Quick summary
The numbers 1303, 1404, 2207 and 3115 are shorthand for a brushless motor’s stator dimensions. The first two digits give the stator diameter in millimetres and the last two give the stator height in millimetres. So a 2207 has a 22 mm stator diameter and a 7 mm stator height. These dimensions tell you far more about a motor’s torque, acceleration and likely role than the brand name on the bell.
Key Takeaways
- Brushless motor size codes describe stator diameter and height, not the outside of the motor.
- Larger diameter improves torque and efficiency; greater height adds torque but can increase drag.
- A 3115 is usually a large-propeller or multirotor motor, while a 1303 is a small, light build motor.
- Propeller size, battery voltage and takeoff weight must be matched to the motor, not chosen in isolation.
- For drone soccer teams, consistent motor batches and clear specifications matter as much as raw performance.
What the four-digit brushless motor code actually measures
The code refers to the stator, the fixed part of the motor carrying the copper windings. It does not measure the rotating bell, the shaft length or the mounting pattern. That is why two motors with the same 2207 code can still look different from the outside.
Stator diameter is the first two digits and stator height is the last two. A 1404 therefore has a 14 mm diameter and a 4 mm height. A 3115 has a 31 mm diameter and a 15 mm height. The convention is widely used across the FPV and multirotor market, though some manufacturers publish slightly different naming. Always confirm in the datasheet.
Why the stator, not the bell, is the useful number
The stator sets the electromagnetic working area. A wider stator gives the magnets and windings more leverage, which generally increases torque. A taller stator adds more winding volume and can raise torque further, but it also increases frontal area and drag. That is why a 2207 and a 2208 can feel different in flight even though their diameter is the same.
What the code does not tell you
The code does not specify KV (the motor’s RPM per volt), winding, magnet grade, bearing type, shaft diameter or weight. Two 2207 motors from different suppliers can have very different KV ratings and performance. Treat the size code as a starting point, then read the full specification.
1303 vs 1404 vs 2207 vs 3115: a practical comparison
The table below summarises the typical role of each size. These are general engineering tendencies, not fixed rules. Actual performance depends on KV, propeller, battery and all-up weight.
| Motor code | Stator size | Typical role | Relative torque | Typical propeller range | Notes for teams |
|---|---|---|---|---|---|
| 1303 | 13 mm × 3 mm | Small, light builds; indoor or micro aircraft | Low | Small 2–3 inch class | Light and efficient; sensitive to weight |
| 1404 | 14 mm × 4 mm | Sub-250 g and lightweight freestyle | Low to moderate | 3 inch class | Good balance for compact school builds |
| 2207 | 22 mm × 7 mm | 5 inch FPV and sport multirotors | Moderate to high | 5 inch class | Common baseline for club FPV |
| 3115 | 31 mm × 15 mm | Large propellers, heavy lift or cinematic multirotors | High | Large multirotor props | Higher current draw; check ESC and battery limits |
For school programmes, the 1303 and 1404 sizes are often easier to manage because they suit smaller airframes and lower energy systems. For drone soccer, where the ball and cage add mass, the right choice depends on the competition class and the airframe design. Confirm the class rules before standardising a motor.
How stator size affects torque, efficiency and heat
Larger stator dimensions generally increase torque and can improve efficiency at a given load, but they also add mass and current draw. The right size is the smallest motor that meets the torque demand without overheating.
Torque and acceleration
Torque is what lets a motor spin up a propeller quickly. In drone soccer, rapid direction changes and climbing around the goal depend on responsive torque. A larger stator usually responds better to a heavier propeller, but only if the battery and ESC can supply the current.
Efficiency and flight time
A motor running near its efficient load range wastes less energy as heat. Oversized motors on small propellers can be inefficient because they run at low throttle. Undersized motors on large propellers struggle and overheat. Matching is the key, which is why motor, propeller and battery matching deserves real attention.
Heat and durability
Small stators pushed hard will heat up faster. Heat degrades magnets and bearings over time, which is a real concern for school fleets that are used repeatedly. If a motor comes down hot after a normal flight, the propeller or battery may be too large for it.
Why the same numbers can feel different in flight
Two motors labelled 2207 can behave differently because KV, winding, magnet quality, bearing type and weight all vary. KV is the motor’s RPM per volt, so a higher-KV motor spins faster on the same battery but produces less torque per amp. A lower-KV motor turns a larger propeller more efficiently.
This is why buying on the size code alone is risky. Ask suppliers for a full datasheet with KV, weight, internal resistance if available, recommended propeller range, maximum current and recommended ESC. For custom projects, DPF’s motor and propulsion matching service can help align these parameters before ordering.
Matching motor size to a drone soccer or school programme
Start with the airframe and competition class, then choose a motor that fits the propeller and battery you are allowed to use. Do not start with the motor and build around it unless you have freedom to design the whole system.
A simple matching sequence
- Confirm the class rules for propeller size, battery voltage and weight.
- Estimate all-up weight including the ball, cage and any payload.
- Choose a propeller size allowed by the rules and suited to the weight.
- Select a motor size and KV that can turn that propeller at the required thrust without excessive heat.
- Check the ESC current rating and battery discharge capability.
- Test one unit before committing to a team kit order.
For organisations ordering for multiple teams, consistent batches matter. Small variations between batches can change flight feel and complicate coaching. Ask the supplier how they manage batch consistency and what documentation they provide.
Where 1303, 1404, 2207 and 3115 fit
A 1303 is best thought of as a light indoor or micro motor. A 1404 suits compact outdoor builds and sub-250 g projects. A 2207 is a common all-round 5-inch FPV motor. A 3115 belongs on larger multirotors with big propellers, where current draw and ESC selection become critical. None of these is inherently better; they serve different airframes.
If you are building or refreshing a fleet, browse DPF’s FPV motors and propulsion combo kits to see how motors, ESCs and propellers are grouped. Combo kits can reduce mismatching risk for groups that do not have engineering support.
Common mistakes when reading motor sizes
Most sizing errors come from treating the four-digit code as a complete specification. It is not. Watch for these pitfalls.
- Assuming bigger is better. A 3115 on a small airframe adds weight and drag and may be less efficient.
- Ignoring KV. A high-KV 2207 and a low-KV 2207 are different tools. KV changes thrust, current and propeller suitability.
- Forgetting the propeller. Motor and propeller are a pair. A motor that works well with one propeller may overheat with another.
- Overlooking the battery. Voltage and discharge capability set the ceiling for current. An under-specified battery will sag and may be stressed.
- Buying mixed batches. For teams, inconsistent motors can make identical drones feel different and frustrate coaching.
- Skipping the datasheet. Without weight, maximum current and recommended propeller data, you cannot verify a match.
Lithium battery safety is a separate but related issue
Motor choice affects current draw, which affects battery stress. Lithium-ion batteries can overheat and undergo thermal runaway if damaged, overcharged or improperly packed, according to the FAA’s lithium battery guidance. That page is written for air passengers and is not a drone operations manual, but it is a useful reminder to protect packs and terminals during storage and transport. For school programmes, include battery handling in team training.
Procurement checklist for teams, schools and distributors
Use this checklist before confirming a motor order. Items marked as verification steps should be confirmed in writing with the supplier rather than assumed.
- Competition class or curriculum requirements for propeller size, voltage and weight.
- All-up weight estimate for a ready-to-fly aircraft, including ball and cage.
- Required thrust-to-weight margin for the flying style and safety policy.
- Motor size code and KV, confirmed on the datasheet.
- Stator dimensions, motor weight and shaft diameter.
- Recommended propeller range and maximum current.
- Recommended ESC current rating and battery cell count.
- Mounting pattern and connector type for the airframe.
- Batch consistency policy: ask how batches are controlled and whether units can be supplied from one production run.
- Documentation supplied with the order: request datasheets, labelling and any test records the supplier offers.
- Spares ratio: confirm how many spare motors and arms you want per team.
- Commercial terms: request price validity, payment terms, shipping method and any warranty in writing.
DPF does not publish blanket MOQ, lead time or warranty terms in this article because they vary by product and order. Request a written quotation for your specific requirement and confirm those terms before committing.
Frequently asked questions
What does 2207 mean on a brushless motor?
It means the stator is 22 mm in diameter and 7 mm in height. It is a common size for 5-inch FPV motors. The code does not state KV, weight or winding, so check the datasheet.
Is a 3115 motor stronger than a 2207?
Generally a 3115 has a larger stator and can produce more torque, which suits larger propellers. That does not automatically make it better for a given aircraft; weight, drag and current draw must also be considered.
Can I use a 1303 motor for drone soccer?
It depends on the competition class and airframe. A 1303 is a small, light motor, so it suits small and light builds. Check the class rules for propeller size and weight before choosing it for a team.
How do I choose KV for a 1404 motor?
KV should be chosen together with the propeller and battery voltage. Ask the supplier for their recommended combination and verify with a test unit before ordering a fleet.
What should I ask a supplier before ordering team motors?
Ask for the full datasheet, recommended propeller and ESC, maximum current, batch consistency policy and written commercial terms. Request samples for evaluation where possible.
Do motor sizes determine flight time?
Not on their own. Flight time depends on the whole propulsion system, all-up weight and flying style. An efficient match between motor, propeller and battery matters more than the size code alone.
How should schools store and handle lithium batteries?
Follow the battery manufacturer’s instructions and your local regulations. The FAA passenger guidance notes that terminals should be protected from short circuit and damaged batteries should not be carried aboard aircraft. Treat that as general safety context, not a substitute for local rules.
Conclusion
Motor codes such as 1303, 1404, 2207 and 3115 describe stator diameter and height, which is a useful starting point for comparing brushless motors. They do not replace a full specification. For schools, clubs and drone soccer teams, the safest approach is to match motor, propeller, battery and ESC to the airframe and class rules, then confirm the details in writing with the supplier.
If you are planning a team kit or a multi-team purchase, request a quote with your airframe and class details so the propulsion set can be reviewed as a system.