How the number is built

1. The imagery

The map is Google satellite imagery. In most towns and suburbs that is aerial photography flown from a plane, sharp enough to see bed edges, pool coping and fence lines. It is a real slippy map: pan to the back of the lot, zoom to the bed, and the shape you drew stays pinned to the ground rather than the screen. If Google’s map cannot load, the tool falls back to Esri World Imagery.

For jobs you judge from the street — siding, painting the house, power washing, gutters, roofing and Christmas lights — a See the house button opens Google Street View aimed at the property, so you can count stories and check the trim.

Resolution varies by location. In built-up areas it is commonly around 15 cm per pixel; in rural areas it can be considerably coarser. The tool shows the current scale in inches per pixel in the corner of the map, because that number sets the floor on how precise any measurement can be.

Imagery is not live. It is flown periodically, and a given tile may be months or a few years old. If you built a deck last summer it may not be there yet.

2. The measurement

Points are held as latitude and longitude in your browser, not as pixels, and reprojected every time the map moves. The outline itself is never saved: a saved quote or a job request keeps the measurement, the job and the address. That is what lets you zoom in to place a corner accurately without the area drifting. Area is computed on the projected coordinates with a scale factor derived from the map's own bounds at your latitude.

We test this by tracing a shape, then zooming and panning: a 75,105 square foot lot stays 75,105 across a two-step zoom, and drifts by about one square foot in 75,000 across a pan. That is well inside the error introduced by where you put the corners.

Where it is wrong, specifically:

• Overhang. Trees, eaves and awnings hide what is under them. A bed under a maple is one you have to estimate.
• Lean. Away from the center of an aerial photo, tall objects lean outward. Roof edges on a two-story house can sit several feet off their true ground position.
• Slope. Every measurement is the flat footprint. A sloped yard has more surface than its footprint, and a pitched roof considerably more — which is why roof jobs ask for the pitch and apply a multiplier rather than pretending the footprint is the answer.
• Your own tracing. On a phone, at a normal zoom, a fingertip covers a foot or two of ground. The tool is only as good as the corners you tap, which is why it tells you to zoom in.

The honest summary: accurate enough to order material from, not a survey, and not a substitute for a tape on anything that has to fit.

3. The quantities

Area alone is rarely what you buy. Each job carries the conversion through to the unit the supplier sells in.

• Volume jobs run square feet × your depth → finished cubic yards → loose yards with that material's own compaction factor → tons, using a density per material. Crusher run is about 1.5 tons a yard and settles roughly a quarter; #57 washed is about 1.4 and barely settles. Concrete also returns an 80 lb bag count.
• Roofs apply a pitch multiplier to the footprint and report squares, where one square is 100 square feet — not one square foot, which is a costly thing to misread on a quote.
• Lumber is figured against lengths that are actually sold. A 31.5 ft run does not return "one 32 ft board", because no such board exists; it returns two 16s. The common maximum for 2×8, 2×10 and 2×12 is 20 ft, and the solver will not exceed it.
• Waste is added as a percentage you can see and change, not baked in silently.

4. The cost

The price is built the way a contractor builds one:

Crew hours come from a production rate per job type — how much of that work a crew gets through in an hour. Every one of those inputs is editable. A contractor enters their own rates once and every quote uses them; a homeowner sees regional averages instead.

The price data only ever uses what a contractor charges, never what they pay for material. That distinction is deliberate: cost data is commercially sensitive and would make this a dangerous thing to contribute to. Charged prices are what a customer would see anyway. A contractor can choose to save what they pay a supply yard so the tool shows their own margin, but that figure is private to them and never enters the dataset.

5. The price data

Regional figures come from contractors who choose to report a finished job. Nothing is scraped, bought or inferred. Four rules govern publication, and they exist so that contributing cannot be used against the people who contribute:

• Never by company. No one can look up what a named contractor charged.
• Aged 45 days. A submitted price waits at least 45 days before it enters a published average. Live pricing helps nobody but colluders.
• Three contributors minimum. No regional figure appears until at least three separate pros have reported it, with none dominating the number.
• Everyone sees the same numbers. Averages are public to homeowners and contractors alike. There is no private tier, not even for Pro subscribers.

Where the data stands today: the ranges begin as published reference figures and are labeled that way on the site. They become real contractor numbers as contributions arrive. We would rather say that plainly than present an empty database as an authority.

Outside the United States

The tool measures anywhere there is aerial imagery. Prices follow the country the property is in:

• Canada, the UK, the eurozone (including Ireland) and Australia have their own researched material prices, in local currency, taken from local suppliers and trade price guides in September 2026. They are labeled “Estimated regional average — not yet local data”, because that is what they are.
• Installed prices outside the US appear only once at least three local businesses have shared their own hourly rate, under the same rules as above: never by company, aged 45 days, no one business dominating. Until then you see material prices only.
• Every other country sees the US figures in US dollars, with a note saying so.
• No tax is included anywhere. Every price on the site is before sales tax, VAT or GST, because rates differ by country, province and product and change often.
• Currency conversion uses the European Central Bank’s daily reference rate, only when you choose a currency other than the property’s own. It is a guide, not a bank rate.
• Metric units are the default outside the US and a switch on the tool. The measuring underneath is the same; only the display changes.

6. What this is not

It is not a bid, not a survey, and not a substitute for someone standing on the property. Estimates are a planning guide. Check quantities before you order — the arithmetic is only as good as the lines you draw, and we are not responsible for overages or shortfalls.

Found something wrong here? Tell us. Corrections from people who price this work for a living are the only reason any of it improves.