Agricultural Spray Drone Calculator
Calculate spray coverage, chemical usage, and mission time for agricultural spraying drones based on tank capacity, application rate, and field size.
About this calculator
Planning an agricultural spray drone mission comes down to two independent limits that rarely line up: how much chemical the tank holds (which sets how many acres one load can cover) and how long the battery lasts (which sets how long the drone can fly before it needs a swap). This calculator keeps those two constraints separate rather than collapsing them into one number -- acres per tank load comes purely from tank capacity divided by the application rate you set, while the effective spray time per load is whichever of the two runs out first, the battery or the tank -- tank duration comes from dividing tank capacity by the total flow rate (the flow rate per nozzle you enter from the nozzle's spec sheet, multiplied by nozzle count), a genuinely independent measurement from the battery's rated flight time, so the two limits can actually diverge rather than always landing on the same number. Ground speed and swath width together set the drone's coverage rate in acres per hour using the standard area-rate conversion (speed in mph times swath in feet times 0.1212, which comes from converting 5,280 feet per mile into the 43,560 square feet in an acre); this rate is independent of the tank and chemical settings entirely, so a faster ground speed always increases acres covered per hour even if it has no effect on how many tank loads the field requires.
Total mission time adds up active spray time, a fixed reload allowance for each tank refill, and a smaller allowance for each battery swap, reflecting that reloading chemical and swapping batteries both interrupt a real spray operation even though they don't consume spray chemical or airtime themselves. Because application rate (L/acre) is set by the label instructions for whatever chemical you're using, always cross-check the calculated coverage against your product label and your agronomist's prescribed rate before a real mission -- this calculator computes the logistics of a given rate, not what the correct rate should be for a specific crop or pest.
Inputs
Results
Acres per tank load
5
How to Use This Calculator
- Enter tank capacity (L), application rate (L/acre), and total field area (acres).
- Set ground speed (mph), swath width (ft), and nozzle count for your spray drone.
- Enter chemical cost per liter, battery flight time (min) per charge, and the flow rate per nozzle (L/min) from your nozzle's spec sheet.
- Review acres per tank load, total tank loads needed, chemical cost, and acres covered per hour.
- Compare tank duration and spray time per load to see whether the tank or the battery limits each load, then check total mission time and battery swaps needed against your agronomist's prescribed rate for the target crop.
How the result changes with Application rate (L/acre)
| Application rate (L/acre) | Acres per tank load |
|---|---|
| 1 | 10 |
| 1.5 | 6.67 |
| 3 | 3.33 |
| 5 | 2 |
What each input means
- Tank capacity (L)
- Spray tank volume in liters (e.g., DJI Agras T40 = 40 L).
- Application rate (L/acre)
- Chemical application rate in liters per acre. Typical range 0.5-5 L/acre for ULV spraying.
- Field area (acres)
- Total field area to be sprayed.
- Ground speed (mph)
- Drone ground speed during spraying. Typical 8-15 mph.
- Swath width (ft)
- Effective spray swath width from all nozzles. Depends on nozzle spacing and flight height.
- Chemical cost ($/L)
- Cost of spray chemical per liter.
- Battery flight time (min)
- Flight time per battery under spray load. Typically 8-15 min.
- Nozzle count
- Number of spray nozzles on the drone.
- Flow rate per nozzle (L/min)
- Rated output of a single nozzle at your spray pressure (check the nozzle/drone spec sheet). Typical ULV agricultural nozzles run roughly 0.2-2 L/min each.
What each result means
- Acres per tank load
- How many acres one full tank can cover.
- Tank loads needed
- Total refills required to spray the entire field.
- Total chemical (L)
- Total volume of spray chemical needed.
- Chemical cost ($)
- Total cost of spray chemicals for the field.
- Acres per hour
- Spray coverage rate based on speed and swath width.
- Tank duration (min)
- How long a full tank lasts at the total nozzle flow rate (flow rate per nozzle x nozzle count), independent of the battery.
- Spray time per load (min)
- Effective spraying time per load -- whichever runs out first, the battery or the tank.
- Total spray time (min)
- Total active spraying time for the entire field.
- Battery swaps
- Number of battery changes needed during the mission.
- Total mission time (min)
- Total time including spraying, reloading, and battery swaps.
How this is calculated
Worked example, using the default values
- Identify Input Parameters9 parametersTank capacity (L) = 10, Application rate (L/acre) = 2, Field area (acres) = 40, Ground speed (mph) = 10, Swath width (ft) = 15, Chemical cost ($/L) = 5, Battery flight time (min) = 12, Nozzle count = 4, Flow rate per nozzle (L/min) = 0.5 = 9 input(s) provided
- Calculate Acres per tank loadAcres per tank load = tankCapacityL / applicationRateLPerAcre5 = 5
- Calculate Tank loads neededTank loads needed8 = 8
- Calculate Total chemicalTotal chemical = fieldAreaAcres * applicationRateLPerAcre80 = 80
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why doesn't field area affect acres per tank load?
Acres per tank load is simply tank capacity divided by the application rate -- it describes how much ground one full tank can cover at a given chemical concentration, which has nothing to do with how large the field you're spraying happens to be. Field area is brought in on the next step instead, where the total field size gets divided by acres-per-load to determine how many tank refills the mission requires.
Why does chemical cost not change the drone's coverage rate?
Acres per hour is a function of ground speed and swath width only -- how fast the drone physically moves across the field and how wide a strip each pass covers -- and has nothing to do with what the chemical costs per liter. Chemical cost feeds into the total chemical cost output, which scales directly with field area and application rate, but the coverage-rate math and the cost-per-liter math are entirely separate calculations that don't interact.
What determines whether the tank or the battery limits spray time per load?
This calculator computes both limits independently and takes whichever is shorter: tank duration is the tank capacity divided by the total nozzle flow rate (the flow rate per nozzle you enter, from the nozzle's own spec sheet, times nozzle count), while battery duration is simply the battery's rated flight time. Because flow rate per nozzle is a real, separately-entered spec rather than something derived from the battery, the two limits genuinely can diverge -- a large tank with a low flow rate and a short battery will be battery-limited, while a small tank with a high flow rate and a long-lasting battery will be tank-limited. Check the "Tank duration" and "Spray time per load" outputs together to see which constraint is binding for your setup.
Why does total mission time include time for reloads and battery swaps?
Active spraying is only part of a real mission -- every tank refill means landing, mixing or loading more chemical, and taking off again, and every battery swap means landing to physically change batteries. This calculator adds a fixed allowance for each tank reload and a smaller allowance for each battery swap on top of the active spray time, because ignoring that overhead would understate how long the mission actually takes on the ground.
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