Methodology

General estimating principles

Every vertical works the same way underneath. Five ideas hold across solar, pools, fences, driveways, siding, and HVAC:

1. One pure engine, no drift. Each estimate is produced by a pure calculation — your inputs plus our local data go in, a result comes out, with no hidden lookups. The same engine powers the calculator, the cost-by-state reports, and the numbers quoted in our guides, so they can never disagree.
2. A range, not false precision.We publish a low– high band rather than one fake-precise figure. Real bids vary by contractor, season, and site, and a range is the honest shape of the answer.
3. Local data × a labor multiplier.Prices are built from per-vertical material and rate data, then scaled by your state’s installed-labor multiplier — the single biggest reason the same project costs more in California than in Georgia.
4. A small-job premium.Small projects price higher per unit, because a crew’s fixed mobilization and minimums spread over less work.
5. The math is shown.Every cost page itemizes the breakdown — the material takeoff, each cost line, and the assumptions — and these are pre-qualification ballparks for planning, not quotes.

Solar methodology

We start from how much electricity you use, then work forward to system size, production, price, incentives, and payback. There are two paths — a quick estimate from your bill (Tier 1) and a satellite roof analysis via the Google Solar API (Tier 2) — but they only differ in how system size and yearly production are derived. From there both share one chain, so the tax logic stays consistent.

1. Annual usage.If you give kilowatt-hours we use them directly; if you give a monthly bill we divide by your state’s electricity price and annualize.
2. System size. We size the array to cover your target share of usage given local peak sun hours and a performance ratio for real-world losses, then round to a whole number of panels.
3. Production.Tier 1 estimates yearly output from size and sun hours. Tier 2 uses the roof’s actual modeled output (orientation, pitch, and shade), converted from DC to AC delivery.
4. Gross price.System watts × your state’s installed $ per watt (adjusted for roof material), plus battery cost if selected, plus a fixed $2,500of soft costs — permits, interconnection, design, and inspection — that every install carries regardless of size. Because those don’t scale with the system, a smaller array has a higher effective $ per watt and pays back more slowly.
5. Incentives (the 25D reality). For cash and loan buyers the federal residential credit is $0— Section 25D expired on 2025-12-31. We then subtract any state incentive to get net cost. A loan carries that net cost at 6.5% APR over 12 years. Lease/PPA customers pay $0 upfront; the installer claims the commercial credit (Section 48) and passes it through as a lower indicative monthly payment.
6. Savings, payback, and lifetime.Each year’s savings reflect panel degradation, electricity-price escalation, and your net-metering factor. Payback is the year cumulative savings cover net cost; lifetime savings sum the horizon and subtract net cost.

Estimate for pre-qualification, not a final engineering design.

Pool methodology

Pool cost does not scale cleanly like solar, so the model is additive: a base shell plus features. Tier 1 uses length × width from the form; Tier 2 uses the area and perimeter of a polygon you draw on a satellite map. Both feed the same chain.

1. Surface area.Length × width, or the measured area of your drawn shape.
2. Base shell.A fixed base for your pool type (gunite, fiberglass, or vinyl) plus area × the per-square-foot rate, adjusted by a regional labor multiplier and a depth factor.
3. Sitework. The shell is scaled by an excavation multiplier for flat, sloped, difficult-access, or rocky ground.
4. Features. Heating, decking, saltwater, automation, lighting, a spa, water features, a cover, and fencing are each added from published price ranges.
5. Total as a range. We present the total as a low/high band, because real bids vary by contractor and season.

Estimate for pre-qualification, not a quote; price varies by contractor, location, and season.

Fence methodology

A fence’s cost is dominated by its length and the installed rate for the material at your chosen height — roughly half of which is labor, which is why the site conditions move the total.

1. Fence run.Linear feet × the installed $/linear-foot rate for the material (wood, vinyl, chain-link, aluminum, or composite) at your height (4, 6, or 8 ft).
2. Site multipliers.Terrain (a gentle slope adds ~10%, a steep yard ~30%) and soil (rocky ground ~20%) scale the run — harder, slower digging.
3. Posts & concrete. Post count comes from material-specific spacing plus a post at each corner and gate; hole depth follows your local frost line, so colder states use more concrete per post.
4. Gates. Walk, double, and driveway gates are priced per opening, on top of the per-foot run.
5. Extras & region.Old-fence removal ($/lf) and a permit allowance are added as their own lines, and the whole run is scaled by your state’s installed-labor multiplier. Runs under the small-project threshold price higher per foot.

Ballpark estimate for planning, not a bid. Post counts assume a rectangular run; a contractor will confirm corners, gates, and local code. Get 3 local quotes before signing.

Driveway methodology

A driveway’s cost is mostly its square footage times an installed per-square-foot rate that swings with material. We price all four materials from the same inputs so you can compare.

1. Base.Area (sq ft) × the installed $/sq ft for the material (asphalt, concrete, pavers, or gravel) — surface, a standard base, and labor.
2. Depth scales material, not labor. The rate assumes a standard section; a thicker slab or lift scales only the material share (concrete by the cubic yard, asphalt by the ton).
3. Multipliers.Slope/drainage, what parks on it (cars vs. heavier), site access, and your state’s installed-labor multiplier each adjust the subtotal.
4. Extras. Tear-out and disposal of the old surface ($/sq ft) and a permit allowance are added as their own lines.
5. Material takeoff. Concrete cubic yards, asphalt tons, paver count, and base stone are shown so you can sanity-check a bid; small pads carry a per-foot premium.

Ballpark estimate for planning, not a bid. Assumes a rectangular pad on a standard base; soft soils, drainage work, and curb-cut/apron rules are the usual extras. Get 3 local quotes before signing.

Siding methodology

Re-siding is priced from wall area, which we estimate from your house footprint rather than a wall-by-wall measurement — so treat it as a planning range, not a takeoff.

1. Wall area.Footprint perimeter × grade-to-eave wall height, plus estimated gable triangles for the roof style, minus a share of the window, door, and garage openings (you choose how much to subtract).
2. Squares & waste.Net area is converted to siding squares (1 square = 100 sq ft) with a waste factor for cuts and overlaps — you pay for the order area, not the net wall.
3. Rate.Squares × the installed $/sq ft for the material (vinyl, fiber cement, engineered wood, or wood).
4. Multipliers.Story count (staging and lifts), how cut-up the house is, and your state’s installed-labor multiplier each adjust the subtotal; small jobs carry a premium.
5. Extras. Tear-off and disposal ($/sq ft) and a permit allowance are added as their own lines; starter strip, housewrap, and corner posts are counted in the takeoff.

Ballpark estimate for planning, not a bid. Wall area is estimated from your footprint — a contractor will measure each wall. Excludes hidden rot, sheathing replacement, and structural repairs found at tear-off. Get 3 local quotes before signing.

HVAC methodology

HVAC sizing works differently from the other verticals: it starts from two building loads, cooling and heating, rather than one footprint number, because summer and winter demand rarely match. Both loads scale with your square footage, climate zone, and the home’s envelope — this is a Manual-J-style screening calculation, not the real thing.

1. Cooling & heating loads.Square footage × a climate-zone BTU factor sets each load’s baseline — 20 to 30 BTU per sq ft for cooling and 25 to 50 BTU per sq ft for heating, depending on climate zone (a freeze-thaw climate needs the least cooling and the most heating; a hot-sun climate is the reverse).
2. Envelope multipliers.Both loads are then scaled by insulation quality (0.85–1.15), home age as an envelope-tightness proxy (0.93–1.10), and window area (0.95–1.10); ceiling height above the standard 8 ft basis adds load up to a 1.25× cap. Sun exposure (0.94–1.08) applies to the cooling load only.
3. Equipment sized to the nearest SKU. The cooling load converts to tons and snaps to the nearest residential unit size (1.5 to 5 tons) rather than rounding up — an oversized system short-cycles and dehumidifies poorly. Homes whose load runs meaningfully past a single 5-ton unit (roughly 5.5 tons and up) price as multiple separate systems. Furnaces are sized by output, not input: we pick the smallest input size (40 to 120k BTU) whose input × AFUE (80% standard, 96% high/premium efficiency) covers the heating load, and each system in a multi-unit home gets its own furnace sized to its share of the load. Mini-splits price per zone, at roughly 600 sq ft of conditioned space per zone.
4. Line items × your state.Equipment (AC, heat pump, furnace, or mini-split), ductwork (repair, replacement, or all-new), an electrical panel upgrade, and old-system removal are each priced from their own published range, plus a mechanical permit allowance — and the whole total is then scaled by your state’s installed-labor multiplier.
5. Not a Manual J.This is a screening calculation, not an ACCA Manual J load calculation — a licensed contractor must run the real thing, room by room, before install. It also excludes gas-line work, flue relining, asbestos abatement, and structural chases or returns for new ductwork.

Ballpark estimate for planning, not a bid. Sizing is a screening calculation from your square footage and climate — a contractor must run an ACCA Manual J load calculation before install. Excludes gas-line work, flue relining, asbestos abatement, and structural chases for new ducts. Get 3 local quotes before signing.

Live energy prices

Every dollar figure that depends on an electricity or gas rate — solar payback, pool heater and pump operating cost, HVAC seasonal energy cost — pulls that rate from the U.S. EIA API v2, not a static table we hand-update. We average EIA’s trailing 12 months of monthly state-level retail prices, so one unusually cheap or expensive month can’t skew a household’s estimate, and a script refreshes every state’s numbers monthly as EIA publishes new data. Every surface that uses a price — calculators, cost pages, and the energy-prices report — shows the exact window it’s averaging, a visible “through 2026-04” label, so you can judge how current the number is without digging into this page. That is provenance, not a precision guarantee: knowing where a rate came from and how fresh it is doesn’t turn a ballpark into a bid. Your actual utility rate depends on your provider, rate plan, and time of use, so treat these prices like every other number here — a screening estimate to sanity-check a real bill against, not a replacement for it.

Data freshness & update cadence

We cite primary sources, not other blogs, and each vertical carries its own. Pricing, rates, and incentives are reviewed on a quarterlyschedule, and immediately whenever a policy change (such as the 25D expiration) materially affects the math. Every calculator, cost page, and report shows a “last updated” date so you can judge freshness at a glance.

Full per-source detail lives on the data sources page.

Known limitations

An honest tool is clear about what it can’t do. Across every vertical:

• It’s a range, not a bid.Use it to plan and to sanity-check quotes — then get three local bids before signing.
• Site-specific extras are excluded. Hidden rot and sheathing under siding, bedrock and a high water table under a pool or driveway, soft soils and drainage, retaining walls, and curb-cut or apron work in the public right-of-way are the classic change orders a contractor prices on a walkthrough.
• Areas are estimated, not surveyed. Fence post counts assume a rectangular run; siding wall area is derived from your footprint; driveway and pool footprints come from your dimensions or a traced outline. A contractor measures the real thing. The Tier-2 satellite tools (roof analysis, draw-on-map) measure more precisely but are still estimates.
• Regional coverage varies. State-level pages and multipliers exist only where we have a complete data entry for that vertical; elsewhere we fall back to national-average pricing.
• Cost and sizing only.These tools produce data and math — not tax, legal, financial, or insurance advice. Solar tax/finance figures summarize public IRS guidance for planning; check a tax professional for filing eligibility.