Estimating Calculator Formula

Understand the math behind the estimating calculator. Each variable explained with a worked example.

Use the Estimating Calculator

Formulas Used

Base Material Cost

base_cost = quantity * unit_cost

Cost with Waste

cost_with_waste = quantity * unit_cost * (1 + waste_pct / 100)

Total with Markup

total_cost = quantity * unit_cost * (1 + waste_pct / 100) * (1 + markup_pct / 100)

Quantity to Order (with waste)

quantity_with_waste = ceil(quantity * (1 + waste_pct / 100))

Variables

VariableDescriptionDefault
quantityQuantity Needed500
unit_costUnit Cost(USD)12
waste_pctWaste Factor(%)10
markup_pctMarkup(%)25

How It Works

How to Estimate Material Costs

Formula

Total = Quantity x Unit Cost x (1 + Waste%/100) x (1 + Markup%/100)

Waste factor accounts for cuts, breakage, defects, and installation waste. Markup covers your profit and overhead on materials.

Worked Example

500 square feet of tile at $12/sq ft with 10% waste and 25% markup.

quantity = 500unit_cost = 12waste_pct = 10markup_pct = 25
  1. 01Base material cost = 500 x $12 = $6,000
  2. 02Cost with 10% waste = $6,000 x 1.10 = $6,600
  3. 03Total with 25% markup = $6,600 x 1.25 = $8,250
  4. 04Quantity to order = 500 x 1.10 = 550 sq ft

Ready to run the numbers?

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