Project Contingency Calculator

Safe budget = base × (1 + contingency %). New construction 5%, remodels 10-15%, gut renos 20%+.

Inputs

Result

Loading calculator…
—

General calculation reads

Amazon affiliate
How Not to Be Wrong
Jordan Ellenberg - math thinking
Shop on Amazon
The Joy of X
Steven Strogatz - accessible math
Shop on Amazon
Scientific calculator (Casio fx-991EX)
Shop on Amazon

As an Amazon Associate we may earn from qualifying purchases. This does not add cost for you.

How to use this calculator

  • Enter your base estimate from quotes.
  • Pick project type — be honest about complexity.
  • Don't share contingency budget with contractors.
  • Treat contingency as held aside, not spendable.

About this calculator

Contingency is what stops a project from becoming a personal-finance crisis. Industry rules of thumb: 5% for new construction (everything is unbuilt and visible), 10-15% for remodels (kitchens, baths reveal hidden problems), 20-25% for full gut renos, 30%+ for historic restorations and structures over 75 years old. Contingency lives in your budget, not the contractor's — they don't see it. If you tell the contractor your max is $80k and you have $70k base + $10k contingency, the bid will eat the contingency.

Frequently asked

Why higher % for older homes?+
Pre-1980 homes: lead paint, asbestos, knob-and-tube wiring, undersized supply lines, lath-and-plaster walls. Each can add $5-15k unexpectedly.
What if I don't use it?+
You're ahead. Don't reallocate to upgrades until project is 90% complete — surprises cluster late.
Different from change order budget?+
Change orders = scope changes you decide on. Contingency = unforeseen conditions. Some teams combine; cleaner to track separately.
Should the contractor know?+
No. Quote them on base scope. If you reveal contingency, expect it to be eaten by "discovered" conditions.
When can I release it?+
After substantial completion when no surprises remain. Many homeowners hold it until punch list is done — that's wise.

Related calculators

Change Order Cost Impact Calculator
Revised total = base contract + change orders + contingency. Track scope creep against budget.
Contractor Markup Calculator
Invoice = (material + labor) × (1 + markup %). Standard residential markup is 15-25%; remodeling 20-30%.
Kitchen Remodel Cost Calculator
Kitchen remodel cost = sq ft × $/ft² (basic / mid-range / luxury) + appliance package.
Bathroom Remodel Cost Calculator
Bathroom remodel cost = sq ft × $/ft² (basic / mid / luxury) + fixture package.
Project Cash Flow Calculator
Monthly cash flow = inflows (loan draws, owner contributions) − outflows (labor, materials) over project duration.
ROI on Renovation Calculator
ROI = (post-value − pre-value − reno cost) / reno cost. Factor in regional appreciation to separate true ROI from market gains.

More tools you might like

Hand-picked tools that pair well with this one — same audience, same intent.

Change Order Cost Impact Calculator
Calc

Revised total = base contract + change orders + contingency. Track scope creep against budget.

Project Cash Flow Calculator
Calc

Monthly cash flow = inflows (loan draws, owner contributions) − outflows (labor, materials) over project duration.

ROI on Renovation Calculator
Calc

ROI = (post-value − pre-value − reno cost) / reno cost. Factor in regional appreciation to separate true ROI from market gains.

Kitchen Remodel Cost Calculator
Calc

Kitchen remodel cost = sq ft × $/ft² (basic / mid-range / luxury) + appliance package.

Bathroom Remodel Cost Calculator
Calc

Bathroom remodel cost = sq ft × $/ft² (basic / mid / luxury) + fixture package.

Project Charter Template (Kickoff)
Docs

A project charter for kickoff — purpose/objectives, in-scope and out-of-scope, stakeholders, milestones/timeline, budget, and success criteria — to authorize the project and align everyone before work starts.