Short answer
Formula: construction cost = size x base cost x location x finish x complexity. Total estimate = construction + soft costs + contingency.
Guide
What to check before the expensive part.
Use a formula, then challenge it
The formula creates the first range. The real work is checking whether the assumptions match the property.
Soft costs belong in the estimate
Design, drawings, engineering, permits, plan check, energy compliance, and utility review are not extras.
Contingency is not padding
It is the budget for unknown conditions, incomplete scope, and market movement.
Budget notes
Numbers worth separating.
| Item | Range | Why it matters |
|---|---|---|
| Base cost | Project-specific | ADU, addition, remodel, kitchen, bath, and custom homes behave differently. |
| Location | 1.0x-1.95x | National, California, Bay Area, and high-cost city multipliers. |
| Contingency | 10%-20% | Higher when complexity is unknown. |
Calculator
Put numbers against the idea.
Live calculator
Check a planning range
Value first. No email wall, no fake exact quote.
Want a human to sanity-check the range?
Optional. The estimate already did its job. Send it only if you want a Bay Area planning review.
FAQ
Quick answers.
Is this a contractor bid?
No. It is a planning estimate that helps you understand the likely budget range before drawings, engineering, city review, and contractor pricing.
Why is the range wide?
Early construction budgets should be ranges because site conditions, structural scope, utility work, finishes, permits, and contractor availability can move the number fast.
Do I need to enter contact information?
No. The estimate appears first. Contact information is only for saving the estimate or asking for a local review.