Finance category
Mortgage, loan, investing, tax, and money calculators.
New Construction Contingency Calculator
New construction projects typically run 10-20% over budget. Contingency reserve covers cost overruns, change orders, schedule slippage, and surprise site conditions. This calculator sizes the reserve. Soil conditions are the biggest hidden cost. Percolation tests, soil bearing, and watertable levels determine foundation design. Bad soil can add $20K-$80K to foundation cost unexpectedly. Utility connection fees (sewer, water, gas, electric tap-ins) routinely add New construction projects typically run 10-20% over budget. Contingency reserve covers cost overruns, change orders, schedule slippage, and surprise site conditions. This calculator sizes the reserve.5K-$50K beyond what contractors estimate. Budget at least 10% contingency for these site-specific unknowns before any above-grade work begins.
Recommended contingency reserve
$54,400
Cost overrun reserve
$48,000
Schedule slippage reserve
$6,400
Reserve as % of budget
13.6%
How the math works
$400K standard custom: 12% = $48K cost contingency + $6.4K schedule = $54.4K total. 13.6% of budget.
Most overruns come from change orders and surprise site conditions (bad soil, utility hookups). Minimize by freezing design before dig and insisting on fixed-price subcontractor contracts.
How to Use
- Enter base construction budget and expected build months.
- Enter your risk tolerance for cost overrun.
- See recommended contingency reserve.
Frequently Asked Questions
Typical contingency %?
10-15% on new custom builds. 7-10% on tract homes. 15-25% on complex sites (slope, unusual soil, historic). Start at 15% for most residential.
Who holds the contingency?
You do. Keep liquid in savings separate from construction loan draws. Lender includes contingency in approval but you control the discretionary spend.
If I don't need it?
Roll into furnishings, landscape, or pay down mortgage. Many builds use 50-80% of contingency; rarely 0% and rarely all of it.
Related Calculators
More Finance Calculators
Browse all finance →AI Cost Calculator
Compare token costs across OpenAI, Anthropic, and Google AI models. Calculate monthly API spending for GPT-4o, Claude, Gemini, and more.
Tip Calculator
Calculate the perfect tip and split the bill between friends. Choose preset percentages or enter a custom tip amount.
Bill Splitter Calculator
Split an uneven restaurant bill by item, divide tax and tip proportionally, and see exactly who owes whom.
Discount Calculator
Calculate sale price, discount amount, stacked discounts, sales tax, and total savings for any markdown.
Gas Mileage Calculator
Calculate MPG or km/L, estimate trip fuel cost, and compare annual fuel expenses between two vehicles.
Sales Tax Calculator
Add sales tax to a price, reverse-calculate the pre-tax amount from a total, and estimate tax for multiple items on one receipt.
Keep exploring
Next steps in Finance
Previous calculator
Net Worth Calculator
Add up assets and liabilities to see your net worth, compare debt versus wealth, and benchmark your progress by age.
Next calculator
Nightly Rate Calculator
Price an STR nightly rate from target monthly revenue, occupancy, season, and minimum margin over operating cost.