Shed Cost Calculator

A prefab 10×12 with delivery, set labor, a gravel pad, two windows and a door runs about $3,760 installed; the same size as a kit you assemble is around $2,920 in materials, and a custom stick-built 10×12 lands near $6,040. Adding a concrete slab instead of gravel moves a prefab build to roughly $4,240.

Usually not until you cross 120 sq ft — the IRC's permit exemption for one-story detached accessory structures stops there, and most IRC-based city codes follow it. Expect a building permit (we model $175) for 121–200 sq ft, and plan review around $450 over 200 sq ft. Running power changes the math: an electrical permit is required in most jurisdictions no matter how small the shed is.

Yes, by a wide margin for the same size and finish — our 10×12 numbers come out to $3,760 prefab versus $6,040 stick-built, about 38% less. What prefab buys less of is control: custom framing lets you match your house, add a loft, or go taller than stock wall panels.

For a storage shed, a compacted 4–6 in. gravel pad is the value pick — it drains, it levels a sloped yard, and it costs a fraction of concrete ($480 vs $960 for a 10×12, installed). Choose a slab when the shed holds vehicles or heavy equipment, when frost heave is severe, or when the structure might ever become conditioned space.

About $1,200 for a single 20A circuit (lights, outlets, a battery charger) and $2,800 for a 60–100A subpanel that can run tools, a mini-split or a welder, including trenching to roughly 50 ft. Distance is the swing factor: underground runs price out around $5–$12 per linear foot once the trench gets long.

Don't — soil that holds moisture rots floor joists and lets the building rack as the ground softens, and most manufacturers void the warranty the day a shed sits on bare dirt. The good news is that proper bearing is the cheapest line in this calculator: pier blocks on footings actually run about $180 less than a gravel pad on a 10×12 ($3,580 vs $3,760 whole-build) because there's little to buy or haul — they just need level, firm ground. Gravel handles slope and drainage; only pay slab money ($4,240 for the same shed) when it holds vehicles, heavy equipment or future living space.

Prefab is the same-day option: the building arrives on a truck and is crane-placed or rolled onto the pad — our 12×16 prefab (192 sq ft) prices at about $5,767 delivered and set, crew gone by dinner. A panelized kit is a weekend or two of homeowner assembly with a helper. A custom stick-built shed — about $9,343 for the same 12×16 — usually takes a two-person crew 1–3 weeks including the foundation and roof, and it needs the building permit approved before anyone digs.