Home & PropertyCalculators

New: HVAC, driveway, roof-truss and generator planners

Planning tools that use your own measurements, label figures and quotes, with the method shown.

• Mini-Split BTU Estimator

  Preliminary single-room cooling BTU/h estimate using the ENERGY STAR sizing chart and its published adjustments.

• Room-by-Room CFM Planner

  Per-room and total airflow from air changes per hour, or cooling supply CFM from sensible loads, with a printable schedule.

• Roof Truss Geometry Calculator

  Rise, roof angle, sloping lengths with overhang and a preliminary truss count from span, pitch and spacing.

• Asphalt Driveway Cost Planner

  Itemized asphalt installation or resurfacing budget from your own quoted price per square foot.

• Driveway Sealing Calculator

  Gallons and containers of sealer from your product's label coverage, coats and container size.

• Generator Wattage Planner

  Running load, starting-load scenarios and essential-only totals from your appliance nameplate watts.

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What HomeCalc USA provides

HomeCalc USA is a collection of single-purpose calculators for the numbers that come up when buying a home, owning one, or running a construction or renovation project. Each tool focuses on one question — a monthly payment, a tax bill, a cubic yardage, a paint quantity — rather than trying to be a single do-everything estimator. That keeps the inputs short and the assumptions visible, so you can see exactly what drives the result and change any of them.

• Instant results

  Everything runs in your browser and recalculates the moment you change a number.

• Your own assumptions

  Rates, tax rates, waste allowances and material densities are all editable, so you can test scenarios instead of accepting a default.

• Estimates, clearly labelled

  Each tool states what it assumes and where real-world figures commonly differ.

• No account needed

  Nothing to sign up for and no inputs stored on a server — open a calculator and use it.

How the calculators work

Every calculator on the site follows the same basic flow, whether it is estimating a mortgage payment or a load of gravel.

1. 1. Enter your information

   Type in the numbers specific to your situation — purchase price, income, room dimensions, or material type.

2. 2. Adjust the assumptions

   Change the interest rate, tax rate, waste allowance, density or other defaults to match your own quote or product.

3. 3. Calculate

   Results update instantly in your browser as you type — there is no submit button that sends data anywhere.

4. 4. Review the breakdown

   Look past the headline number at the breakdown underneath it, which shows how each input contributed to the result.

5. 5. Compare related tools

   Follow the related calculators on each page to check the next question — for example, a payment estimate followed by a closing cost estimate.

Estimates vs. actual costs

Choosing the right calculator

If you are not sure which tool answers your question, start here.

Popular guides

Explanations of the formulas and rules of thumb behind the calculators.

• How Mortgage Payments Are Calculated

  The amortization formula behind a fixed-rate mortgage payment, a worked example, what PITI includes, and why your lender quote differs from a calculator.

• How Much House Can You Afford?

  How lenders calculate affordability using debt-to-income ratios, a worked example, and why the maximum you qualify for and the amount you should spend are different numbers.

• How Mortgage Refinancing Works

  How a refinance replaces your loan, the break-even math on closing costs, cash-out refinancing, and when refinancing usually does not pay off.

• How Much Gravel Do I Need?

  Convert length, width and depth into cubic yards and tons of gravel, choose a realistic depth, and understand why tonnage varies by product.

• How Much Concrete Do I Need?

  Calculate concrete for slabs, footings and post holes in cubic yards, with two worked examples, mix strength guidance and ready-mix ordering tips.

• How Much Flooring Do I Need?

  Measure rooms correctly, choose a waste percentage that matches your layout, and convert square footage into boxes with two worked examples.

From the blog

Deep material and cost guides — gravel, mulch, paint, roofing, property tax and closing costs — with US formulas, worked examples and the matching calculator.

• Gravel & aggregate

  How Much Gravel Do I Need for a Driveway?

  Depth, stone size and compaction decide how much gravel a driveway swallows. Here is the arithmetic suppliers use, in cubic yards and tons.

• Mulch & landscaping

  How Much Mulch Do I Need for Your Garden Beds?

  Bags or bulk? Two inches or four? The math behind mulch quantity, plus the depth rules that keep plants healthy instead of smothered.

• Paint & interior finishes

  How Much Paint Do I Need to Paint a Room?

  One gallon covers about 350 square feet per coat. Everything else is measuring walls properly and being honest about how many coats you need.

• Roofing & exteriors

  How Many Shingles Do I Need for a Roof?

  Roofers count in squares, not square feet. Here is how footprint, pitch multiplier and waste turn into the number of bundles on your driveway.

• Gravel & aggregate

  How Much Gravel Do You Need for a Walkway?

  A walkway is not a driveway — less depth, finer stone, and edging matter more. Here is how to size it in cubic yards and tons.

• Gravel & aggregate

  How Much Gravel Do You Need Under a Patio?

  A paver patio is only as good as its base. Here is how deep the crushed-stone layer should be and how to calculate the order.

Frequently asked questions

Are these calculators free to use?

Yes. Every calculator on HomeCalc USA is free and does not require an account, sign-up, or payment.

How accurate are the results?

Results are estimates produced from the numbers and assumptions you enter. Actual lender offers, tax bills, contractor quotes and material quantities can differ, so treat the output as a planning figure rather than a final number.

Do the calculations run in my browser?

Yes. Calculations run entirely in your browser, update as you change inputs, and the values you type are not stored on a server.

Can I change the assumptions behind a calculation?

Every calculator exposes its inputs, such as interest rate, tax rate, waste allowance or material density, so you can adjust them to match your own situation and compare scenarios.

Which calculator should I start with when buying a home?

Start with the home affordability calculator to set a realistic price range, then use the mortgage calculator to see the monthly payment at that price, and the closing cost calculator to see the cash you would need upfront.

Why do two calculators on this site give different numbers for the same house?

Each calculator answers a different question with different inputs — the mortgage calculator estimates a monthly payment from a rate and term, while the affordability calculator works backward from your income and debts. Small differences in the assumptions you enter, such as tax rate or insurance cost, also change the result.

Find the right calculator for your project.

22 calculators covering financing, property costs and materials.