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Shed Size Calculator
Use this free shed size calculator to find the right shed size before you buy or build one. List the mower, bikes, tools, and boxes you plan to store, choose how much walking space you want, and it gives you the floor area you need, the smallest shed that fits, and a rough cost by material.
What will you store? Set the quantity of each item.
Floor areas are the space each item occupies on the floor, including room to open doors and lids. Wall shelves do not count — only floor space does.
| Amount | Value |
|---|---|
| Items floor area | 48 sq ft |
| Walking space (25%) | 12 sq ft |
| Total floor area needed | 60 sq ft |
| Recommended shed | 8 × 8 ft (64 sq ft) |
| Spare space in that shed | 4 sq ft |
| Cost hint (wood, $50/sq ft) | $3,200 |
How it works
A shed that is too small is worse than no shed at all: you end up stacking things in front of each other, and the item at the back is the one you always need. A shed that is too big wastes money and yard space. This calculator sizes a shed from the things going into it, instead of guessing from the size of the yard.
Each item takes a floor area, including the room to use it. A push mower takes about 8 square feet, a riding mower about 20, a bicycle about 6, a tool bench about 12, a shelving unit about 6, and a storage box about 4. The calculator multiplies each item by its quantity and adds them up. One push mower, two bikes, one tool bench, and four boxes come to 8 + 12 + 12 + 16 = 48 square feet of floor space.
Needed area = item area × (1 + walking space)
Recommended shed = smallest standard size with area ≥ needed area
Cost hint = recommended shed area × cost per square foot
Walking space is the part people forget. A shed packed wall to wall with stuff is unusable, because you cannot reach anything without moving three other things first. The calculator adds 15 percent for a tight fit, 25 percent for comfortable access, or 40 percent if you want to work inside the shed at a bench. At 25 percent, 48 square feet of items needs 48 × 1.25 = 60 square feet in total.
Sheds are sold in standard sizes, so the calculator rounds up to the smallest standard shed that fits: 6 × 8 (48 sq ft), 8 × 8 (64 sq ft), 8 × 10 (80 sq ft), 10 × 10 (100 sq ft), 10 × 12 (120 sq ft), and 12 × 16 (192 sq ft). A 60-square-foot need fits an 8 × 8 shed with 4 square feet to spare. Buying the next size up is usually wise if you plan to add anything in the next few years — sheds rarely get emptier.
The cost hint multiplies the recommended shed area by a rough cost per square foot for the material: about $50 for wood, $35 for metal, and $40 for resin. An 8 × 8 wood shed works out to about $3,200. That is a planning figure only — real prices vary with the brand, the foundation, delivery, and whether you build it yourself. Check local rules too: many areas need a permit or a setback from the property line for sheds over a certain size, often 100 or 120 square feet.
Worked example
You want a shed for 1 push mower, 2 bicycles, 1 tool bench, and 4 storage boxes, with comfortable walking space, in wood.
Step 1: Add the item areas — mower 1 × 8 = 8, bikes 2 × 6 = 12, bench 1 × 12 = 12, boxes 4 × 4 = 16, for a total of 48 square feet.
Step 2: Add walking space — 48 × 1.25 = 60 square feet needed.
Step 3: Pick the smallest standard shed that fits — 6 × 8 is only 48 square feet, so the next size, 8 × 8 at 64 square feet, is the pick, with 4 square feet to spare.
Step 4: Cost hint — 64 × $50 = $3,200 for wood.
The result is an 8 × 8 ft shed (64 sq ft) for a 60 sq ft need, with a wood cost hint of about $3,200. That is exactly what the calculator shows for these inputs.
FAQ
What size shed do I need for a lawn mower and bikes?
Add up the floor areas: a push mower takes about 8 square feet, each bike about 6, and a tool bench about 12. One mower, two bikes, and a bench come to 32 square feet of items, or 40 square feet with comfortable walking space — an 8 × 8 shed. A riding mower needs 20 square feet on its own, so add that first before sizing.
How much walking space should I allow in a shed?
Allow 25 percent extra for comfortable access, which is the default here. Use 15 percent if the shed is only for storage and you will reach in from the door, and 40 percent if you plan to work at a bench inside. Without walking space, the items at the back become unreachable.
Is an 8 × 8 shed big enough?
An 8 × 8 shed holds 64 square feet, which fits a push mower, two bikes, a bench, and several boxes with room to walk — the worked example above. It is too small for a riding mower plus a full workshop, or for a family with four or more bikes. If you are close to the limit, go up to 8 × 10 instead of squeezing in.
How much does a shed cost?
As a rough guide, wood sheds run about $50 per square foot, metal about $35, and resin about $40, so an 8 × 8 wood shed is about $3,200. The real price depends on the brand, the foundation, delivery, and assembly. Get a quote for the exact size and material before budgeting, and check whether a permit is needed.
Do I need a permit for a shed?
It depends on where you live. Many areas allow small sheds under 100 or 120 square feet without a permit, but still require a setback from the property line and a limit on height. Larger sheds often need a permit and a foundation. Check with your local building department before you buy, because moving a built shed is expensive.