Quick Answer
Betaflight filters clean noise from your gyro and motor signals before the PID controller processes them. The two main types are low-pass filters (LPF), which remove high-frequency vibration, and dynamic notch filters, which target motor noise at specific frequencies. Correct filter settings reduce motor heat, eliminate oscillation, and improve flight feel.
Why Filters Matter in Betaflight
Your flight controller's gyro picks up more than just movement. Motor vibration, prop wash, and frame resonance all generate noise that confuses the PID loop. Without filtering, your drone oscillates, motors run hot, and flight performance suffers.
Filters sit between the raw gyro signal and the PID calculations. They strip out unwanted frequencies while preserving real motion data. The key principle: use the minimum filtering needed. Too much adds latency, making your drone feel mushy. Too little leaves noise that burns out motors.
Low-Pass Filters (LPF)
Low-pass filters allow signals below a set frequency to pass through while blocking higher frequencies. Betaflight applies LPF at two stages: the gyro filter and the D-term filter.
Gyro LPF
The gyro low-pass filter (LPF 1 and LPF 2) removes high-frequency noise from the gyro signal. The default LPF 1 cutoff is around 200 Hz, and LPF 2 is typically disabled or set high. For most freestyle builds with quality flight controllers like the SpeedyBee F405 V5 stack, the defaults work well. Only lower the gyro LPF if you see noise in your blackbox logs above your desired cutoff.
D-Term LPF
The D-term is the most noise-sensitive part of your PID controller. It amplifies high-frequency signals, so it needs its own filtering. Betaflight provides D-term LPF 1 and LPF 2. The first stage uses a biquad or PT1 filter (PT1 is preferred for lower latency). The second stage is a dynamic filter that adjusts based on throttle position.
Common starting point: D-term LPF 1 at 100 Hz with PT1 type. Adjust from there based on blackbox analysis.
Dynamic Notch Filters
Dynamic notch filters are one of the most important filtering tools in modern Betaflight. They automatically track and notch out motor noise frequencies, which change as your motors spin faster or slower.
In Betaflight 4.x and later, dynamic notch filters are enabled by default and work well out of the box. The key settings are the number of notches (default 2) and Q factor (higher Q means narrower notches). Most pilots should leave these at defaults.
Reading Blackbox Logs for Filter Tuning
Blackbox logging is your primary tool for evaluating filter performance. A blackbox log records gyro data, PID outputs, and motor signals during flight. View the data in Blackbox Explorer and check for clean gyro traces. Sharp peaks at specific frequencies mean your notch filters need adjustment. A well-filtered setup shows noise floors around -40 dB or lower.
Practical Filter Tuning Steps
Start with Betaflight defaults. Fly a full-throttle punchout and a hover, then check your blackbox log. If the gyro trace is clean, you are done. If noisy, try these steps in order:
- Ensure your frame is mechanically sound (no loose screws, balanced props). Hardware fixes beat software filtering every time.
- Lower the gyro LPF 1 by 20-30 Hz at a time until noise subsides.
- Adjust D-term LPF 1 cutoff. A PT1 filter at 80-100 Hz is a good range for most builds.
- Only then adjust dynamic notch settings if specific frequency peaks persist.
Flight controllers with better gyros (ICM42688P, such as on the AxisFlying Argus Eco stack) generally need less filtering than older MPU6000-based boards, because the sensor itself produces less noise.
For a full walkthrough, see the Betaflight flight controller setup guide. Also check our AIO vs stack flight controllers comparison to understand how your hardware choice affects filtering needs.
FAQ
Q: Should I disable RPM filters for racing?
A: No. RPM filtering (if your ESCs support bidirectional DSHOT) is one of the most effective noise-reduction tools available. It provides motor-frequency-specific filtering with minimal latency. Always enable it when possible.
Q: What happens if I set filters too low?
A: Over-filtering adds latency between your drone's movement and the flight controller's response. Your quad will feel sluggish, disconnected, and imprecise. In extreme cases, it can cause a wobble at low frequencies because the PID loop cannot react fast enough.
Q: Do I need different filters for freestyle vs racing?
A: The defaults work for both. Racing pilots sometimes run slightly less filtering to reduce latency, but only after confirming clean blackbox logs. Freestyle pilots benefit from slightly more filtering since smoothness matters more than absolute responsiveness.