How the calculation works
The formulas
Line items multiply quantity by unit price and are grouped as materials, labour, or other. Contingency is calculated on the subtotal. Choose whether tax also applies to contingency; remaining budget subtracts the final total.
Line subtotal = quantity × unit price
Contingency = subtotal × contingency% / 100
Tax = (subtotal + selected contingency) × tax% / 100
Grand total = subtotal + contingency + tax
Assumptions to check
- Tax is a user-entered planning assumption, not a jurisdiction-specific tax determination. All values use one currency label.
- Sample unit prices are hypothetical. Zero means unpriced; no live prices or exchange rates are fetched.
A worked example
Materials 1,000 and labour 500 give 1,500. With 10% contingency and 5% tax including contingency, the total is 1,732.50 in the entered currency.