Drone flight time

Model: Time = energy × usable share × (1 − derating) × (1 − reserve) / power; heuristic cold derating 0% at 20 °C or warmer, rising 1% per °C (20% at 0 °C), capped at 50%. Peukert, off by default: energy × (rated power / power)^(k − 1), where rated power = pack energy / rated discharge time

Show your work

1. Energy you may use

   usable = pack energy × usable share × (1 − cold derating)

   90.4 Wh × 80% × (1 − 0%) = 72.3 Wh

2. After the reserve

   $$\mathrm{flyable}=\mathrm{usable}\times (1-\mathrm{reserve})$$

   72.3 Wh × (1 − 0%) = 72.3 Wh

3. Hover time

   time = flyable energy × Peukert factor / hover power

   72.3 Wh × 1 / 151 W = 28.8 min

The same steps an agent gets from the MCP server with explain: true.

Accuracy: Only as good as the power figure. Wind, climbs, and aging packs shorten real flights.

When to use this: Use this when you know, or have estimated, the power a drone draws and want to know how long a pack will keep it in the air: it takes the usable share of the battery, removes a cold-weather derating and the reserve you land with, and divides by the power, for hover and cruise, and turns the cruise time into a range at your groundspeed.

Limitations: It is energy divided by power at a steady draw, so it is exactly as good as the power figure you give it. Climbs, wind, gusts, and payload changes raise the draw; a pack’s voltage sags as it empties and its capacity falls with age and at high current. The reserve here is a share of the usable energy, not of the whole pack, so 80% usable with a 20% reserve flies on 64%. The cold-battery derating is a rule of thumb, and range ignores wind: work the groundspeed out first.

Worked example: A 90.4 Wh pack, 80% usable, hovering at 150.6 W. Source: add-drone-suite endurance scenario: about 28.8 min.

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.

Changes

• 2026-09-23, changed: Drone flight time is stable. It reproduces the endurance step of Bauersfeld and Scaramuzza's DJI Mavic 3 example (IEEE Robotics and Automation Letters, 2022): 4.89 Ah at 4 × 3.7 V and 89.5 W is 2,909 s, and 4.88 Ah at 107.0 W is 2,429 s, both within the rounding of the printed capacity. The derating field's help now asks for a percent, like 15, where it used to suggest 0.85, which the tool would have read as 0.85%. The reserve's help now says it is a share of the usable energy, which is what the tool has always computed. Results are unchanged. Changelog

Checked against: 29 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.

Sources

• Principles of Helicopter Aerodynamics, Leishman, J. G., Cambridge University Press, 2nd edition. Chapter 2 (momentum theory: ideal hover power T^1.5/√(2ρA), figure of merit).
• Range, Endurance, and Optimal Speed Estimates for Multicopters, Bauersfeld, L., and Scaramuzza, D., IEEE Robotics and Automation Letters 7(2), Vol. 7, No. 2, pp. 2953-2960. Sec. VII-E, step 6 (endurance = effective capacity × nominal voltage / electrical power).