Why ask for exposure rather than the covering's length?

Because the length is not what decides how many courses a roof takes. Every course overlaps the one below by enough to keep water out, so the part of each unit actually on view — the exposure, or gauge — is the length minus that headlap. The headlap is not a property of the covering alone: it grows on shallower pitches and on exposed sites, because both give wind-driven rain more chance to travel up under the lap. So the same tile on a 45-degree roof and on a 22-degree roof has two different exposures, two different course counts and two different fixing totals. A calculator that took the nominal length would give the same answer for both and be wrong for at least one.

Why are the perimeter zones fixed more heavily?

Because that is where the wind pulls hardest. Air flowing over a building separates at its edges and corners and generates strong local suction there — several times the pressure over the middle of the roof — so the units along an eaves, a verge, a ridge and especially at a corner are the ones most likely to be lifted. Fixing specifications answer that by tightening the pattern in defined zones rather than by fixing the whole roof to the worst case, which would be wasteful. The practical consequence is that the zone WIDTH matters as much as the fixing count: it comes out of the building's dimensions and height in the wind standard, and on a small or a tall building it can cover far more of the roof than people assume.

The count looks high — is that right?

Probably, and it is the reason this page exists. A standard square of three-tab shingles at four nails each is about 320 nails, and the same square in a high-wind pattern at six is about 480. A modest house roof runs into five figures. Counts that size are why fixings get ordered by weight rather than by number, and why running short mid-slope is a common and expensive way to lose a day — the roof cannot be left part-fixed overnight in weather.

Does this cover clips as well as nails?

It counts FIXINGS, whatever they are, as long as you enter the pattern correctly — and the pattern is where clips differ. Many interlocking tiles are held by a clip engaging the side of the tile rather than a nail through it, and specifications often call for every tile clipped in the perimeter and a proportion clipped in the field. Where the field pattern is every third or fourth tile, the field figure here is less than one per unit, and the way to express that is to work out the effective rate and round up rather than entering 1 and over-ordering. What this page cannot do is mix two fixing types on one run, so a roof that is nailed at the head and clipped at the side is two calculations.

Renovation & Construction

Roof Covering Fixing Calculator

Count the nails, clips or screws holding a roof covering down, from the covering's width and exposure and a tighter pattern at the perimeter.

Answers as you typeNo submit button
Every formula citedNamed published standards
Calculated in your browserNo account, nothing uploaded

SettingsSettings for this calculationUS

Market

Imperial · sales tax

Who is doing the work?

Waste is set to 5% by hand. Pick a tier above to replace it, or keep your own figure.

Roof area

The area of covering, measured on the slope.

On the SLOPE, not the plan. A plan area understates a pitched roof by the pitch factor, and at 40 degrees that is about 30% of the fixings missing.

Covering width

The width of one unit as laid, measured along the course.

For an interlocking tile this is the COVERING width, which is narrower than the tile — the part of the lap that disappears under the next tile does not count. For a shingle it is the full width.

Exposure (gauge)

The visible part of each course — the batten gauge.

Covering length minus the headlap. The lap grows on shallower pitches and on exposed sites, which shortens the exposure and adds courses, so take this from the fixing specification for your pitch rather than from the covering's nominal length.

Fixings per unit, field

How many fixings each unit takes across the main area of the roof.

Asphalt shingles are commonly four in the field. Interlocking tiles are frequently clipped rather than every one nailed, so the effective figure can be one or even a fraction of one — round up rather than guessing below one.

Fixings per unit, perimeter

The tighter pattern at eaves, verges, ridge and corners.

Wind suction is highest at edges and corners, so specifications fix more there — often every unit mechanically fixed, and often two fixings where the field takes one. This is the number the roof's wind calculation produced, not a guess.

Perimeter zone share

Percentage of the roof area inside the tighter perimeter zones.

The zone width comes from the building's dimensions and height in the wind standard, not from a rule of thumb. On a small simple roof it can be most of the area; on a large simple one it is a narrow band. Twenty per cent is a starting point for a typical house, not an answer.

Waste Allowance (%)

Spare fixings for the ones dropped off the roof or bent going in.

Fixings are small and handled at height, so some are always lost. This covers that loss and nothing else: a nail gun set to over-drive, or a pattern entered too light, is not an allowance problem and no percentage here fixes it.

Fixings needed

1,620 fixings

Medium confidence

0.60 units per sq ft at the width and exposure entered. The 5% allowance is for dropped and bent fixings; the perimeter share is the number you entered and is the input most worth checking against the wind calculation.

Units per sq ft: 0.6 units/sq ft
Units in total: 644 units
Field fixings: 1,031 fixings
Perimeter fixings: 516 fixings

Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

Units per square metre are geometry, not a product table: a covering of width w laid at exposure e occupies w x e of roof, so the count is 1 / (w x e). A 1,000 mm wide covering at 143 mm exposure is 6.99 units per square metre; a 914 mm shingle at 127 mm exposure is 8.61, which is the 80-per-square figure quoted in North American practice
Exposure is the covering length minus the headlap the pitch and site exposure require, so the same covering on a shallower roof produces more courses and more fixings. It is entered rather than assumed
Fixing patterns tighten in perimeter zones because wind uplift concentrates at edges and corners, which is why the perimeter is a separate rate here rather than averaged into the field

Inputs used

Roof area: 1080 sq ft
Covering width: 3.5 ft
Exposure (gauge): 0.48 ft
Fixings per unit, field: 2 per unit
Fixings per unit, perimeter: 4 per unit
Perimeter zone share: 20
Waste Allowance (%): 5

Intermediate steps

Units per sq ft: 0.6 units/sq ft
Units in total: 644 units
Field fixings: 1,031 fixings
Perimeter fixings: 516 fixings

Final result1,623 fixings

Confidence note: 0.60 units per sq ft at the width and exposure entered. The 5% allowance is for dropped and bent fixings; the perimeter share is the number you entered and is the input most worth checking against the wind calculation.

What this calculation does not cover

Only the fixings through the covering are counted. Eaves and ridge accessories, hip irons, dry-verge components, clips holding a tile sideways rather than down, and the fixings for the battens or sheathing underneath are all separate items bought separately.
The perimeter share is taken as entered. Wind standards derive the zone width from the building's dimensions and height and it can be far larger than people expect on a small or a tall building — a 20% assumption on a roof whose zones are really 45% under-counts the fixings exactly where the roof is most likely to fail.
One exposure stands for the whole roof, so a slope with a shorter gauge at the eaves course, a doubled starter course, or a change of covering part way up is not described by a single figure.
Nothing here checks that the fixing itself is right. Length, material and head type are set by the covering, the batten or deck, the substrate and the exposure of the site, and a correct COUNT of the wrong nail is worse than useless on a roof.
The 5% allowance covers dropped and bent fixings. It does not cover a nail gun set badly, which over-drives and destroys far more than that and shows up as a count that runs out long before the roof does.
Hips, valleys and abutments consume cut units, and a cut unit still needs fixing — usually more than an uncut one, because the piece is smaller and has less to hold it. Area alone cannot see how much cutting a roof contains.

Estimated cost — your price

Price per fixing ($)

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Schematic, drawn to the proportions you entered — not to scale on screen.

Part of bigger jobs

This trade is one line of several job takeoffs. Run the whole job and every other trade comes back with it, off the same measurements.

Or plan the space itself: measure it once, doors and windows included, and this figure comes back worked out on that space, with what goes with it.

Room planner

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Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-27 · v1.1.0

Regulatory standards & verification citations3

Units per square metre are geometry, not a product table: a covering of width w laid at exposure e occupies w x e of roof, so the count is 1 / (w x e). A 1,000 mm wide covering at 143 mm exposure is 6.99 units per square metre; a 914 mm shingle at 127 mm exposure is 8.61, which is the 80-per-square figure quoted in North American practice
Exposure is the covering length minus the headlap the pitch and site exposure require, so the same covering on a shallower roof produces more courses and more fixings. It is entered rather than assumed
Fixing patterns tighten in perimeter zones because wind uplift concentrates at edges and corners, which is why the perimeter is a separate rate here rather than averaged into the field

Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Tools and safety for this job

To batten and tile or slate the roof. Generic types, no brands, no prices.

Protection this work requires

Cutting or grinding concrete, masonry, screed, tile or fibre-cement board releases respirable silica: cut wet or extract at the tool, and wear a P2/N95 respirator at minimum — a nuisance dust mask does not filter it.
Saws, grinders and breakers run above 85 dB, where hearing damage accumulates and does not recover: defenders or plugs for every cut, not just the long ones.
Breakers and grinders cause permanent nerve damage: limit continuous trigger time, keep hands warm, and stop if fingers tingle or blanch.
Boards, blocks and bagged material cause most lasting back injuries on small sites: two people or a lifter for full sheets, and never a bag on one shoulder up a ladder.
Most fatal falls on small jobs are from under three metres: use a tower or a ladder tied at the top, and never work off the top two rungs.

Show the 5 tools this job needs

Essential

Chalk line
Claw hammer
Hand saw
Tape measure

Recommended

Angle grinder

Also needed as materials: chalk refill, cutting and diamond discs.

what each roofing tool is for, and the spec that decides which to buy where one does.

Now that you have the number

These guides cover the work this quantity is for.

Called something else where you work? Roof valley — the term in each market, how close the equivalence really is, and the standard that governs it.

Worked example: Shingle roof replacement — step 8 of 11

Already gone wrong? Tiles or slates have slipped on my roof

The data behind it: Production rates by operation

How to calculate roof covering fixing in 8 steps

Roof areaThe area of covering, measured on the slope.
Covering widthThe width of one unit as laid, measured along the course.
Exposure (gauge)The visible part of each course — the batten gauge.
Fixings per unit, fieldHow many fixings each unit takes across the main area of the roof.
Fixings per unit, perimeterThe tighter pattern at eaves, verges, ridge and corners.
Perimeter zone sharePercentage of the roof area inside the tighter perimeter zones.
Waste Allowance (%)Spare fixings for the ones dropped off the roof or bent going in.
Fixings neededThe tool computes the fixings needed from those figures and shows the formula, its sources, and a confidence rating alongside it.

Fixings needed by roof area

Page defaults, not your figures above.

Roof area	Fixings needed (fixings)
500 sq ft	819
1,000 sq ft	1,638
1,500 sq ft	2,456
2,000 sq ft	3,275

Frequently asked questions

Why ask for exposure rather than the covering's length?: Because the length is not what decides how many courses a roof takes. Every course overlaps the one below by enough to keep water out, so the part of each unit actually on view — the exposure, or gauge — is the length minus that headlap. The headlap is not a property of the covering alone: it grows on shallower pitches and on exposed sites, because both give wind-driven rain more chance to travel up under the lap. So the same tile on a 45-degree roof and on a 22-degree roof has two different exposures, two different course counts and two different fixing totals. A calculator that took the nominal length would give the same answer for both and be wrong for at least one.
Why are the perimeter zones fixed more heavily?: Because that is where the wind pulls hardest. Air flowing over a building separates at its edges and corners and generates strong local suction there — several times the pressure over the middle of the roof — so the units along an eaves, a verge, a ridge and especially at a corner are the ones most likely to be lifted. Fixing specifications answer that by tightening the pattern in defined zones rather than by fixing the whole roof to the worst case, which would be wasteful. The practical consequence is that the zone WIDTH matters as much as the fixing count: it comes out of the building's dimensions and height in the wind standard, and on a small or a tall building it can cover far more of the roof than people assume.
The count looks high — is that right?: Probably, and it is the reason this page exists. A standard square of three-tab shingles at four nails each is about 320 nails, and the same square in a high-wind pattern at six is about 480. A modest house roof runs into five figures. Counts that size are why fixings get ordered by weight rather than by number, and why running short mid-slope is a common and expensive way to lose a day — the roof cannot be left part-fixed overnight in weather.
Does this cover clips as well as nails?: It counts FIXINGS, whatever they are, as long as you enter the pattern correctly — and the pattern is where clips differ. Many interlocking tiles are held by a clip engaging the side of the tile rather than a nail through it, and specifications often call for every tile clipped in the perimeter and a proportion clipped in the field. Where the field pattern is every third or fourth tile, the field figure here is less than one per unit, and the way to express that is to work out the effective rate and round up rather than entering 1 and over-ordering. What this page cannot do is mix two fixing types on one run, so a roof that is nailed at the head and clipped at the side is two calculations.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.