How many metal roof panels for a 30×40 roof?

Data checked October 2026

Short answer

A 30×40 ft gable roof at 4/12 with 12-in overhangs needs 28 panels of 36-in coverage (14 per side), each 16' 11" long, plus about 1,134 screws.

Panels per side: 42 ft along the eave (overhangs included) ÷ 3 ft of coverage = 14, rounded up to 14.
Panel length: 16 ft of run per side × 1.054 (4/12 multiplier) = 16' 11", to the next inch.
Store panels come in fixed lengths, so you'd buy 28 × 20-ft panels ($80.99 each) and trim about 37 in off each: $2,268 versus about $1,918 cut to length.
Trim: 5 ridge caps (10½ ft, lapped to 10), 9 pieces of eave trim, 7 of rake trim, and 56 foam closure strips for the eaves and ridge.
In 5V crimp (24-in coverage) the same roof takes 42 panels — 14 more to haul and screw, about $2,394 in panels.
Weight: about 992 lb of 29-ga panels — roughly 70 lb per square, versus about 220 lb per square for architectural shingles.
30×40 is a common pole-barn and shop size; its 16' 11" panels fall between the 16- and 20-ft stock lengths, so stock panels waste about 3 ft each.

Adjust it to your exact job

Building

Roof shape

Lengthalong the eave

= 40' · 12.19 m

Widtheave to eave

= 30' · 9.14 m

Pitch

Exact pitch

/12

Multiplier 1.054

Eave overhang

= 1'

Gable overhang

= 1'

Panels

Profile

Panel lengths

Solid deck with underlayment

Turn off for panels screwed straight to purlins (pole barns, open sheds).

Panels to order

28× 16' 11"

14 per side × 2 sides · 36-in coverage · 474 lin ft of panel

Roof area: 1,417sq ft14.2 squares
Screws: 1,13480 per square, panels only
Panel run (cut): 16' 11"eave edge to ridge, along the slope
Panel weight: 992lb29 ga at 0.70 lb/sq ft

Trim & closures

Trim pieces and closure strips
Item	Length	Buy
Ridge cap	42 ft	5 × 10½ ft
Eave trim	84 ft	9 × 10½ ft
Rake trim	68 ft	7 × 10½ ft
Inside closures (eave)	84 ft	28 × 36 in
Outside closures (ridge)	84 ft	28 × 36 in

Compare panel profiles

Panels by profile
Profile	Panels	Lin ft	Panel cost
36-in rib panel36-in coverage	28	474	$1,918
5V crimp24-in coverage	42	711	$2,394

Screw pattern

Fabral calls for 80 screws per square on exposed-fastener rib panels: screws at the eaves, ridge and end laps, and at every intermediate support. Drive them snug — an over-tightened washer leaks as surely as a loose one. Trim and side-lap stitch screws come on top of this count.

Shopping list

28 panels 36-in rib panel panels, 16' 11" cut to length14 per side at 36-in coverage · 474 lin ft$1,918
1,134 screws #14 × 1 in Woodtite roofing screws (OSB/plywood deck)80 per square; use #10 × 1½ in into purlins
5 pieces Ridge cap, 10½ ft × 14 in42 ft, lapped 6 in$185
9 pieces Eave trim / drip edge, 10½ ft84 ft
7 pieces Rake (gable) trim, 10½ ft68 ft
28 strips Inside foam closure, 36 in (eaves)$78.12
28 strips Outside foam closure, 36 in (ridge)$78.12
2 rolls Synthetic underlayment, 10-sq roll (42 in × 286 ft)$260
1 buckets 1-in plastic cap nails, bucket of 3,000$45.49

Estimated total$2,565

Cost estimate

Tap a price to use your store's

36-in rib panel panel, cut to length (29 ga)
473.7 lin ft × $
$1,918
Ridge cap, 10½ ft
5 pieces × $
$185
Foam closure strips, 36 in
56 strips × $
$156
Synthetic underlayment, 10-sq roll (42 in × 286 ft)
2 rolls × $
$260
Plastic cap nails (3,000)
1 buckets × $
$45.49

Materials total$2,565

29 ga Galvalume prices from McCoy's (San Marcos, TX), Oct 23, 2026; cut-to-length uses the same per-foot rate. Eave and rake trim vary by supplier — get a quote with the panels.

Did this answer your question?

Compare

The same 30×40 roof at other pitches

Pitch	Panel length	Panels	Roof sq ft	Screws	Panel cost
3/12	16' 6"	28	1,385	1,109	$1,871
4/12	16' 11"	28	1,417	1,134	$1,918
5/12	17' 4"	28	1,456	1,165	$1,966
6/12	17' 11"	28	1,503	1,203	$2,032
8/12	19' 3"	28	1,615	1,293	$2,183

How this was worked out

Roof area: 42 × 32 ft of plan × 1.054 = 1,417 sq ft (14.2 squares). At Fabral's 80 screws per square that's 1,134 panel screws — #14 × 1 in Woodtite into a plywood or OSB deck, #10 × 1½ in into purlins — before trim and stitch screws.

Under 3/12 the IRC requires lap sealant on exposed-fastener panels; 36-in rib panels are rated down to 2½/12 by their makers and 5V crimp to 3/12. At 4/12 either profile is fine without sealant.

The full method, material data and tips are on the main metal roofing calculator page.

Similar jobs

Other sizes people check

Sources

Data behind this answer

Fabral Grandrib 3 product specification — 36-in coverage, 2½:12 minimum, 80 screws per square; cut to length up to 40 ft · checked October 2026
Best Buy Metals Tuff-Rib and 5V crimp — 36-in coverage cut to the inch 3–45 ft; 29 ga 0.70 lb/sq ft; 5V 24-in coverage, 3:12 minimum · checked October 2026
McCoy's metal roofing (Metal Sales StrongPanel, 5V, ridge cap, closures) — 8–20 ft panel prices, 10½-ft ridge cap $36.99, closure strips $2.19–2.79 — 2026-10-23 · checked October 2026
2024 International Residential Code R905.10 (UpCodes) — lapped metal panels 3:12 minimum (½:12 with lap sealant; standing seam ¼:12) · checked October 2026
Owens Corning ProArmor synthetic underlayment — 929 sq ft net per roll with 3-in laps · checked October 2026

Short answer

A 30×40 ft gable roof at 4/12 with 12-in overhangs needs 28 panels of 36-in coverage (14 per side), each 16' 11" long, plus about 1,134 screws.

Panels per side: 42 ft along the eave (overhangs included) ÷ 3 ft of coverage = 14, rounded up to 14.

Panel length: 16 ft of run per side × 1.054 (4/12 multiplier) = 16' 11", to the next inch.

Store panels come in fixed lengths, so you'd buy 28 × 20-ft panels ($80.99 each) and trim about 37 in off each: $2,268 versus about $1,918 cut to length.

Trim: 5 ridge caps (10½ ft, lapped to 10), 9 pieces of eave trim, 7 of rake trim, and 56 foam closure strips for the eaves and ridge.

In 5V crimp (24-in coverage) the same roof takes 42 panels — 14 more to haul and screw, about $2,394 in panels.

Weight: about 992 lb of 29-ga panels — roughly 70 lb per square, versus about 220 lb per square for architectural shingles.

30×40 is a common pole-barn and shop size; its 16' 11" panels fall between the 16- and 20-ft stock lengths, so stock panels waste about 3 ft each.

Adjust it to your exact job

Building

Roof shape

Lengthalong the eave

= 40' · 12.19 m

Widtheave to eave

= 30' · 9.14 m

Pitch

Exact pitch

/12

Multiplier 1.054

Eave overhang

= 1'

Gable overhang

= 1'

Panels

Profile

Panel lengths

Solid deck with underlayment

Turn off for panels screwed straight to purlins (pole barns, open sheds).

Panels to order

28× 16' 11"

14 per side × 2 sides · 36-in coverage · 474 lin ft of panel

Roof area: 1,417sq ft14.2 squares
Screws: 1,13480 per square, panels only
Panel run (cut): 16' 11"eave edge to ridge, along the slope
Panel weight: 992lb29 ga at 0.70 lb/sq ft

Trim & closures

Trim pieces and closure strips
Item	Length	Buy
Ridge cap	42 ft	5 × 10½ ft
Eave trim	84 ft	9 × 10½ ft
Rake trim	68 ft	7 × 10½ ft
Inside closures (eave)	84 ft	28 × 36 in
Outside closures (ridge)	84 ft	28 × 36 in

Compare panel profiles

Panels by profile
Profile	Panels	Lin ft	Panel cost
36-in rib panel36-in coverage	28	474	$1,918
5V crimp24-in coverage	42	711	$2,394

Screw pattern

Shopping list

28 panels 36-in rib panel panels, 16' 11" cut to length14 per side at 36-in coverage · 474 lin ft$1,918
1,134 screws #14 × 1 in Woodtite roofing screws (OSB/plywood deck)80 per square; use #10 × 1½ in into purlins
5 pieces Ridge cap, 10½ ft × 14 in42 ft, lapped 6 in$185
9 pieces Eave trim / drip edge, 10½ ft84 ft
7 pieces Rake (gable) trim, 10½ ft68 ft
28 strips Inside foam closure, 36 in (eaves)$78.12
28 strips Outside foam closure, 36 in (ridge)$78.12
2 rolls Synthetic underlayment, 10-sq roll (42 in × 286 ft)$260
1 buckets 1-in plastic cap nails, bucket of 3,000$45.49

Estimated total$2,565

Cost estimate

Tap a price to use your store's

36-in rib panel panel, cut to length (29 ga)
473.7 lin ft × $
$1,918
Ridge cap, 10½ ft
5 pieces × $
$185
Foam closure strips, 36 in
56 strips × $
$156
Synthetic underlayment, 10-sq roll (42 in × 286 ft)
2 rolls × $
$260
Plastic cap nails (3,000)
1 buckets × $
$45.49

Materials total$2,565

29 ga Galvalume prices from McCoy's (San Marcos, TX), Oct 23, 2026; cut-to-length uses the same per-foot rate. Eave and rake trim vary by supplier — get a quote with the panels.

Pitch

Panel length

Panels

Roof sq ft

Screws

Panel cost

3/12

16' 6"

1,385

1,109

$1,871

4/12

16' 11"

1,417

1,134

$1,918

5/12

17' 4"

1,456

1,165

$1,966

6/12

17' 11"

1,503

1,203

$2,032

8/12

19' 3"

1,615

1,293

$2,183

How this was worked out

Under 3/12 the IRC requires lap sealant on exposed-fastener panels; 36-in rib panels are rated down to 2½/12 by their makers and 5V crimp to 3/12. At 4/12 either profile is fine without sealant.

The full method, material data and tips are on the main metal roofing calculator page.