What the calculators are for
Every calculator on MyHomePlatform is a planning tool. It is meant to answer questions like "roughly what will this cost," "how much should I set aside," and "is the quote in front of me reasonable." It is not a quote, an appraisal, an insurance proposal, or tax advice, and it cannot see your house.
We hold the calculators to four rules.
- Show the assumptions. Every unit cost, percentage, and threshold a calculator uses is printed on its page, so you can check it against what you know about your own market.
- Show a range where prices vary. Project costs are given as low, typical, and high, never as a single figure.
- Show the formula. Each page states how the result is calculated, in a form you could reproduce on paper.
- Say what is left out. Each page ends with the costs and situations the estimate does not cover.
How a project cost estimate is built
The project cost calculators for kitchens, bathrooms, roofs, windows, additions, new construction, flooring, tile, painting, garage doors, tree removal, mold remediation, and heating and cooling share one structure.
1. Quantities
The estimate starts from a physical quantity: square feet of roof, linear feet of cabinets, tons of cooling capacity, or a count of fixtures. Where you are unlikely to know the quantity, the calculator derives it from something you do know, usually floor area, using a stated ratio. The roof calculator multiplies the building footprint by a pitch factor. The kitchen calculator assumes 0.17 linear feet of cabinets per square foot of floor. Whenever a measured figure can replace a derived one, the calculator lets you enter it.
2. Unit costs with three values
Each option carries an installed cost, per unit or as a flat amount, at three levels:
- Low: economy products, straightforward installation, a competitive bid.
- Typical: the midpoint we would use to set a budget.
- High: better products, harder access, or a busier market. It is not a ceiling.
"Installed" means materials plus the labor to put them in. Low, typical, and high totals are each the sum of the low, typical, and high lines. Because every line is unlikely to come in low or high at once, the ends of the range are wider than most real projects, and the typical figure is the one to plan around.
3. Scope adjustments
Conditions that make the same work cost more are applied as multipliers on the relevant lines: a steep or complex roof, a second story, a high-efficiency equipment tier. The multiplier and what it applies to are listed on each page.
4. Local cost level
You choose one of three levels:
| Level | Factor | Use it when |
|---|---|---|
| Lower-cost area | 0.9 | Rural areas and regions where labor rates run below the national average |
| National baseline | 1.0 | Most suburbs and mid-sized cities, or when you are unsure |
| High-cost metro | 1.2 | Large coastal metros and other markets with high labor rates |
The factor is applied to labor-driven lines. Items priced nationally, such as an appliance package, and permit fees are not adjusted. We do not use ZIP-code pricing. Local prices depend on which contractors are available and how busy they are, and a lookup table would suggest precision that the underlying data does not support.
5. Overhead and contingency
The remodel calculators add 10% to 20% for a general contractor's overhead and profit when you select that option, then apply the contingency percentage you choose to the whole amount. Contingency is a reserve for conditions discovered after work starts, not an extra charge.
Where the figures come from
- Project costs. Compiled from published remodeling and trade cost guides, manufacturer and supplier pricing guides, and Zonda's Cost vs. Value Report, which we use as a check on whole-project totals. Published sources often disagree, sometimes by a factor of two. Where they do, we set the range to span the credible figures.
- Resale value. National averages from the Cost vs. Value Report, cited by year wherever they appear.
- Tax rules and thresholds. IRS Publication 523, IRS tax topics and frequently asked questions, and the annual revenue procedure that sets inflation-adjusted amounts.
- Insurance. The coverage structure and special limits of the standard ISO homeowners forms, and published rate analyses for premium averages. Claim frequency and severity come from the Insurance Information Institute.
- Mortgage math. Standard amortization formulas and widely used lending guidelines such as the 28/36 rule.
- Equipment life and efficiency standards. Manufacturer guidance and U.S. Department of Energy minimum efficiency rules.
We do not have our own database of completed projects, and we do not present compiled ranges as measured averages. Where a number is a rule of thumb, such as a share of home value to spend on a kitchen, the page says so.
Each calculator at a glance
| Calculator | How the result is produced | Last reviewed |
|---|---|---|
| Kitchen Remodel Cost | Itemized. Cabinet, countertop, and backsplash quantities are derived from floor area, then multiplied by an installed unit cost for the option you choose. Contractor markup and contingency are applied to the total. | November 2026 |
| Bathroom Remodel Cost | Itemized. Fixtures are flat installed costs; flooring, wall tile, and paint scale with floor area. Contractor markup and contingency are applied to the total. | November 2026 |
| Roof Replacement Cost | Roof area is the footprint multiplied by a pitch factor. Installed cost per square foot depends on material and is adjusted for shape, height, and steep pitch. Tear-off, decking, and flashing are separate lines. | November 2026 |
| Home Addition Cost | Floor area multiplied by a construction cost per square foot for the addition type and finish level. Bathrooms, a kitchen, heating and cooling, design fees, permits, and contingency are added. | November 2026 |
| Cost to Build a House | Living area multiplied by a construction cost per square foot for the quality level, anchored to the NAHB Cost of Constructing a Home survey. Builder markup, plans, permits, site work, contingency, loan interest, and land are added. Uses a 1.25 factor for high-cost metros. | November 2026 |
| Window Replacement Cost | A per-window installed price by window type, multiplied by frame, glass, height, and local factors. Full-frame installation, opening repair, and lead-safe work are added per opening. | November 2026 |
| Hardwood Flooring Cost | Floor area, plus a waste allowance, multiplied by the wood price, and floor area multiplied by a labor rate and layout factor. Site finishing, removal, subfloor repair, baseboards, and stair treads are added. A separate mode prices sanding and refinishing. | November 2026 |
| Tile Installation Cost | Tile is priced on area plus waste. Labor is a base rate multiplied by material, location (floor, wall, shower), pattern, and local factors. Setting materials, removal, backer board, and waterproofing are added per square foot. | November 2026 |
| Interior Painting Cost | Wall area is estimated at 2.7 times floor area at an 8-foot ceiling and scaled for height. Walls are priced per square foot of wall, adjusted for condition and color change; ceilings and trim per square foot of floor; doors each. | November 2026 |
| Garage Door Replacement Cost | An installed price per single or double steel door, multiplied by material, insulation, wind-rating, and local factors. Openers, window sections, and removal are added per door. | November 2026 |
| Tree Removal Cost | A price per tree by height, multiplied by access, condition, emergency, and local factors. Stump grinding is added per stump and a permit as a flat amount. | November 2026 |
| Mold Remediation Cost | Affected area multiplied by a price per square foot for the location, subject to a minimum job charge. Rebuild is added per square foot; HVAC cleaning, testing, and moisture repair as flat amounts. | November 2026 |
| HVAC Replacement Cost | A fixed cost plus a cost per ton of capacity for each system type. Capacity is estimated from floor area and climate unless you enter it. Efficiency tier, ductwork, and electrical work are added. | November 2026 |
| Home Sale Proceeds | Arithmetic on your own inputs: sale price minus percentage costs, fixed costs, and loan payoffs. The starting percentages are placeholders, not market averages. | November 2026 |
| Capital Gains on Home Sale | Follows the gain worksheet in IRS Publication 523, the Section 121 exclusion, and the 2026 long-term capital gains thresholds from Revenue Procedure 2025-32, plus depreciation recapture, the net investment income tax, and a state rate you enter. | November 2026 |
| Home Insurance | Replacement cost is square footage multiplied by your rebuild cost per square foot. Other limits use the standard policy percentages of the dwelling limit. The 80% rule check uses the standard loss settlement formula. | November 2026 |
| Personal Property Coverage | A room-by-room total of your own replacement estimates, compared with your Coverage C limit and the special limits on the standard ISO HO-3 form. | See page |
| Renovation ROI | National average job cost and resale value for 28 projects from Zonda’s 2025 Cost vs. Value Report. | See page |
| Annual Maintenance Cost | A percentage of home value that rises with the age of the house, plus per-system allowances and a climate adjustment. | See page |
| Home Emergency Fund | A percentage of home value based on the age of the house, plus allowances for special features and a location adjustment. | See page |
| Home Affordability | The 28/36 debt-to-income guideline and a standard amortization formula, with allowances for property tax, insurance, and mortgage insurance. | See page |
| Mortgage Refinance | Standard amortization formulas applied to your current and proposed loans, with break-even and lifetime interest comparisons. | See page |
| Digital Home Record ROI | Claim frequency and average claim size from the Insurance Information Institute, combined with illustrative assumptions that you can change. | See page |
What the estimates leave out
Some costs are excluded from every project calculator because they cannot be estimated without seeing the house:
- Hidden damage: rot, mold, outdated wiring, failed plumbing, and structural problems.
- Hazardous materials: asbestos and lead paint testing and abatement.
- Structural engineering and work that changes the building's footprint.
- Design and architectural fees, sales tax, and financing costs.
- Rebates, tax credits, and insurance proceeds, which are never subtracted.
- The cost of living elsewhere or eating out while work is underway.
The tax and insurance calculators have their own limits. The capital gains calculator applies federal rules for one tax year and a flat state rate. The insurance calculator applies the standard form of each policy provision, which an individual policy may change. Those pages list what is not modeled.
Your data
All calculations run in your browser. We do not store the values you enter, and we do not share them with contractors, lenders, insurers, or advertisers. No sign-up is needed to see a result. We do not run a contractor marketplace and do not sell leads.
Like the rest of the site, calculator pages load the analytics tools described in our privacy policy, which measure how pages are used and can include session replay. On the calculators marked as reviewed in November 2026 in the table above, the calculator panel is masked from session replay, so the figures you enter and the results are not recorded.
Reviews and corrections
Cost assumptions are reviewed at least once a year. Tax thresholds are updated when the IRS publishes amounts for a new tax year, and tax and incentive rules are rechecked when legislation changes them. Each calculator page shows the month its figures were last reviewed, and the table above repeats those dates for the calculators maintained under this methodology.
If a figure looks wrong for your area, or you find an error in a formula, please tell us. Include the calculator, the inputs you used, and what you expected to see. We correct confirmed errors and update the review date on the page.
How to use an estimate well
- Run the calculator with your best inputs and note the typical figure and the range.
- Get at least three written, itemized quotes or professional opinions.
- If a quote falls outside the range, ask what it includes that the others do not. The answer is usually scope, not price.
- Set your budget from the quotes, with a contingency, and use the calculator's monthly set-aside figures to fund future replacements.
- Keep the contract, invoices, permits, and warranties. They support insurance claims, warranty claims, and your home's cost basis. A digital home record keeps them in one place.