Betaflight tuning glossary: PID, filter and blackbox terms
This glossary defines the terms you meet when tuning a Betaflight quad’s PIDs and filters. Each entry gives a short definition, the CLI name where there is one, and a link to the guide that goes deeper. Defaults are for Betaflight 4.3 to 2026.6 unless stated.
Anti-gravity
Anti-gravity adds extra I-term for a moment when you change throttle fast, so the quad holds its attitude through punch-outs and chops. CLI: anti_gravity_gain. In 4.3 it is on a 0 to 30000 scale (default 3500). From 4.4 it is 0 to 250 (default 80), so values don’t convert between the two. See feedforward, I-term and TPA.
Bidirectional DShot
Bidirectional DShot lets the ESC send motor speed back to the flight controller over the same signal wire. The RPM filter and dynamic idle both depend on it. CLI: dshot_bidir (default OFF). It needs ESC firmware that supports it. See RPM filter setup.
Blackbox
Blackbox is Betaflight’s flight recorder. It stores gyro, setpoint, motor and PID data to onboard flash or an SD card, and a tuning tool reads it afterwards. How well the log shows noise and response depends on the logging rate and debug mode. CLI: blackbox_sample_rate (default 1/4 of the PID loop rate), blackbox_device. See blackbox logging for tuning.
D
D, the derivative gain, resists fast changes in rotation. It damps overshoot and propwash, but it also amplifies high-frequency noise, so too much D heats motors. CLI: d_min_<axis> up to 4.5 and d_<axis> from 2025.12 (base D, roll default 30). See Betaflight PID tuning.
D max
D max is the peak D that Betaflight raises D to during fast moves, while base D applies when the quad is flying gently. CLI: d_<axis> up to 4.5 and d_max_<axis> from 2025.12 (roll default 40). How strongly fast gyro movement pushes D toward D max is set by d_max_gain (default 37, and 0 in 2026.6). See the setting-name converter for the swap.
Debug mode
Debug mode picks an extra signal for blackbox to log. For tuning, the useful one is the unfiltered gyro, which shows noise before the filters. CLI: debug_mode (default NONE). On 4.3 and 4.4 GYRO_SCALED records it; 4.5 logs it as standard, and GYRO_SCALED was removed in 2025.12. See blackbox logging for tuning.
D-term lowpass
The D-term lowpass filters the noise out of the D calculation, which would otherwise be amplified into the motors. There are two stages. CLI: dterm_lpf1_static_hz (default 75), dterm_lpf1_dyn_min_hz (75), dterm_lpf1_dyn_max_hz (150) and dterm_lpf2_static_hz (150). Lower cutoffs mean cooler motors and more filter delay. See filter tuning.
Dynamic idle
Dynamic idle keeps the motors from spinning below a minimum rpm, so they keep control authority at low throttle and during dives. It uses motor speed from bidirectional DShot. CLI: dyn_idle_min_rpm (default 0, which is off). Setting it too high adds idle thrust and warms the motors.
Dynamic notch
The dynamic notch finds the strongest noise peaks in the gyro signal and removes them, following them as the motors speed up and slow down. CLI: dyn_notch_count (default 3), dyn_notch_q (300), dyn_notch_min_hz (100 from 4.4, 150 in 4.3) and dyn_notch_max_hz (600). With a working RPM filter, it handles what is left over, mainly frame resonance. See filter tuning.
Feedforward
Feedforward pushes the motors in the direction of your stick movement before the quad has moved, based on how fast you move the stick. It makes the quad feel more direct and cuts tracking lag, but too much causes overshoot at the end of a move. CLI: f_<axis> (roll default 120) plus the feedforward_* settings. See feedforward, I-term and TPA.
Filter delay
Filter delay is the time a filter adds between what the gyro senses and what the PID controller sees, measured in milliseconds. Heavier filtering means more delay, and more delay means a softer, later response and more propwash. It is the cost of cutting noise. See Betaflight filter tuning.
Frame resonance
Frame resonance is vibration at the frequency where your frame, arms or stack naturally shake, usually a fixed band that shows in the gyro spectrum whatever the throttle. Filters can reduce it, but a loose screw or soft arm makes it worse and tuning can’t fix it. The dynamic notch usually handles what remains. See filter tuning.
Gyro lowpass
The gyro lowpass removes high-frequency noise from the gyro signal before the PID controller sees it. There are two stages. CLI: gyro_lpf1_static_hz (default 250), gyro_lpf1_dyn_min_hz (250), gyro_lpf1_dyn_max_hz (500) and gyro_lpf2_static_hz (500). Higher cutoffs mean less delay but more noise. See filter tuning.
I
I, the integral gain, builds up when the quad stays off its target and pushes it back. It holds the attitude against wind, battery sag and an off-centre weight. Too much I makes the quad slow to settle. CLI: i_<axis> (roll default 80). See Betaflight PID tuning.
I-term relax
I-term relax stops the I-term from building up while you move the sticks quickly, so it doesn’t cause overshoot after a flip or roll. CLI: iterm_relax (default RP), iterm_relax_type (SETPOINT) and iterm_relax_cutoff (15). See feedforward, I-term and TPA.
Master multiplier
The master multiplier is the slider that scales P, I, D, D max and feedforward together, keeping their balance. At 100 you have the stock gains. CLI: simplified_master_multiplier (default 100). See Betaflight sliders.
Motor noise
Motor noise is vibration from the motors and props at a frequency that follows motor rpm, so it rises and falls with throttle. It shows in the gyro spectrum as lines that move. The RPM filter targets it directly. See RPM filter setup.
Motor poles
Motor poles is the number of magnets in the motor’s rotor. Betaflight uses it to turn the electrical rpm the ESC reports into real rpm, which the RPM filter needs. CLI: motor_poles (default 14). A wrong value puts the RPM filter notches at the wrong frequencies. See RPM filter setup.
Overshoot
Overshoot is how far the quad’s rotation goes past what you asked for before it settles, shown as a percentage of the step. A little is normal; a lot means too little damping, too much P or too much feedforward. See step response.
P
P, the proportional gain, pushes back in proportion to how far the quad is from the target rotation. More P means a tighter hold and a quicker response, but too much causes overshoot. CLI: p_<axis> (roll default 45, pitch 47). See Betaflight PID tuning.
Propwash
Propwash is the shaking you get when the quad flies through its own turbulent air, most often when you chop the throttle or come out of a dive or split-S. Good damping, low filter delay and a clean setup reduce it. See how to fix propwash.
RPM filter
The RPM filter removes motor noise by notching the exact frequencies the motors spin at, plus their harmonics, using rpm data from bidirectional DShot. CLI: rpm_filter_harmonics (default 3), rpm_filter_q (500) and rpm_filter_min_hz (100). It lets you filter less elsewhere. See RPM filter setup.
Settling time
Settling time is how long the quad takes after a step to stay near the target, in milliseconds. Long settling time means ringing or sluggish correction. It is one of the numbers a step response gives you, along with overshoot. See step response.
Simplified tuning
Simplified tuning is Betaflight’s slider mode, where a few multipliers set the gains and filter cutoffs instead of the raw PID table. CLI: simplified_pids_mode (OFF, RP or RPY; default RPY). While it is on for an axis, the sliders set that axis’s gains. See Betaflight sliders.
Step response
A step response shows how the quad’s actual rotation follows a sudden change in stick input. It reveals rise time, overshoot and settling time, so you can judge the balance of P, D and feedforward from a flight log. See step response.
TPA
TPA, throttle PID attenuation, reduces gains at high throttle to stop oscillation when the motors are working hardest. CLI: tpa_rate (default 65), tpa_breakpoint (1350) and tpa_mode (D). In 4.3 these sit in the rate profile; from 4.4 they are in the PID profile. 4.5 adds tpa_low_rate. See feedforward, I-term and TPA.