Garden Shed Size Calculator
Choosing the right shed size means balancing what you need to store — mowers, bikes, tools, or a full workshop setup — against your garden space and UK permitted development limits, which generally cap outbuildings at 2.5m in height near boundaries without planning permission. Get the size wrong and you either waste garden space or end up with a shed you can't move around in. Tell us what you're storing below and we'll suggest a floor area and matching standard shed sizes, plus a few well-reviewed sheds to get you started, keeping in mind most builds still need a solid, level base.
What do you need to store?
Tick everything that applies — we'll estimate the floor area you need.
Select at least one item above to see your recommended shed size.
Recommended sheds
A few well-reviewed options to match the size you've calculated.
Currently unavailable
Pros
- Traditional overlap timber cladding
- Budget-friendly for the size
- Includes windows for natural light
Cons
- Requires annual timber treatment
- Wood
- Small gardens
- 8x6ft
£449.99
Pros
- 8mm overlap cladding handcrafted from sustainable timber
- Felt and fixings included
- Windows for natural light
Cons
- Requires annual timber treatment
- Base not included
- Resin
- Small gardens
- 145x82x125cm
Currently unavailable
Pros
- Weatherproof resin construction, no rot or rust
- Lockable doors and piston-assisted lid
- Compact footprint good for patios and small gardens
Cons
- Smaller capacity than a full-size shed
Frequently asked questions
Do I need planning permission for a shed this size?
In most UK gardens, sheds fall under permitted development and don’t need planning permission provided they cover no more than 50% of the garden, sit behind the front of the house, and are no taller than 2.5m within 2m of a boundary (up to 4m dual-pitch roof elsewhere). Larger workshop-sized buildings or sheds near a boundary may still need a check with your local council.
What base do I need for my shed?
Small sheds (up to around 6x4ft) are usually fine on paving slabs or a timber frame base. Anything from 8x6ft upwards, or sheds housing heavier items like a workshop, benefits from a proper concrete or concrete-and-slab base to keep the floor level and prevent damp and movement over time.
How much extra space should I allow beyond my stored items?
We add a 30% buffer on top of the raw footprint of your items to account for walking space, opening doors, and reaching things at the back — sheds packed edge-to-edge with no access space are much harder to actually use.
Is it better to size up if I am unsure?
Generally yes. Sheds are cheap relative to the cost of running out of space later, and buying one size up gives you room for future purchases like a second bike or a mower upgrade without needing a new shed in a couple of years.
How this calculator works
The calculator starts from a simple premise: every item you store takes up floor space. Instead of guessing, we assign each common shed item a realistic footprint in square metres — a lawn mower takes about 1 m², a pair of bicycles about 1 m², a stack of garden tools around 2 m², and folded garden furniture around 2.5 m². When you tick the items you plan to keep in your shed, we sum their individual footprints to get your “raw storage footprint.”
To that figure we add a 30% buffer for walking space, opening doors, and reaching things at the back. This is an industry rule-of-thumb for garden buildings — a shed packed edge-to-edge with boxes and tools is much harder to actually use than one that leaves a little moving room. The recommended floor area is therefore raw footprint × 1.3.
Finally, the calculator compares your recommended area against a table of standard UK shed sizes — from 6×4 ft (2.2 m²) up to 14×10 ft (12.6 m²) — and suggests the three smallest sizes that are at least as large as your recommended area. If your needs exceed the largest standard size, the calculator advises looking at a bespoke garden room rather than an off-the-shelf shed.
Typical UK shed sizes and what they fit
These are internal floor areas — the actual usable space is slightly less after you account for wall thickness and any shelving that juts into the room. Sheds with pent roofs also lose headroom on the low side, which may limit storage of tall items like rakes and ladders against that wall.
| Shed size | Floor area | Good for |
|---|---|---|
| 6×4 ft | 2.2 m² | Mower + hand tools + small pots |
| 7×5 ft | 3.2 m² | Mower + hand tools + folded chair + small bike |
| 8×6 ft | 4.3 m² | Mower + 2 bikes + tools + some garden furniture |
| 10×6 ft | 5.4 m² | Mower + 2 bikes + tools + furniture + compost bags |
| 10×8 ft | 7.2 m² | Full combo: mower + bikes + tools + furniture + storage |
| 12×8 ft | 8.6 m² | Workshop setup with bench + storage + garden gear |
| 12×10 ft | 10.8 m² | Large workshop, power tools, substantial storage |
| 14×10 ft | 12.6 m² | Bespoke workshop or garden room equivalent |
UK planning permission for sheds
Most garden sheds in the UK fall under permitted development and do not require planning permission, provided they meet the following conditions: the shed covers no more than 50% of the total garden area; it sits behind the front elevation of the house; it is single-storey with a maximum eaves height of 2.5m and an overall height of 4m for a dual-pitch roof (2.5m within 2m of a boundary); and it is not used as self-contained living accommodation.
If you live in a listed building, a conservation area, an Area of Outstanding Natural Beauty (AONB) or a National Park, the rules are tighter. The same applies if your property already has other outbuildings, sheds or extensions that bring you close to the 50% coverage limit. In these cases, it is always worth checking with your local planning authority before buying a shed or laying a base.
Building Regulations approval is generally not needed for a shed under 15 m² internal floor area that is at least 1m from any boundary, or under 30 m² if it is constructed of non-combustible materials or sits at least 1m from the boundary. However, any structural changes — like adding windows with opening lights, installing a fixed heater, or converting part of the shed into a home office with insulation — may trigger a Building Regulations assessment.
Worked example: What size shed for a mower, two bikes and tools?
Suppose you need to store a lawn mower (1 m²), two bicycles (1 m²) and a set of garden tools (2 m²). The raw storage footprint is 1 + 1 + 2 = 4 m². Adding the 30% access buffer gives 4 × 1.3 = 5.2 m² recommended floor area.
Looking at the standard sizes table, the smallest shed that meets or exceeds 5.2 m² is the 10×6 ft (5.4 m²), followed by the 10×8 ft (7.2 m²) if you want a little extra room. An 8×6 ft (4.3 m²) would be too tight — you would struggle to walk between the bikes and the tool storage. This is a common mistake: the raw items fit on paper, but the shed feels unusable once you try to move around inside.
Common mistakes when choosing a shed size
- Buying the same size as your current shed without measuring what you actually store now — clutter tends to grow, and a replacement shed that matches the old one leaves no room for expansion.
- Forgetting about door swing and shelving overhang. A shed door that opens inward needs floor space behind it clear of storage. Wall-mounted shelving also reduces the usable floor area by the depth of the shelves (typically 30–45 cm).
- Not accounting for the base. A concrete base extends slightly beyond the shed footprint, and the shed itself is measured externally by manufacturers — internal space is 10–15 cm smaller in each dimension because of the wall frame and cladding.
- Assuming you can store everything against the walls. Tall items like rakes, strimmers and ladders need to lean or be hung, which requires wall height and at least some clear wall space — not every wall can be lined shoulder-to-shoulder with shelves.
- Choosing by price per square foot rather than what fits. A 6×4 ft shed might cost less than half of an 8×6 ft model, but if you need to store a bike and a mower you will outgrow it within a season and end up buying twice.
- Placing the shed in the darkest, dampest corner of the garden without considering access for wheelbarrows, lawn mowers or a future replacement. A shed that is hard to reach is a shed you use less.
What to look for when buying a shed
Once you have settled on the right size, the next decision is construction. Pressure-treated timber sheds offer the best longevity in the UK’s damp climate — look for 12 mm or thicker cladding and a tongue-and-groove construction, which holds up better than overlap (feather-edge) boards over time. A mineral-felt roof and a treated timber base are standard on most mid-range models, but check whether felt and guttering are included or sold separately.
Pent sheds (sloping roof, taller at the front) are the most versatile for positioning against a wall or fence, while apex sheds (triangular roof) offer more headroom for shelving along the sides. If headroom matters for a workshop setup, a 1.8 m or 2 m eaves height makes a noticeable difference over the standard 1.5 m eaves found on compact models.
Finally, consider the door. A double-door or wide single-door shed (typically 0.9 m wide) makes it much easier to wheel a mower or bring in large items than the narrow 0.6 m door found on entry-level 6×4 ft sheds. If you plan to take a ride-on mower or bulky furniture in and out, check the internal door width against your largest item before buying.
More questions answered
Do I need planning permission for a shed this size?
In most UK gardens, sheds fall under permitted development and don’t need planning permission provided they cover no more than 50% of the garden, sit behind the front of the house, and are no taller than 2.5m within 2m of a boundary (up to 4m dual-pitch roof elsewhere). Larger workshop-sized buildings or sheds near a boundary may still need a check with your local council.
What base do I need for my shed?
Small sheds (up to around 6×4ft) are usually fine on paving slabs or a timber frame base. Anything from 8×6ft upwards, or sheds housing heavier items like a workshop, benefits from a proper concrete or concrete-and-slab base to keep the floor level and prevent damp and movement over time.
How much extra space should I allow beyond my stored items?
We add a 30% buffer on top of the raw footprint of your items to account for walking space, opening doors, and reaching things at the back — sheds packed edge-to-edge with no access space are much harder to actually use.
Is it better to size up if I am unsure?
Generally yes. Sheds are cheap relative to the cost of running out of space later, and buying one size up gives you room for future purchases like a second bike or a mower upgrade without needing a new shed in a couple of years.
Can I put a shed on uneven ground?
A shed needs a level, firm base to prevent the frame from twisting and the door from jamming. Small sheds can sit on paving slabs bedded on sharp sand, but larger sheds and workshops should have a concrete base (minimum 75–100 mm thick) or a properly built timber sub-frame on concrete piers.
Should I insulate my shed?
If you plan to use the shed as a workshop, home office, or for storing temperature-sensitive items, insulation is worth the investment. Uninsulated timber sheds can drop below 5°C in a UK winter, which can damage paints, adhesives and electronics stored inside.
How long should a timber shed last?
A well-maintained pressure-treated timber shed typically lasts 10–15 years. Annual treatment with a wood preservative, keeping the base clear of vegetation, and repairing damaged felt roofing promptly will all extend its life. An untreated shed may start to rot within 3–5 years in a damp UK climate.
What is the difference between overlap and tongue-and-groove cladding?
Overlap (feather-edge) cladding uses horizontal boards that overlap each other. It is cheaper but can warp, shrink and let in draughts over time. Tongue-and-groove cladding has interlocking edges that create a tighter, more stable wall — it costs more but offers better weather resistance and a longer life, which is worth the extra for a larger or long-term shed.