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Roof Sheet Quantity Calculator

Work out roof sheet quantity instantly with clear inputs, formula shown and shareable results.

About Roof Sheet Quantity Calculator

Profiled sheeting is counted by effective cover width, not by overall width, because one rib overlaps the next. Across the roof the count is length divided by cover width; up the slope each row loses about 200 mm to end lap, so the usable sheet length is reduced before dividing into the rafter length.

Formulas

Sheets across

Count = ceil(roof length / effective cover width)

Rows

Rows = ceil(rafter length / (sheet length - 0.2 m end lap))

Worked example

With the default values below, Roof Sheet Quantity Calculator returns Sheets required of 24. Change any input above and every figure here is recalculated in your browser.

Inputs used

Roof length along eavesminimum 0.1 m
12 m
Rafter length up the slopeminimum 0.1 m
5 m
Sheet effective cover widthminimum 0.1 m
1 m
Sheet lengthminimum 0.3 m
3 m

Results

Sheets required
24
Sheets across the roof
12
Rows up the slope
2
Roof slope area
60.00 m²

Step by step

  1. 1Values used
  2. 2Sheets across
  3. 3Rows
  4. 4Sheets required= 24
  5. 5Sheets across the roof= 12
  6. 6Rows up the slope= 2
  7. 7Roof slope area= 60.00 m²

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Roof Sheet Quantity figure worked out?

Count = ceil(roof length / effective cover width). Profiled sheeting is counted by effective cover width, not by overall width, because one rib overlaps the next.

Does the roof pitch change the quantity?

It changes the rafter length, which is longer than the plan dimension by the pitch multiplier. Measure or calculate the true slope length rather than the plan projection.

What values do I need to enter?

This calculator takes 4 inputs: Roof length along eaves, Rafter length up the slope, Sheet effective cover width, Sheet length. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

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