Choosing the wrong shed size is one of the most common and costly mistakes backyard builders make. Build too small and you’ll be cramming bikes against the lawnmower within a season. Build too big and you’ve spent thousands more than you needed to — and possibly triggered a council permit process you weren’t expecting. This guide walks you through every common shed size, what each one fits, what it costs in Australian materials, and exactly how to calculate the right size for your property and your needs.
Common Shed Sizes at a Glance
Australian sheds are typically described in feet (a legacy of imperial measurements still used in building plans), but materials are sold in metric. The table below covers the five most common sizes, from a compact garden store to a full double-garage workshop.
| Size (ft) | Approx Area (sq ft / m²) | Good For | Approx Material Cost (AU$) |
|---|---|---|---|
| 6×8 | 48 sq ft / 4.5 m² | Garden tools, mower, small storage | $800 – $1,400 |
| 8×10 | 80 sq ft / 7.4 m² | Tools, bikes, garden equipment, potting bench | $1,500 – $2,500 |
| 10×12 | 120 sq ft / 11.1 m² | Full tool storage, ride-on mower, small workshop bench | $2,500 – $4,000 |
| 12×16 | 192 sq ft / 17.8 m² | Workshop + storage, two bikes + tools + mower | $4,500 – $7,500 |
| 16×20 | 320 sq ft / 29.7 m² | Full workshop, vehicle storage, large machinery | $8,000 – $14,000+ |
Material costs above are for framing timber, roofing, cladding, fasteners, and a basic skid foundation. They do not include a concrete slab, electrical wiring, or premium fittings. Actual costs vary by region — timber and Colorbond prices in regional WA or NT will differ from metro Sydney or Melbourne.
How to Calculate the Right Shed Size
Guessing is how people end up with a shed that’s already full before they’ve finished building it. Follow these steps instead.
Step 1: List Everything You Plan to Store
Write down every item you want inside the shed. Don’t forget seasonal gear — Christmas decorations, camping equipment, folding chairs. Group items into categories: large equipment (ride-on mower, trailer), medium tools (wheelbarrow, ladders), small tools (handtools, garden chemicals), and bench/workspace if needed.
Step 2: Measure Your Largest Items
The floor plan is dictated by your biggest pieces. A standard ride-on mower is roughly 1.5m wide × 1.8m long. A full-size bicycle is about 0.6m × 1.8m. If you need to manoeuvre these inside, add clearance — typically 600mm on at least one side.
Step 3: Sketch a Basic Floor Plan
Draw your shed footprint to scale (1cm = 50cm works well on A4 paper). Arrange your large items first, then add shelf runs along walls for smaller gear. Leave at least 900mm of clear walkway through the centre.
Step 4: Add the 20% Buffer
Once you’ve filled your floor plan with current items, multiply the total floor area by 1.2. This accounts for the fact that storage always expands to fill available space. If your items need 8m², plan for a shed with at least 9.6m² of usable floor area.
Step 5: Check Your Site Constraints
Boundary setbacks, easements, tree root zones, and council overlays all limit where and how big you can build. Most Australian councils require a minimum 900mm setback from side and rear boundaries for a Class 10a shed, though this varies. Check with your local council before finalising dimensions.
Australian Building Permit Thresholds
Permit requirements for sheds vary across every state and territory in Australia. As a general guide, most councils allow structures up to 10m² without a building permit, provided the structure meets certain height, setback, and cladding conditions. This means a 6×8 shed (4.5m²) is typically permit-free, and an 8×10 shed (7.4m²) often qualifies too — but a 10×12 (11.1m²) usually crosses the threshold.
Always check with your local council before you build. Rules differ not just between states but between council areas within the same state. In Queensland, the exempt threshold is set by the Queensland Development Code. In NSW, it falls under the State Environmental Planning Policy (SEPP). Victoria uses the Planning and Environment Act. The penalty for building without a required permit can include demolition orders.
Floor Plan Layouts by Size
6×8 Shed (4.5 m²)
With this footprint, simplicity is key. Run shelving along both long walls (900mm deep maximum, or you lose the walkway). A pegboard panel on one short wall handles hand tools. The remaining floor space fits a lawnmower or a few large bins. No room for a workbench unless you fold it against the wall.
8×10 Shed (7.4 m²)
Two layouts work well: open-plan storage (shelves all around, clear centre), or one wall dedicated to a narrow workbench. A standard push mower and two bikes can coexist here if bikes are hung on the wall or ceiling hooks. Doubles as a potting shed if you add a window in the framing.
10×12 Shed (11.1 m²)
The sweet spot for most Australian backyards. One layout: workbench along the back wall with shelving above, lawnmower bay on the right, bikes or bins on the left. Another layout: split the shed in half — storage at the rear, open workshop area at the front with natural light from a double door.
12×16 Shed (17.8 m²)
Large enough for a genuine workshop zone. Common layout: ride-on mower bay on one side (about 2m × 2.5m), workbench and tool storage along the back wall, shelving zone on the remaining side wall. If you add a loft (which is very achievable at this size), you essentially double your storage without adding to the footprint.
16×20 Shed (29.7 m²)
This is a serious structure. Think of it as a single-car garage plus a workshop. At this size, you’d typically partition the space — a double-door vehicle or machinery bay at one end, a fully equipped workshop at the other. Electrical wiring is almost always worth adding. Building permits are required in every Australian state at this size.
Which Size Should You Choose?
For most Australian homeowners doing general garden and tool storage, the 10×12 hits the ideal balance of capacity, cost, and build effort. If you want a genuine workshop space or need to house a ride-on mower plus tools, step up to 12×16. If all you’re storing is a push mower and some rakes, an 8×10 is practical and usually permit-free.
The mistake nearly everyone makes is going one size smaller than they need. The extra 2 feet in each direction costs very little in incremental materials but adds enormous usable space. If you’re choosing between 8×10 and 10×12, go 10×12.
Get Your Plans Before You Buy Materials
Knowing your size is only the first step. You still need accurate cut lists, framing plans, roof details, and foundation specs to build confidently. Buying materials without a plan leads to waste, trips back to the hardware store, and structural errors that are expensive to fix later.
Ted’s Woodworking includes over 16,000 detailed plans across every shed size covered in this guide — all with complete cut lists, step-by-step instructions, and materials lists sized for standard Australian timber dimensions. It’s the reference library every backyard builder needs before they pick up a saw.
Browse shed plans and get your complete build package at Ted’s Woodworking →
