DIY vs Hire Shed Building: Cost Comparison Calculator

Is DIY cheaper for a shed?

On the defaults — a 120 sq ft shed, $20.00 of materials per sq ft, $300 of supplies, 30 hours at $45 an hour, against a pro quote of $45.00 per sq ft — building it yourself costs $4,050.00 against a $5,400.00 pro quote: DIY wins by $1,350.00. A pro shed build usually runs $30–$60 per sq ft installed, a prefab kit $15–$30 per sq ft plus assembly, and a custom build more; a 120 sq ft pro job commonly costs $3,600–$7,200. A typical shed is 80–200 sq ft, so a 120 sq ft shed is a middle-of-the-road job — big enough to matter, small enough to build yourself. DIY is worth it when the shed is small and simple, the ground is flat, the shape is a plain rectangle and you have a helper; hire a pro for a large or custom shed, sloped ground, electrical work, tight deadlines, or a job that needs a permit and inspection — and the pro's labour warranty.

Three things about the model are worth stating plainly. First, the DIY cost is 120 × $20.00 + $300 + 30 × $45 = $4,050.00. Second, the pro cost is 120 × $45.00 = $5,400.00. And third, DIY wins by $1,350.00; all listed in Accuracy & limitations.

The worked example, line by line

Setup: 120 sq ft shed, $20.00 of materials per sq ft, $300 of supplies, 30 hours at $45 an hour, pro quote $45.00 per sq ft.

Line 1 — the DIY cost. The DIY cost is 120 × $20.00 = $2,400.00 of materials, + $300.00 of supplies, + 30 × $45.00 = $1,350.00 of labour = $4,050.00.

Line 2 — the pro cost. The pro cost is 120 × $45.00 = $5,400.00.

Line 3 — who wins. $5,400.00 − $4,050.00 = $1,350.00, so DIY wins by $1,350.00.

Line 4 — the check. $2,400.00 + $300.00 + $1,350.00 = $4,050.00, the DIY cost; and $5,400.00 − $4,050.00 = $1,350.00, the DIY win.

Every branch, checked

Hours 20: DIY $3,600.00; pro $5,400.00 — DIY wins by $1,800.00 — With 20 hours instead of 30 the DIY cost falls to $3,600.00 and DIY wins by $1,800.00.

Hours 45: DIY $4,725.00; pro $5,400.00 — DIY wins by $675.00 — With 45 hours the DIY cost rises to $4,725.00 and DIY wins by $675.00.

Materials $15.00: DIY $3,450.00; pro $5,400.00 — DIY wins by $1,950.00 — With materials at $15.00 per sq ft the DIY cost falls to $3,450.00 and DIY wins by $1,950.00.

Materials $30.00: DIY $5,250.00; pro $5,400.00 — DIY wins by $150.00 — With materials at $30.00 per sq ft the DIY cost rises to $5,250.00 and DIY wins by only $150.00.

Hours 60: DIY $5,400.00; pro $5,400.00 — exact tie — With 60 hours the DIY cost is $5,400.00, exactly the pro cost — a dead heat, a TIE.

Materials $31.25: DIY $5,400.00; pro $5,400.00 — exact tie — With materials at $31.25 per sq ft the DIY cost is $5,400.00, exactly the pro cost — a dead heat, a TIE.

Hours 40: DIY $4,500.00; pro $5,400.00 — DIY wins by $900.00 — With 40 hours the DIY cost is $4,500.00 and DIY wins by $900.00.

The reverses, worked backwards

Smallest hourly value where hiring WINS: At the displayed $91 the figures are DIY $5,430.00; pro $5,400.00 — Hiring wins by $30.00. At the displayed $91 the DIY cost is $5,430.00 against a $5,400.00 pro quote, so hiring wins by $30.00. At $90 the DIY cost is $5,400.00, exactly the pro cost — a dead heat, a TIE — so $91 is the smallest hourly value where hiring wins.

Largest hourly value where DIY still wins by at least $500: At the displayed $73 the figures are DIY $4,890.00; pro $5,400.00 — DIY wins by $510.00. At the displayed $73 the DIY cost is $4,890.00 and DIY wins by $510.00. At $74 the DIY cost is $4,920.00 and DIY wins by only $480.00 — under the $500 target — so $73 is the largest hourly value where DIY still wins by at least $500.

Smallest supplies where hiring WINS: At the displayed $1,651 the figures are DIY $5,401.00; pro $5,400.00 — Hiring wins by $1.00. At the displayed $1,651 the DIY cost is $5,401.00 against a $5,400.00 pro quote, so hiring wins by $1.00. At $1,650 the DIY cost is $5,400.00, exactly the pro cost — a dead heat, a TIE — so $1,651 is the smallest supplies where hiring wins.

Smallest whole-cent materials where hiring WINS: At the displayed $31.26 the figures are DIY $5,401.20; pro $5,400.00 — Hiring wins by $1.20. At the displayed $31.26 the DIY cost is $5,401.20 against a $5,400.00 pro quote, so hiring wins by $1.20. At $31.25 the DIY cost is $5,400.00, exactly the pro cost — a dead heat, a TIE — so $31.26 is the smallest whole-cent materials where hiring wins.

Smallest hours where hiring WINS: At the displayed 61 the figures are DIY $5,445.00; pro $5,400.00 — Hiring wins by $45.00. At the displayed 61 hours the DIY cost is $5,445.00 against a $5,400.00 pro quote, so hiring wins by $45.00. At 60 hours the DIY cost is $5,400.00, exactly the pro cost — a dead heat, a TIE — so 61 is the smallest hours where hiring wins.

Smallest pro price per sq ft where DIY wins at all: At the displayed $34 the figures are DIY $4,050.00; pro $4,080.00 — DIY wins by $30.00. At the displayed $34 per sq ft the pro cost is $4,080.00 against a $4,050.00 DIY cost, so DIY wins by $30.00. At $33 per sq ft the pro cost is $3,960.00 and hiring wins by $90.00 — so $34 is the smallest pro price where DIY wins at all.

A warning about the neighbours: every neighbour above sits one step from the star — $1 of supplies, one cent of materials, one hour, one dollar of hourly value, one dollar of pro price. A pro quote that moves by a dollar changes the answer. The page prints the neighbour values in full so the rounding does not mislead you: at $90 the DIY cost is $5,400.00, a dead heat; at $74 DIY wins by only $480.00; at $1,650 the DIY cost is $5,400.00, a dead heat; at $31.25 the DIY cost is $5,400.00, a dead heat; at 60 hours the DIY cost is $5,400.00, a dead heat; at $33 per sq ft the pro cost is $3,960.00 and hiring wins by $90.00.

What the defaults assume

The defaults are a 120 sq ft shed, $20.00 of materials per sq ft, $300 of supplies, 30 hours at $45 an hour, and a pro quote of $45.00 per sq ft — DIY $4,050.00; pro $5,400.00 — DIY wins by $1,350.00. With Hours 20, DIY $3,600.00; pro $5,400.00 — DIY wins by $1,800.00. With Hours 45, DIY $4,725.00; pro $5,400.00 — DIY wins by $675.00. With Materials $15.00, DIY $3,450.00; pro $5,400.00 — DIY wins by $1,950.00. With Materials $30.00, DIY $5,250.00; pro $5,400.00 — DIY wins by $150.00. With Hours 60, DIY $5,400.00; pro $5,400.00 — exact tie. With Materials $31.25, DIY $5,400.00; pro $5,400.00 — exact tie. With Hours 40, DIY $4,500.00; pro $5,400.00 — DIY wins by $900.00. With All zero, DIY $0.00; pro $0.00 — exact tie. With 60 sq ft, materials $15.00, supplies $100, hours 8, hourly $30, pro $40.00, DIY $1,240.00; pro $2,400.00 — DIY wins by $1,160.00. With 100 sq ft, materials $18.375, supplies $215.75, hours 12.5, hourly $42.25, pro $38.50, DIY $2,581.38; pro $3,850.00 — DIY wins by $1,268.63. With Materials $40.00, supplies $600, hours 50, hourly $80, pro $45.00, DIY $9,400.00; pro $5,400.00 — Hiring wins by $4,000.00. With Hours 0, DIY $2,700.00; pro $5,400.00 — DIY wins by $2,700.00. With Hours 12.5, DIY $3,262.50; pro $5,400.00 — DIY wins by $2,137.50. With Who-wins bars, hourly value for a $600.00 DIY win $70.00; pro price per square foot for a $1,200.00 DIY win $43.75; materials per square foot for a $900.00 DIY win $23.75.

A note on the rounding: with 100 sq ft, materials $18.375, supplies $215.75, 12.5 hours at $42.25 an hour and a pro price of $38.50 per sq ft, the unrounded DIY cost is 2581.375 — which rounds half-up to $2,581.38 — and the unrounded win is 1268.625 — which rounds half-up to $1,268.63. The page prints the unrounded values so the rounding does not mislead you.

Output · formula · meaning

Who uses this

• The homeowner with a flat garden: they learn building a 120 sq ft shed themselves costs $4,050.00 against a $5,400.00 pro quote — and they check the $91 reverse to see the hourly value where hiring wins.
• The DIYer pricing a kit: they learn a prefab kit runs $15–$30 per sq ft plus assembly — and they check the $31.26 reverse to see the materials price where hiring wins.
• The busy parent with no weekends free: they learn a pro crew finishes in a day while a DIYer takes several weekends — and they check the 61 reverse to see the hours where hiring wins.
• The buyer comparing quotes: they learn a 120 sq ft pro job commonly costs $3,600–$7,200 — and they check the $34 reverse to see the pro price where DIY wins at all.

Accuracy & limitations

The math is first-principles: the DIY cost is sq ft × materials per sq ft + supplies + hours × hourly value; the pro cost is sq ft × pro price per sq ft; the winner is the lower cost, and equal costs are a dead heat — all rounded to two decimals half-up. What the model cannot do is price your shed: pro prices vary by region and by finish — $30–$60 per sq ft installed, a prefab kit $15–$30 per sq ft plus assembly, a custom build more; materials vary by grade; the hourly value is your own time, so price it honestly — an hour of your weekend is worth more than an hour you would spend idle. The model also cannot see the ground: an unlevel foundation so the door will not close, an unflashed roof that leaks, and building too close to the property line — which can bring a fine — are all risks the calculator cannot price; and it does not include permits, inspections or a pro's labour warranty. Use it to see the money — then walk the ground before you decide.

Frequently asked questions