Comparisons & Guides · For yards, quarries & crews

Drone vs Phone for Stockpile Measurement: Cost, Part 107, Airspace and When Each Wins

October 24, 2026 · 8 min read

A drone and a phone build a stockpile model the same way, from overlapping photos. They differ in where the camera is, what it costs to put it there, where the law lets it go and how long the job takes. Here is how to choose, and why most sites end up using both.

In short

Both are photogrammetry. A drone sees every pile’s top from above; a phone sees the toe and faces from the ground. Published drone tests land within a few percent of laser surveys; a state DOT found a phone app within about 1.5–2%.
A drone program costs a drone, a Part 107 certificate (about $180–330 to get, free to renew), insurance, mapping software and processing time. A phone app costs $0–20 a month and needs no license.
A drone cannot fly under a roof, needs airspace authorization near airports and cannot fly over people without waivers. A phone cannot see the top of a very tall pile or circle a pile against a wall.
One pile, a delivery or an indoor shed: phone. Thirty piles across a site: drone. Most yards do a drone or survey quarterly and phone scans monthly.

Same math, different camera

Structure-from-motion software finds the same features in overlapping photos, works out where the camera was for each, and triangulates a dense cloud of points on the pile’s surface. A drone takes those photos in a grid from a hundred feet up; a phone takes them while you walk the toe. Scale and position come from ground control points or an RTK receiver on the drone, and from LiDAR or motion tracking on the phone. The photogrammetry vs LiDAR explainer covers what each sensor contributes; this article is about everything around the camera.

Accuracy: what the evidence says

Drones have the larger literature. A 2020 study from the Estonian University of Life Sciences benchmarked drone photogrammetry against terrestrial laser scanning and found every photogrammetric model within 4% of the laser-scanned volume, even without ground control points. Propeller, which sells drone surveying, puts its volumes within 97–99% of true with high-precision ground control and warns that without it a drone map can drift by tens of centimeters. Phones have one well-documented test: the Texas Department of Transportation, reported by ENR, found a phone video app within about 1.5% of LiDAR and GPS surveys on piles under 100 cubic yards, with the vendor claiming 2% on larger ones.

The geometry explains the one real difference. A drone photographs the top of every pile, so a flat-topped 40-foot stockpile is fully captured; a person at its toe cannot see the top, so the phone has to infer it. On piles a few yards high, which is most yard inventory, the two see the same thing. On both, the base surface under the pile and the density you convert with usually matter more than the scanner, as how accurate a stockpile measurement really is explains. Stockpile Scan reports a ± range for each scan rather than a blanket percentage for that reason.

What each one costs

Item	Drone program	Phone app
Hardware	Mapping drone, $1,000 to $10,000 or more; RTK or ground control points extra	The iPhone already in your pocket
Licensing	Part 107 knowledge test $175, drone registration $5; $180 self-taught or about $330 with a prep course; free online renewal every 24 months	None
Insurance	Aviation liability, about $1,200 a year in one small operator’s published breakdown	None beyond normal business cover
Software	Mapping and processing subscriptions, commonly a few hundred dollars a month	$0 (Stockpile Scan) to about $20 a month (SR Measure Professional)
Processing	Upload and cloud processing, from half an hour to hours per flight	On the phone, minutes per pile
People	A certificated pilot on staff or under contract	Anyone who can walk around the pile

Costs are US figures from the sources listed below and vary by vendor and region. The Part 107 figures are from Pilot Institute’s cost guide.

The licensing line is smaller than people expect: Pilot Institute’s cost guide puts the certificate at about $300 for most people, and renewal is a free online course. The recurring lines add up: software, insurance and the pilot’s time. A yard with two piles never amortizes them; a quarry with fifty does.

Time per pile, time per site

A drone flight over a 20-acre yard takes about twenty minutes and captures every pile at once; processing runs while you do something else. A phone scan takes three to five minutes per pile, and the volume is ready before you reach the next one. For thirty piles that is a two-hour walk against a twenty-minute flight plus processing, and the drone wins. For one pile, or the three that moved this week, the phone is done before the drone is out of its case.

Where a drone cannot go

The FAA’s Part 107 rules shape where and when a drone survey can happen. In controlled airspace near an airport the pilot needs an authorization, usually through LAANC, which is quick for low altitudes but not guaranteed. Flying over people or moving vehicles is restricted by drone category, which matters on a working yard with trucks in the lanes. Night flights need anti-collision lighting and training, the pilot must keep the aircraft in sight, and wind and rain ground it.

Then there are roofs. Mapping drones position themselves with GPS and mapping software assumes it, so a salt shed, a dome or a covered bay is effectively closed to them. Those piles are measured from the ground, by laser scanner or by phone, which is why the road salt inventory guide never mentions a drone.

Where a phone struggles

The phone’s limits are the mirror image. A pile much taller than about 15–20 feet hides its own top from someone standing at the toe, so the model has to fill it in, and the ± range grows. A pile against a wall or bunker face cannot be fully circled, so part of its surface is never seen; apps handle this with a reference surface or a straight border, at some cost in certainty. A very large pile is a long walk, loaders working mid-scan change the answer, and heavy vegetation confuses any camera.

People, data and process

A drone program needs a certificated pilot available when the weather is right, in practice a trained staff member or a contractor on a schedule. A phone program needs whoever is already in the yard. Data flows differ too: drone photos go to a cloud service for processing, while phone apps split between cloud and on-device processing; Stockpile Scan builds the model on the phone and never uploads the photos. Both can deliver the records an auditor wants, a dated report with photos, the border used and the density assumed, and the reconciliation guide covers what to keep.

When each wins

Drone: a site with dozens of piles, piles too tall to see over, a site survey that also needs pit faces and haul roads, and a staff pilot who flies regularly.
Phone: one pile or a handful, a delivery to check before the truck leaves, anything under a roof, controlled airspace, a yard with trucks moving, and any operation without a licensed pilot.
Both: the common answer. A drone or survey measures the whole site quarterly or at year end, and phone scans cover the monthly counts and the piles that moved. The quarterly number anchors the books; the monthly ones catch the drift before it becomes a write-off.

Part 107 in two paragraphs

Any drone flight for a business in the United States, including measuring your own piles, falls under Part 107. The pilot holds a Remote Pilot Certificate: at least 16 years old, a passed Unmanned Aircraft General knowledge test at an FAA-approved center, and the drone registered with the FAA. The FAA’s step-by-step guide covers the process; the recreational TRUST certificate does not count for work.

Operating rules follow the certificate: keep the aircraft within visual line of sight, stay at or below 400 feet above the ground, get authorization in controlled airspace, meet the lighting and training requirements at night, and respect the categories for flying over people. Every 24 months the pilot completes free online recurrent training to keep the knowledge current. None of it is hard, but all of it is overhead a walk around the pile does not carry, which is the whole trade.

Frequently asked questions

Do I need a Part 107 license to measure stockpiles with a drone?

In the United States, yes. Measuring piles for a business is a commercial operation, so the pilot needs an FAA Remote Pilot Certificate under Part 107: be at least 16, pass the aeronautical knowledge test at an FAA-approved testing center, register the drone, and complete free online recurrent training every 24 months. The recreational TRUST certificate does not cover work flights.

How much does a drone stockpile survey cost?

Running your own program means a mapping drone at $1,000 to $10,000 or more, a Part 107 certificate at roughly $180 to $330 including the $175 knowledge test, insurance that one small operator puts at about $1,200 a year, mapping software commonly a few hundred dollars a month, and staff time to fly and process. Contracted surveys are quoted per visit and vary with site size and region. A phone app costs $0 to about $20 a month and needs none of the rest.

Can a phone replace a drone for stockpile measurement?

For a single pile, a delivery check, an indoor pile or monthly counts at a small yard, yes: a walk-around phone scan gives a volume in minutes with no license. For a large site with dozens of piles, or piles too tall to see the top of from the ground, a drone is faster and more complete. Many operations use a drone or survey for the whole site a few times a year and a phone in between.

Can you measure an indoor stockpile with a drone?

Not usefully. Mapping drones rely on GPS for positioning and most mapping software assumes it, so under a roof you are flying manually in a confined space with a degraded model. Salt sheds, domes and covered bays are where ground-level methods win: a phone scan or a terrestrial scanner, both of which work without GPS.

The phone half of the plan is free

Stockpile Scan is free, with no ads, subscriptions or account. Walk around a pile and get its volume, a ± range, a weight estimate and a PDF report, with no pilot certificate and no airspace to clear.

Download on the App Store

Any iPhone with iOS 18 or later. LiDAR optional. Learn more about the app.