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The Drone Battery & Range Calculator estimates maximum safe flight time and effective range based on battery capacity (mAh), voltage (V), drone power draw (W), cruise speed (m/s), and headwind. Energy in watt-hours: capacity × voltage / 1000. Usable energy after typical 80% safe discharge: Wh × 0.8. Flight time minutes = usable Wh / power × 60. Safe flight time (with 30% reserve for return-to-home) = max time × 0.7. Range km = effective speed (cruise minus headwind) × safe flight time ÷ 60. Why 30% RTH reserve matters: when battery hits 30% remaining, most consumer drones (DJI, Autel) automatically trigger Return-to-Home. If you push past this without enough remaining capacity to make it back, drone lands wherever it runs out — often in water, traffic, or unreachable terrain. Lost drones from battery depletion are the #1 cause of consumer drone fatalities. Always plan flights assuming you need the RTH battery, especially over water, mountains, or unfamiliar terrain. Real-world ranges vary by drone class. DJI Mini 4 Pro (2453 mAh, 7.38V → 18 Wh): 34 min advertised, ~24 min safe, range ~10 km (in still air at 36 km/h). DJI Mavic 3 (5000 mAh, 15.4V → 77 Wh): 46 min advertised, ~32 min safe, range ~30 km. Autel EVO Lite+ (6175 mAh, 11.55V → 71 Wh): 40 min advertised, ~28 min safe. Manufacturer 'max flight time' assumes ideal conditions — perfect weather, no payload, smooth flight; reduce by 25–40% for real-world use. Wind effects: headwind reduces effective speed (and thus range) directly while increasing power consumption. A 15 m/s cruise drone facing 5 m/s headwind has 10 m/s effective forward speed AND draws ~20% more power. Tailwind increases range but creates risk on return leg. Crosswind doesn't change forward range but increases lateral drift consumption. Best practice: plan flights into the wind first, return downwind. Never fly out farther than you can return on remaining battery considering the prevailing wind.
Wh = (mAh × V) / 1000; Safe Time = Wh × 0.8 / Power × 60 × 0.7; Range km = (Speed − Wind) × Time / 60
- 1Step 1 — Enter battery capacity (mAh) from drone specification or battery label
- 2Step 2 — Enter battery voltage (typically 7.4V for small drones, 15.4V for mid-size, 22.2V for larger)
- 3Step 3 — Enter average power draw (W) during cruise (DJI Mini ~30W, Mavic 3 ~95W)
- 4Step 4 — Enter cruise speed (typical 10–18 m/s for consumer drones, 25+ for racing)
- 5Step 5 — Enter headwind speed (estimate from local weather or ask drone hover-and-observe)
- 6Step 6 — Calculator computes Wh = (C × V) / 1000, usable Wh = Wh × 0.8, flight time = Wh / P × 60
- 7Step 7 — Applies 30% RTH reserve for safe flight time; computes range from effective speed × time
Matches manufacturer claims approximately. Real-world reduces by 20–30% for wind, payload, cold weather.
5 m/s headwind cuts effective speed by 33%, reducing range significantly
Wind is the #1 factor reducing real-world range. Always plan for current wind, not advertised range.
Mountain flying adds turbulence overhead — derate calculator by 20%.
Pre-flight planning for photography/inspection missions
Choosing drone model for distance requirements
Battery purchase decisions for working drones
Multi-battery planning for extended jobs
Insurance documentation of flight planning practices
Training new pilots on battery safety
Why is real-world range so much less than advertised?
Manufacturer 'max flight time' assumes: no wind, ideal temperature (20°C), no payload, smooth flight, fresh battery. Real conditions reduce by 20–40%: wind costs energy (headwind dramatically), cold below 10°C reduces lithium chemistry capacity by 20–30%, fast or aggressive flight burns more power, camera/gimbal payload adds drag. Always reduce manufacturer claims by 25% for planning.
How much reserve battery is enough?
30% minimum for return-to-home. More for: long missions over water (50%), unfamiliar terrain (40%), high altitude reducing motor efficiency (40%), cold weather (40%). Most drones auto-RTH at 30%; you can override but shouldn't unless you have visual confirmation of safe landing zone within remaining capacity.
What kills battery life fastest?
Aggressive flying (sport mode at full throttle), cold weather, full payload, headwind, high altitude. Combined effect: cold + windy + sport mode can cut advertised flight time in half. Hover uses about 70–80% of max-throttle power; gentle forward flight is often most efficient (10–12 m/s).
How do I extend range?
(1) Fly into wind first, return with tailwind. (2) Plan altitude — battery dies faster at high altitudes (less air density). (3) Use smaller, more efficient drone if range is critical. (4) Carry spare batteries — landing to swap takes <2 min. (5) Avoid hover — forward flight 10–15 m/s is most efficient. (6) Reduce gimbal/camera activity (4K recording uses more power than 1080p).
Do lithium batteries degrade over time?
Yes. Expect 20–30% capacity loss after 200–300 charge cycles, 50% after 500–800 cycles. Storage matters: store at 50% charge in cool dry place; full or empty long-term degrades batteries fastest. DJI Intelligent Flight Batteries have built-in storage discharge (auto-discharge to ~70% after 10 days idle). Replace batteries showing >25% capacity loss for safety.
プロのヒント
Always plan flights into the wind first, return with tailwind. Plan max outbound distance assuming current wind doubles by return time — weather can shift faster than you can fly home. When in doubt, fly closer; lost drones cost $500–8,000 to replace.