A 120 sq ft prefab kit shed on a gravel pad runs $2,040–$4,080 in DIY materials on this calculator, or $2,760–$5,640 professionally assembled. The same footprint stick-built on a concrete slab runs $1,920–$3,600 in materials but $4,200–$7,560 installed — kit sheds trade a higher material cost for dramatically lower labor, while stick-built flips that trade in the opposite direction.
How this calculator prices a shed
Four lines make up the total, and they move in opposite directions depending on build type: shed material, shed labor, foundation material, and foundation labor. Build type governs the first pair; foundation choice governs the second.
| Build / foundation | Shed material | Shed labor | Foundation material | Foundation labor | Pro total |
|---|---|---|---|---|---|
| Kit, gravel pad | $1,800–$3,600 | $600–$1,200 | $240–$480 | $120–$360 | $2,760–$5,640 |
| Kit, concrete slab | $1,800–$3,600 | $600–$1,200 | $720–$1,200 | $480–$960 | $3,600–$6,960 |
| Stick-built, gravel pad | $1,200–$2,400 | $1,800–$3,000 | $240–$480 | $120–$360 | $3,360–$6,240 |
| Stick-built, concrete slab | $1,200–$2,400 | $1,800–$3,000 | $720–$1,200 | $480–$960 | $4,200–$7,560 |
Computed from this calculator's own per-sq-ft rates. Kit material outprices stick-built material because the prefab panels are the product; stick-built labor outprices kit labor because a crew is framing from raw lumber on site.
Read across the table and the crossover is the whole story: kit sheds cost more to buy and less to build, stick-built sheds cost less to buy and more to build. At 120 sq ft the two land close to the same pro total on a gravel pad — $2,760–$5,640 kit versus $3,360–$6,240 stick-built — which means the deciding factor for most buyers isn't total cost, it's whether they want a weekend assembly project or a from-scratch build with more design flexibility.
Why the foundation line moves more than the shed itself
A concrete slab costs $6–$10 per sq ft in material against $2–$4 for a gravel pad — roughly triple — and its labor rate is also triple: $4–$8 per sq ft against $1–$3. On a 120 sq ft shed that's the difference between a $360–$840 foundation and a $1,200–$2,160 one, a swing of roughly $840–$1,320 driven entirely by what the shed sits on, before a single wall panel is priced.
A gravel pad is the calculator's cheaper default for a reason: for a shed that isn't heated or plumbed, a compacted gravel pad handles drainage and load-bearing without the cure time, forms, and finishing labor a slab requires. Concrete earns its cost when the shed will carry heavy equipment, a workshop floor that needs to stay flat and dry, or a foundation permit that specifically calls for it.
Reading the DIY-vs-pro verdict
The verdict starts "diy-friendly," moves to "conditional" the moment either the build is stick-built or the foundation is a concrete slab, and moves to "pro-recommended" specifically when the build is stick-built and the footprint exceeds 150 sq ft. A kit shed on a gravel pad never leaves "diy-friendly" in this model, regardless of size — the calculator treats pre-engineered panels as removing most of the skill risk that framing from scratch carries.
That distinction matters for anyone shopping by size alone. A 200 sq ft kit shed and a 150 sq ft stick-built shed land in different verdict tiers even though the kit is larger — because the calculator is pricing construction method, not floor area, as the harder problem to get wrong.
Who prices the labor line
Both kit assembly and stick-built shed framing are carpentry work. The Bureau of Labor Statistics puts national carpenters (SOC 47-2031) at a mean $31.55 per hour and $65,630 per year in its May 2025 estimates. The gap between the calculator's kit labor rate ($5–$10/sq ft) and stick-built labor rate ($15–$25/sq ft) isn't a different trade or a different wage — it's the same carpenter spending roughly three times as many hours per square foot when there's no prefab panel doing the work for them.
Siting the shed before you price it
Where a shed goes changes what it costs more than what it is made of, and the siting questions are the ones most often answered after the materials are ordered.
Start with the ground. A shed on soft or sloping ground needs a prepared base, and base preparation is the line that most often turns a weekend project into a contracted one. A level, well-drained spot costs nothing extra; a sloping one costs excavation, fill or a raised platform.
Then check the boundary. Many jurisdictions set a minimum distance from a property line, and many set a floor area or a height above which a permit is required. Both are local, both are cheap to check in advance, and both are expensive to discover after the structure is up. We have not published a threshold here because they vary too widely to state as fact.
Finally, think about access — for building it and for using it. A shed reached only by carrying things across a lawn will be used less than one you can wheel a mower into. And if you ever want power or water out there, running the service is far cheaper while the ground is already open than as a second project two years later.
Kit, flat-pack or built on site
Three routes lead to the same shed and they price very differently, mostly because of how much labour is embedded in the product before it reaches you.
A flat-pack kit is the cheapest and the most variable in quality — the panels are thin, the fixings are minimal, and the result depends heavily on the base beneath it. A better-grade kit uses real framing and a proper roof covering, and it costs more because there is more material in the box.
Building on site costs most in labour and least in compromise. It is the only route that lets you match an existing roofline, work around an awkward footprint, or specify a floor that will take real weight.
The comparison people get wrong is treating assembly time as free. A kit that takes two people a full weekend has consumed real time, and if the base has to be prepared first, that is another day. Price the route on the finished, usable structure rather than on the box.
Size the doors for what goes in
One dimension is worth settling before anything else is ordered, because it cannot be corrected afterwards without rebuilding a wall: the door opening.
A shed sized generously but fitted with a narrow single door will not take a ride-on mower, a wheelbarrow or sheet material, and those are frequently the exact things it was built to hold. Double doors, or a single wide leaf, cost very little extra at build time and determine what the building is actually useful for.
Measure the widest thing you expect to store, add clearance for hands and handles, and specify the opening from that rather than from what the standard kit happens to include.
Methodology
All dollar figures are computed directly from this calculator's own per-sq-ft rates for shed material, shed labor, foundation material, and foundation labor by build type and foundation type — no figure here is estimated or interpolated beyond that arithmetic. Carpentry wage data is the BLS OEWS May 2025 national estimate for SOC 47-2031. No frost-line depth, footing spec, or permit-size threshold is stated, because none is held by this calculator's module or independently verified for this page.
Sources
- U.S. Bureau of Labor Statistics — OEWS Profile, Carpenters (47-2031), May 2025 — accessed 2026-09-07