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Roofing bid price calculator

Your material prices, your labour rate, your overhead, your profit. It shows the bid, the price per square, and what your chosen profit rate actually earns — because markup and margin are not the same number.

1. The roof

Roof style

13.42 squares. See the full takeoff →

2. Your costs

Every price starts empty on purpose. A bid built on someone else’s guess at material prices is worse than no bid — put in what your own supplier charges you.
Labour

3. Your price

Your trucks, insurance, office and phone. Separate from profit.

Profit basis

Margin is a share of the PRICE. price = cost ÷ (1 − margin).

A 35.0% margin is a 53.8% markup.

Tax applies to

Many states tax materials but not labour on a re-roof. Check your own.

Bid

Put your supplier’s price against each of these and the bid appears. They are not guessed for you: a bid built on someone else’s idea of what shingles cost is worse than no bid.

  • Architectural (laminated)
  • Synthetic underlayment (10 sq roll)
  • Plastic cap nails — 1 in plastic cap nails, 2,000 per box
  • Starter strip — Owens Corning Starter Strip Plus, split (105 ft)
  • Hip and ridge cap — GAF Seal-A-Ridge (25 ft)
  • Drip edge (10 ft pieces)
  • Roofing nails — Coil carton (7,200 nails, approx. 31 lb)
The formula
direct cost = materials + tear-off + labour + disposal + permit total cost = direct cost × (1 + overhead) MARKUP: price = total cost × (1 + markup) a share of COST MARGIN: price = total cost ÷ (1 − margin) a share of PRICE markup = margin ÷ (1 − margin) margin = markup ÷ (1 + markup)

Overhead and profit are two different things and are applied in that order. Overhead is what the business costs to run whether or not this job happens — trucks, insurance, the phone, the office. Profit is what is left after that. Rolling them into one number is how a contractor ends up busy and broke.

Then the profit basis, which is the part worth being careful about. Markup is measured against cost; margin is measured against price. A 50% markup on $1,000 of cost gives a $1,500 price and a 33.3% margin. A 50% margin on the same cost gives $2,000 and a 100% markup. They coincide only at zero. This calculator asks which one you mean, and then shows you both, so a number you typed can never quietly mean the other thing.

Worked example: bidding the 40 × 30 gable
Roof
13.42 sq (40 × 30 at 6/12)
Materials
$2,380.50
Labour
$155 a square
Overhead
10%
Profit
35% margin
  1. Materials. The takeoff's order at the contractor's own prices: 45 bundles at $36.50, 2 rolls at $110, 2 starter at $55, 2 cap at $48, 16 drip edge at $12, 1 carton of nails at $120, 1 box of plastic cap nails at $45 — $2,425.50.
  2. Tear-off. 13.4164 squares × 1 layer × $55.00 = $737.90.
  3. Install labour. 13.4164 squares × $155.00 = $2,079.54.
  4. Disposal and permit. $450.00 and $250.00.
  5. Direct cost. $2,425.50 + $737.90 + $2,079.54 + $450 + $250 = $5,942.94.
  6. Overhead. 10% of $5,942.94 = $594.29, so the total cost is $6,537.23.
  7. Price at a 35% margin. $6,537.23 ÷ (1 − 0.35) = $10,057.28. That is $749.63 a square.
  8. The same 35% as a markup. $6,537.23 × 1.35 = $8,825.26 — $1,232.02 less, on one average residential roof, and it earns a 25.9% margin rather than the 35% the contractor had in mind.
  9. Spread across the lines. Overhead and profit are then spread across the cost lines in proportion, so the itemised estimate adds up to $10,057.28 exactly. Nothing is parked on one line to make the total come out.

$10,057.28 at a 35% margin, or $749.63 a square. The same rate entered as a markup would have bid $8,825.26 — $1,232.02 of profit given away on one roof.

Figures from Markup and margin are definitions, not measurements — see the sources page; The takeoff this bid is built on.

Questions

Should I price on markup or on margin?
Margin, if you are thinking about the health of the business, because margin is the share of the money coming in that you keep and it is the number that compares to anything else you read. Markup is easier to apply in your head at the van. The important thing is not which you pick but that you know which one you picked — this calculator shows both, every time, so the two cannot be confused.
Why are all the material prices blank?
Because we do not know what your supplier charges you, and a bid built on a stranger's guess at material prices is worse than no bid at all. The grey text in each field shows the shape of the number and the unit it wants, not a value we are suggesting.
What should overhead be?
It is your figure: last year's fixed costs divided by last year's revenue is the usual way to arrive at it. Ten per cent is a common starting point for a small crew, but a company with more trucks, more insurance and an office carries more. The point of keeping it separate from profit is that you can see what the job costs to do before you decide what to earn on it.
Do the itemised lines add up to the bid?
Exactly, to the cent. The markup is spread across the cost lines in proportion, each line is rounded to whole cents, and the rounding residue — a cent or two — is assigned to the largest line. An estimate whose lines do not add up to the total printed under them is an estimate the customer stops trusting, so this is tested rather than assumed.
Is sales tax on labour?
It depends on your state, and on whether the job is a repair or a capital improvement. Many states tax materials and not labour on a re-roof, which is the default here, but it is a genuine choice and the toggle is there because we cannot make it for you. Check your own rules.
What does it not include?
Anything you have not told it about: steep-pitch and height charges, decking replacement you will not know about until the roof is open, detach-and-reset for satellite dishes or solar, specialist flashing, and your own travel. The storm and insurance checklist lists the items that most often get left off a scope.
Roofing bid price calculator · RoofParrot