where the buyer has planned a workbench along one wall to an exact length, it is a problem. Always measure the internal dimension against your intended contents, and always allow for the thickness of anything hung on the wall.

Height is where sheds are really lost

Buyers focus on floor area and then discover that the useful constraint is height at the wall. An apex shed quotes a ridge height that applies only along the centre line, where nothing is stored. What matters for shelving, for a wheelbarrow stood on end or for a stack of storage boxes is the eaves height, which is considerably lower.

This also interacts with planning. The Planning Portal sets out the conditions under which outbuildings are permitted development, and those conditions include limits on height, with lower limits applying where the building sits close to a boundary and different limits for dual pitched roofs. Anyone considering a taller building, or one within two metres of a boundary, should check the current conditions before ordering rather than afterwards.

Doors decide what gets stored

The door opening is the most underspecified dimension on a shed listing and the one that most often causes returns. A single door on a small shed can be narrow enough that a standard wheelbarrow will not pass through squarely, and a petrol mower with a fixed handle frequently will not. Double doors solve this but reduce the wall length available for shelving, because neither leaf can be blocked.

Plan the doorway around the largest item first. If a bicycle is going in and out daily, the handlebar width and the turning space inside both matter more than the total floor area. If a ride on mower or a large wheelbarrow is the main occupant, a double door shed of a given size will be more useful than a larger single door one.

Standard sizes and what they hold

The table below converts the standard UK nominal shed sizes into approximate internal dimensions and sets out realistic contents. Internal figures are typical allowances for framing and cladding and should be checked against the specification of the individual model.

What this means for UK homes

Buy one size up from the one that appears to fit your list. Sheds fill, and the shed that exactly accommodates today’s contents has no circulation space, which makes it a stack rather than a store. As a rule of thumb, keep a clear floor strip of at least 60cm from the door to the back wall so you can reach the far end without unloading the near end.

Get the base right before anything else. A level, free draining base of concrete or paving slabs, sized to the shed footprint rather than larger, keeps water away from the bearers and is the main determinant of how long the building lasts. Leave a gap of at least 30cm around the shed for maintenance and airflow, and treat the timber on the schedule the manufacturer specifies rather than when it starts to look tired. Our wooden sheds and garden storage UK and metal sheds and garden storage UK ranges cover the main constructions, while garden cabins and summer houses UK is the right place to look if the building is going to be occupied rather than used for storage. Keep garden seating and tables out of the shed where possible, since our outdoor garden furniture UK range is built to live outside under covers and takes up storage space that tools need. Furniture in Fashion sees the same story often enough to make it a rule: the shed is rarely too big.

Methodology

This 2026 guide was compiled from standard UK shed specification conventions, from the nominal to metric conversions used across the market, and from our editorial assessment as a UK garden building and furniture retailer. Internal dimensions are typical allowances based on common framing and cladding constructions and are presented as approximations to be verified against individual product specifications. The guide does not include measured sampling of manufactured sheds, survey fieldwork or proprietary sales data, and no market statistics are presented. Planning conditions referred to are those published for outbuildings by the Planning Portal and should be checked at the point of purchase.

Citing this report

Websites and publications may cite this 2026 guide with credit to Furniture in Fashion and a link back to us. It is a specification led guide to nominal and internal shed dimensions based on standard construction practice, and the internal figures should be described as typical allowances rather than measured results.

Frequently asked questions

Is a 6×4 shed really six feet by four feet inside?

No. The nominal size describes the footprint measured externally. Once framing and cladding are accounted for, the usable internal floor is typically several centimetres short on each dimension, so plan around roughly 174cm by 113cm rather than the full conversion.

What size shed do I need for a mower and bikes?

An 8×6 is the smallest size that comfortably takes a mower, two bicycles and wall shelving while leaving room to turn around. A 7×5 will hold a mower and one bicycle but leaves little circulation, and a 6×4 is a store rather than a space you work in.

Do I need planning permission for a garden shed?

Most domestic sheds are permitted development, but conditions apply on height, position relative to boundaries, and the proportion of the garden covered. The Planning Portal publishes the conditions for outbuildings, and they are worth checking before ordering, particularly for taller buildings or anything close to a boundary.

Apex or pent roof: which should I choose?

Apex gives more headroom at the centre and a more usable feel inside. Pent is better against a fence or wall, because the fall can be directed away from the boundary, and it suits positions where overall height is restricted.