About ShedSize
Why shed sizes disappoint
Almost everyone who buys a shed discovers within a year that it is too small, and the reason is simple: people measure the floor area of the items they own, but forget the space needed to reach them. A mower parked against the back wall is useless if a stack of boxes blocks the door, and a bike hung in a corner still needs clearance to lift it down. Sheds are also bought for today's belongings, not next year's, and gardens accumulate tools, pots, sports gear and children's equipment steadily. This calculator adds up item footprints, adds thirty percent walkway space, and matches the total to a standard shed size, so the shed you buy fits the garden you actually have.
How the calculation works
Each item type is given a realistic footprint: a bike needs about 0.9 square metres including handlebar clearance, a push mower about 1.2, a ride-on mower about 2.0, and a standard storage box about 0.4. Shelving is counted at its actual footprint, since shelves use vertical space efficiently but still occupy floor. The sum is the storage footprint, and multiplying by 1.3 adds walkway space for access, which is the single most commonly forgotten factor. The recommended size is the smallest standard shed whose floor area covers the total, with a note when the total exceeds even an extra-large shed, in which case two smaller sheds or a different storage plan may serve better.
Measuring what you actually own
Walk around the garden and garage with a tape measure and list everything the shed must hold, including items currently stored elsewhere that you intend to move in. Measure awkward items such as ladders, wheelbarrows and long-handled tools by their stored footprint, not their length alone, since a ladder stored flat uses far more floor than one hung on a wall. Count bikes honestly, including children's bikes that are outgrown but kept, and allow for seasonal items such as garden furniture cushions and Christmas decorations. It is better to include a doubtful item now than to discover after installation that it lives outside in the rain.
Layout: the difference between fitting and working
A shed that technically fits everything can still be miserable to use if the layout is wrong. Put the most-used items nearest the door, heavy items at ground level, and rarely used items at the back or high up. Wall hooks and hanging rails free surprising amounts of floor: bikes hung vertically, tools on a pegboard, and hoses on a reel can cut the needed footprint by a quarter. Leave a clear path at least sixty centimetres wide from the door to the back, and avoid stacking boxes more than three high, since toppling stacks damage contents and block access. Sketch the layout on paper before ordering, using the footprint figures as a guide.
Base, access and position
A shed needs a level, well-drained base, typically a concrete slab, paving slabs, or a timber frame on compacted hardcore, extending slightly beyond the shed footprint. Position the shed where delivery and assembly are possible, with door access that does not force you through a narrow gate with long panels. Keep the shed a little away from fences and hedges so air circulates and the cladding dries, which greatly extends its life. Check local rules on height and distance from boundaries before ordering, since some areas require planning permission for large or tall outbuildings. A well-positioned shed is used daily; a badly positioned one becomes a dumping ground.
Materials: wood, metal or plastic
Wooden sheds look best in gardens, insulate naturally, and are easy to customise with shelves and hooks, but they need regular treatment and can rot if the base stays damp. Metal sheds are secure, fire-resistant and low maintenance, but they condense moisture inside unless ventilated, and they dent. Plastic sheds are light, weatherproof and easy to clean, but they can flex in wind and are harder to modify with heavy shelving. Whichever material you choose, ventilation matters: a shed that traps damp air will rust tools and grow mould on stored items, so look for vents and a roof overhang that sheds rain away from the walls.
Security and weatherproofing
Sheds are a common target for theft, so fit a hasp and padlock rated for outdoor use, hinge bolts, and a windowless design or obscured windows where possible. Anchor valuable items with a ground anchor and chain, and keep the shed locked even during the day, since opportunistic theft is the most common kind. Weatherproofing starts with the roof: felt needs replacing every few years, while shingle or metal roofs last longer. Seal gaps around the door, keep gutters clear if fitted, and check the base drainage each autumn, since standing water is the fastest route to a rotten floor.
When one shed is not enough
If the calculator recommends an extra-large shed or beyond, consider whether everything truly belongs in one building. Separating garden tools from bikes, sports gear or a workshop often works better than a single cavernous shed, because each building can be positioned and fitted for its purpose. A small bike store by the gate, for example, is far more convenient than a bike buried at the back of a large shed. Alternatively, a lean-to for firewood or bins can free a surprising amount of interior space. The goal is a storage system that gets used, not a single impressive building that is hard to navigate.
Budgeting and future-proofing
Price sheds by floor area and material, but include the base, delivery, assembly and treatment in the total, since those extras can add thirty percent to the headline price. Buy one size larger than the calculator recommends if the budget allows and the garden has space, because gardens accumulate belongings and a slightly larger shed costs far less now than replacing a small one later. Keep the receipt and guarantee, treat wooden sheds annually, and review the contents each spring, removing broken items and anything that has not been used in two years. A shed that is reviewed yearly stays useful for decades.
Shed doors, roofs and ventilation details
Door width decides whether the shed is actually usable: a single narrow door forces awkward manoeuvres with mowers and bikes, while double doors or a wide single door of at least ninety centimetres makes loading easy. Check the door swing and the space in front of the shed, since a door that opens onto a path or fence is a daily frustration. Roof style matters too: a pent roof sheds water to one side and suits placement against a fence, while an apex roof gives headroom for tall shelving and a more traditional look. Ventilation is the detail most buyers overlook: without vents, a sealed shed traps humid air, rusts tools, and grows mould on stored fabric and cardboard. Look for eaves vents or a louvred vent, and leave a small gap under the door where practical. A shed with good doors, a sound roof and real ventilation lasts years longer and protects everything inside, which is the whole point of buying one.