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Sitework Overrun Calculator

Sitework overruns blow budgets. This calculator sizes typical overrun probability.

Sitework budget

Soil risk %

Utility conflict %

Weather risk %

Contingency held %

Net overrun exposure

$280,000

Total risk %

25.00%

Contingency held

$420,000

How the math works

Total risk = sum of risks. Net exposure = risk dollars − contingency.

Before committing to a sitework budget, invest $15-40k in geotechnical, environmental, and utility survey work. That pre-investment typically reveals the 60-80% of discovered conditions that become change orders — much cheaper to design around than to blast through.

Editorial noteMaintained by EveryCalc - Reviewed June 2026

EveryCalc calculators are designed for fast, practical estimates with transparent inputs and no required account. We use plain formulas, visible assumptions, and related tools so visitors can check the result from more than one angle.

Results are informational only. For financial, tax, legal, medical, construction, or other high-impact decisions, verify the output against primary sources or a qualified professional.

Learn more about our review process on the EveryCalc methodology page.

How this calculator works

What this page estimates

This Sitework Overrun Calculator is built to give a quick, browser-based estimate for sitework overrun. Sitework overruns blow budgets. This calculator sizes typical overrun probability. The inputs stay on the page during normal use, and the result should be treated as an estimate for planning, comparison, or education rather than professional advice.

Calculation approach

The calculator applies the standard relationship implied by the inputs, then formats the answer so it can be checked and reused. For finance tools, the most important step is using consistent units, rates, time periods, and assumptions before comparing the result with another calculator or outside quote.

Example workflow

For example, start with a realistic value you already know, change one input at a time, and watch how the answer moves. That makes it easier to tell whether the result is being driven by the main amount, the rate, the time period, or a unit conversion.

Practical checks

Use current, real-world numbers when the result affects money, health, tax, or legal decisions.
Run a low, base, and high case when the inputs are estimates.
Check the related calculators below when the next decision depends on a different assumption.

How to interpret the sitework overrun result

Best use

Use the result as a planning number for comparing payments, rates, returns, tax reserves, or cash-flow choices before you request a quote or make a commitment.

Cross-check

Compare the answer with the contract, lender estimate, tax form, brokerage statement, payroll record, or invoice that will control the real-world outcome.

Watch for

Do not rely on a single optimistic rate, return, or fee assumption. Money pages work best when you run low, base, and high cases and keep professional advice separate from the estimate.

This page belongs to the Finance calculator library, so the answer should be read in the context of the decision you are modeling rather than as a universal rule.

Before relying on this sitework overrun estimate

Most calculator mistakes come from the inputs, not the arithmetic. Use this short audit before you reuse the answer in a spreadsheet, quote, application, or important conversation.

Confirm source numbers

Match balances, rates, fees, taxes, income, and payment dates against the lender quote, payroll record, tax form, statement, invoice, or contract.

Separate cash flow from total cost

A lower monthly payment can still cost more over time if fees, interest, taxes, or a longer term are hidden in the structure.

Run conservative cases

Test at least one higher-cost or lower-return case before using the output for a purchase, refinance, investment, loan, or tax decision.

Rerun this page when the rate, price, term, fee, tax rule, income, expense, or expected holding period changes.

How to Use

Enter sitework budget.
Enter unknown soil risk %.
Enter utility conflict risk %.
Enter weather delay risk %.
Enter contingency held %.
Read probability-weighted overrun.

Frequently Asked Questions

Typical overruns?

Clean sites (agricultural, greenfield): 5-15% overrun. Infill sites (urban, previously developed): 15-40%. Contaminated sites: 40-150%. Rocky or high-water-table sites: 20-60%. Soils report is the best early warning.

Hidden drivers?

Undocumented utility lines (cost to relocate + delay). Rock excavation (blast or hammer costs 5-10x regular). Groundwater (dewatering $5-50k/month). Archaeological findings (full site stop). Each is catastrophic when not identified.

Contingency?

15-25% sitework contingency is market standard. Complex sites: 25-40%. Brownfield/redevelopment: 40-60%. Under-contingent bids lose first to change orders, second to discovered conditions.

How often should I rerun this?

Rerun this calculator whenever inputs change materially — new rent roll data, rate moves, loan balance updates, or quarterly operating data. For active deals, monthly refresh is typical. For stabilized assets under monitoring, quarterly is fine. Treat the output as a decision tool, not a one-time answer — market conditions evolve and so should your analysis.