The drone flight time calculator above divides the energy you are genuinely willing to take out of a pack by the rate you take it out at. That is the whole of the physics. Everything difficult about the question lives in the two inputs, and this page is built to make that obvious rather than to hide it behind a confident number.
Arb Digital builds free calculators that state their assumptions instead of burying them. Flight time estimators are unusually prone to flattering results, because using nameplate capacity and hover current together can easily double the answer. This one asks for a usable fraction and an average current, tells you what the nameplate figure would have been, and shows the gap.
What This Drone Flight Time Calculator Does
It works in two modes. In current mode you supply an average current draw, which is the accurate route if you have a flight log, a power module or an in-line watt meter. In weight mode it derives a hover current from your all-up weight and a hover efficiency figure in grams of thrust per watt, which you must take from your own motor manufacturer’s published thrust data.
That second field starts at zero and stays there until you fill it in, and the page ships no thrust table of any kind. There is a reason for that. Thrust and efficiency figures are specific to one motor, one propeller, one cell count and one throttle position, and a table copied from somewhere else is not a measurement of your aircraft. Publishing one would make this tool look more helpful and be less accurate.
Alongside the headline, the calculator reports usable capacity, pack energy in watt-hours, the average C-rate the load represents, and what the flight time would have been on the full nameplate capacity. That last figure is there for comparison, not for use.
How to Use It
- Enter the pack capacity, the cell count and the nominal volts per cell. Nominal is 3.7 V for lithium polymer and lithium-ion cells; change it if you fly a different chemistry.
- Set the usable percentage. This is your reserve policy, not a property of the battery, and it is the input most worth thinking about.
- In current mode, put in an average current from a logged flight rather than a peak or a hover figure.
- In weight mode, enter the all-up weight with battery, camera and everything else fitted, and a grams-per-watt figure from your own motor data.
- Compare the headline against the nameplate figure in the grid. The difference is the optimism you have just removed.
The Formula: How It Is Calculated
The core relation is flight time in minutes = (capacity in Ah × usable fraction) ÷ average current in A × 60.
Work through the defaults. A 5,000 mAh pack is 5.0 Ah. At 80% usable that is 4.0 Ah. At an average draw of 20 A, the time is 4.0 ÷ 20 = 0.2 hours, which is 12.0 minutes. On the full nameplate 5.0 Ah it would have been 15.0 minutes, so the reserve policy alone costs three minutes.
Pack energy is capacity multiplied by nominal pack voltage. Four cells at 3.7 V is 14.8 V, so 5.0 Ah × 14.8 V = 74 Wh, of which 59.2 Wh is usable. The average C-rate is current divided by capacity in amp-hours, so 20 ÷ 5 = 4C.
Weight mode inserts one step. Hover power in watts is all-up weight in grams ÷ efficiency in g/W, and hover current is that power divided by pack voltage. A 1,200 g aircraft at a hover efficiency of 8 g/W would need 150 W, which on a 14.8 V pack is about 10.1 A — but only if 8 g/W is a figure you took from your own motor’s thrust table, which is why the field starts empty.
Why Nameplate Capacity Is Not Usable Capacity
Three separate effects sit between the number printed on the pack and the energy you can actually fly on, and they compound.
The first is the reserve. Lithium polymer cells are damaged by deep discharge, and a multirotor that runs its pack flat falls out of the sky rather than coasting to a stop. Landing with a fifth of the pack unused is normal practice, not caution.
The second is that rated capacity is measured at a gentle discharge rate. Pull a pack hard and it delivers less than its rating before hitting the same voltage, because internal resistance drops the terminal voltage under load. A pack that tests at 5,000 mAh at 1C may return noticeably less at 10C.
The third is age. Cycled packs lose capacity and gain internal resistance, and a two-year-old pack that has been stored charged is not the pack it was. None of these are modelled separately here; they are all folded into the one usable percentage field, which is honest about being a judgement rather than a measurement. Our battery capacity calculator covers pack sizing in more general terms if you want to work the other way round.
Hover Draw Is Not Cruise Draw
The single most common way to overestimate flight time is to measure current in a stationary hover and then apply it to a flight that was nothing like a hover. Forward flight, climbing, wind, and any kind of aggressive manoeuvring all raise the draw, and on a small quadcopter the difference between a calm hover and normal sport flying can be a factor of two or more.
Climbing is the extreme case, because climbing at any speed requires thrust well above weight and power rises faster than thrust does. Wind is the underestimated one: holding position in wind is not free, and a drone that appears to be hovering in a breeze is flying forward into it at the wind speed and drawing accordingly.
The practical fix is to take your average from a whole logged flight of the kind you actually fly, not from a bench test. If your flight controller records pack current, the average over the flight divided into the capacity consumed will give you a figure that already includes all of this. Failing that, treat a hover-derived estimate as a ceiling that real flights will not reach.
What Payload Does to the Answer
Adding weight to a multirotor costs more than the weight suggests, because heavier means more thrust, more thrust means more power, and the relationship between thrust and power is not linear — power rises roughly with thrust to the power of 1.5 in simple momentum theory. Adding 20% to the all-up weight costs appreciably more than 20% of the endurance.
This is also why adding a bigger battery does not always help. A larger pack carries more energy but also weighs more, and beyond a certain point the extra weight consumes the extra energy. There is an optimum pack size for any given airframe, and it is found by testing rather than by algebra, because it depends on the same motor and propeller efficiency curve that this page refuses to guess at. Our drone motor thrust calculator handles the thrust-to-weight side of that question, including hover throttle, which is the number that tells you whether the aircraft has any margin left at all.
How This Differs From the Battery Tools
Our battery life calculator is a general energy-divided-by-power tool for consumer electronics, sensors and power banks. It handles depth of discharge and efficiency losses, but it does not know anything about hover current, all-up weight, C-rate in a flight context or the reserve conventions multirotor pilots use. This page is that same division specialised for a drone, with the aviation-specific traps written into the interface.
The battery charge time calculator answers the other half of the day: how long before you can fly again. The electrical power calculator is useful for converting between volts, amps and watts if your figures arrive in mixed units.
Flying Legally Is Not Part of the Arithmetic
Endurance is a physics question. Whether you may fly at all, where, and how far from yourself, is a legal one, and the operator is responsible for getting it right. In the United States the Federal Aviation Administration publishes the requirements for recreational flyers, covering registration, altitude, airspace authorisation and keeping the aircraft within visual line of sight. In the United Kingdom the Civil Aviation Authority sets out the equivalent framework on its drones pages. Other countries have their own regulators and their own rules.
The practical connection to this calculator is simple: a longer estimated flight time is not permission to fly further away. Visual line of sight limits range regardless of endurance, and planning a flight that consumes the whole usable capacity leaves nothing for a headwind on the way home.
Arb Digital designs and builds free interactive calculators that state their assumptions, refuse to invent constants, and earn links because they are genuinely useful. Browse what we have already published, or tell us what your audience keeps searching for.
Browse the Free Tools Hub Talk to Arb DigitalCommon Mistakes to Avoid
- Using nameplate capacity. It ignores the reserve you should be landing on and the capacity a pack loses under a heavy load. Set a usable percentage and live with the smaller number.
- Using hover current for a flight that was not a hover. Forward flight, climbs and wind all raise the draw, often by a factor of two.
- Borrowing an efficiency figure from a different motor or propeller. Grams per watt is specific to one combination at one voltage. A figure from elsewhere is not data about your aircraft.
- Assuming a bigger pack means longer flight. The extra weight costs power, and past the optimum the added capacity does not pay for the mass carrying it.
- Planning to use the whole estimate. A headwind on the return leg, a diversion, or a warmer day than expected all eat into it. The estimate is a ceiling, not a plan.
Related Free Tools From Arb Digital
Pair this with the drone motor thrust calculator for the thrust-to-weight and hover throttle side of the same aircraft. On batteries, the battery life calculator covers general electronics, the battery capacity calculator helps size a pack, and the battery charge time calculator tells you when you can fly again. The electrical power calculator converts between volts, amps and watts, and the air density calculator is worth a look if you fly somewhere high or hot, since thinner air costs endurance. Everything else is on the free online tools hub.
Frequently Asked Questions
Multiply the pack capacity in amp-hours by the fraction you are willing to use, divide by the average current draw in amps, and multiply by 60 for minutes. A 5,000 mAh pack at 80% usable, drawing an average of 20 A, gives 4.0 divided by 20 times 60, which is 12 minutes.
Because you should not fly a lithium polymer pack flat, and a pack under heavy load returns less than its rated capacity anyway. The usable percentage folds the reserve, the load derating and pack age into one honest judgement rather than three hidden ones.
Because thrust and efficiency figures apply to one specific motor, propeller, cell count and throttle setting. A table copied from elsewhere would look authoritative and describe a different aircraft, so the efficiency field starts at zero and expects a figure from your own manufacturer's published data.
Neither, if you can avoid it. Use the average current over a whole logged flight of the kind you actually fly. Hover draw is substantially below cruise draw, and estimates built on hover figures come out optimistic, often by a factor approaching two.
Up to a point. A larger pack carries more energy but weighs more, and heavier flight costs power faster than linearly, so beyond an optimum the extra mass consumes the extra energy. The optimum depends on your motors and propellers and is found by testing.
C-rate is the current divided by the capacity in amp-hours, so 20 A from a 5 Ah pack is 4C. It matters because packs deliver less than their rated capacity at high C-rates and because exceeding a pack's rated discharge is how packs are damaged.
No. Range is limited by the rules you fly under, which in most countries require the aircraft to stay within visual line of sight, and by the need to keep enough reserve to get home against a headwind. Endurance and permitted range are separate questions.
This page produces an estimate, not a specification. Real endurance depends on the flying you do, the wind, the temperature, the age of the pack and the efficiency of your particular motor and propeller combination, none of which a calculator can measure for you. Drone flight is regulated, and the operator is responsible for registration, airspace, altitude and line-of-sight rules in their own country.
