housecostcalc

How we estimate

Every number on this site comes from a published source and a formula you can check. This page lists both, calculator by calculator. Prices were last reviewed in October 2026.

Our approach

  • We start from national price guides, manufacturer and trade data, and government sources such as the U.S. EPA and state building codes.
  • Where sources disagree, we use a range that covers the credible figures rather than a single average.
  • We adjust for the factors contractors actually price: size, materials, access, height and extra work.
  • Location: when you enter a ZIP code or city, the estimate is multiplied by your state's Regional Price Parity from the U.S. Bureau of Economic Analysis (2023 data, U.S. average = 100). For example, California is 112.6, Texas 97.2 and Arkansas 86.5. Without a location, results use the U.S. average. Source: BEA Regional Price Parities.
  • Results are rounded so they don't look more precise than they are.
  • We review prices at least twice a year and when a source publishes new data.

House repiping

  • Installed rate per sq ft of living space: PEX $2.70–$4.00, CPVC $4.50–$5.70, copper $6.50–$12.00. Labor is about 70% of the pipe work.
  • +8% per extra story; slab foundation +15%; unfinished basement −5%.
  • Each bathroom beyond two: +$600–$1,600. Drywall patching and paint: $1.60–$3.00 per sq ft. Permit and inspection: $100–$800.
  • Sources: HomeAdvisor, Tommy Cool.

Gutter installation

  • Installed gutters per linear ft: vinyl $4–$9, seamless aluminum $7–$16, galvanized steel $10–$22, zinc $15–$35, copper $28–$50.
  • Downspouts per ft: vinyl $5–$8, aluminum $9–$12, steel $10–$14, zinc $14–$22, copper $17–$30. Default: one downspout per 35 ft of gutter, about 10 ft per story plus 2 ft.
  • Each extra story: +$1–$3 per ft. Old gutter removal: $0.65–$0.85 per ft. Gutter guards: $7–$12 per ft. Job minimum about $500. Roof-area method: linear ft ≈ roof sq ft ÷ 10.
  • Sources: Bob Vila, Inch Calculator.

Mold remediation

  • $10–$25 per sq ft of affected area, minimum about $500–$1,000.
  • Location: bathroom and basement ×0.9, crawl space ×1.0, attic ×1.15, inside walls ×1.25. Severity: surface ×0.8, moderate ×1.0, heavy tear-out ×1.35. HVAC and ducts: $3,000–$10,000 as a separate job.
  • Repairs: drywall $1,000–$2,900, hard flooring $200–$550, carpet $775–$2,600.
  • Sources: SERVPRO, U.S. EPA.

Bathroom remodel

  • Midrange base cost: $8,400 + $107 per sq ft, ±13%, calibrated to published cost-by-size averages.
  • Finish level: basic refresh ×0.62 (±12%), midrange ×1.0, upscale ×1.88.
  • Moving plumbing or changing layout: +$2,500–$6,500. Freestanding tub: +$900–$1,800.
  • Source: This Old House (2026).

Septic tank size

  • Typical U.S. minimum: 0 bedrooms 750 gal; 1–3 bedrooms 1,000 gal; 4 bedrooms 1,250 gal; +250 gal per extra bedroom.
  • Stricter rule (New Hampshire Env-Wq 1010.01): 1,250 gal for up to 4 bedrooms, +250 gal per extra bedroom.
  • Garbage disposal: +50%. Result rounded up to the next standard tank size. Daily wastewater: 50–100 gal per person.
  • Sources: Angi, New Hampshire Env-Wq 1010.01, U.S. EPA.

What estimates don't include

Unless a calculator says otherwise, results don't include hidden damage found during the job, structural repairs, design fees, financing costs or taxes. Always get written quotes before you commit. See our disclaimer.

Spot an error?

If a price looks wrong for your area, email hello@housecostcalc.com with the calculator, your ZIP code and the quote you received. Real quotes help us keep ranges accurate.