Part 107 maximum altitude
Your maximum altitude under 14 CFR 107.51: 400 ft above ground, or up to 400 ft above a structure when you stay within 400 ft of it, shown above ground, above sea level, and above the ellipsoid.
Planning and education aid. Not for primary navigation. Full disclaimer
You may fly up to 700 ft above the ground here. Not legal advice.
- Why
- Notice
Provenance
- Computed by
- drone.ops.part107-altitude 1.0.0, core 0.1.0
- Model
- 14 CFR 107.51(b): 400 ft AGL, unless within a 400 ft radius of a structure and no higher than 400 ft above its immediate uppermost limit
- Accuracy
- Arithmetic on the rule and your inputs. MSL and HAE limits are only as good as the ground elevation and geoid height you enter.
- Notes
- None
- Cites
- Federal Aviation Administration, 14 CFR Part 107, Small Unmanned Aircraft Systems
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: 14 CFR 107.51(b): 400 ft AGL, unless within a 400 ft radius of a structure and no higher than 400 ft above its immediate uppermost limit
Show your work
The rule
14 CFR 107.51(b): 400 ft above the ground14 CFR 107.51(b)= 400 ftWithin the structure's radius
max = structure height + 400 ft300 ft + 400 ft, at 200 ft from it= 700 ft
The same steps an agent gets from the MCP server with explain: true.
Accuracy: Arithmetic on the rule and your inputs. MSL and HAE limits are only as good as the ground elevation and geoid height you enter.
When to use this: Use this when you fly under Part 107 and want the highest altitude you may reach: 400 ft above the ground in open country, or up to 400 ft above the top of a tower, building, or other structure while you stay within 400 ft of it sideways. Add the ground elevation to get the ceiling above sea level, and the geoid height for the ellipsoid height a GPS autopilot may use.
Limitations: This is the altitude limit of 14 CFR 107.51(b) only. It does not grant airspace access: in Class B, C, D, or surface Class E airspace you still need an FAA authorization, and a waiver, TFR, or local restriction can set a lower or higher limit. Structure height is measured from the ground at its base, so on sloping ground the height above the ground under the drone can differ. The sea-level and ellipsoid figures add your ground elevation and geoid height as entered; a geoid height without a ground elevation is not used. It does not cover recreational flying under 49 U.S.C. 44809. Not legal advice.
Worked example: 200 ft from a 300 ft tower. Source: add-drone-suite altitude scenario: 700 ft AGL (300 + 400). It is golden test vector v002, and every build checks the tool still gives its answer within its tolerance.
You enter
- Distance from the structure
- 200 ft
- Structure height
- 300 ft
You get
- Maximum altitude above ground
- 700 ft
- Why
- Within 400 ft of the structure, you may fly up to 400 ft above its top (300 ft), per 14 CFR 107.51(b). Beyond 400 ft from it the limit drops back to 400 ft above the ground.
- Notice
- Summary of rules as of 2026-09-18. Not legal advice. Check the current regulation and any waivers, authorizations, or local restrictions: https://www.ecfr.gov/current/title-14/chapter-I/subchapter-F/part-107/subpart-B/section-107.51
Review: Not yet independently reviewed by a Part 107 remote pilot.
Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Checked against: 22 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- 14 CFR Part 107, Small Unmanned Aircraft Systems, Federal Aviation Administration, eCFR, current text (dated on the page as "Rules as of"). §107.51 (operating limitations) and §107.120 (operations over people, category 2). Rules as of 2026-09-18.
Terms
- MSL: mean sea level
- Height above the average level of the sea, in practice the geoid. Airport elevations and altimeter altitudes are given above MSL. Source: Aeronautical Information Manual
Learn the concept: How far can you see a drone? VLOS explained, What is ground sample distance (GSD)?, What is the Part 107 altitude limit?