🎚️ Crossover Calculator
Get the capacitor and inductor values for a passive first- or second-order crossover from your crossover frequency and driver impedance — the high-pass cap for the tweeter and the low-pass inductor for the woofer.
🎚️ Crossover components
A first-order network is one component per driver (6 dB/octave) and gives the gentlest slope. Use a non-polarised (bipolar) capacitor on the tweeter and an air-core inductor on the woofer, rated for the driver impedance shown.
Send each driver the band it plays best
A crossover splits the signal so the tweeter only sees the highs and the woofer only the lows. Get it right and the system sounds clean and effortless; get it wrong and you either muddy the sound or feed a tweeter bass that will kill it. From your crossover frequency and driver impedance this tool gives the passive component values — a high-pass capacitor for the tweeter and a low-pass inductor for the woofer.
Pair it with the SPL Calculator to compare how loud each driver plays, and the Amplifier Power Calculator to size the amp behind them.
❓ Frequently Asked Questions
What are the first-order crossover formulas?
A first-order (6 dB/octave) crossover uses one component per driver. The high-pass capacitor that protects the tweeter is C = 1 / (2π × f × Z), and the low-pass inductor that rolls off the woofer is L = Z / (2π × f), where f is the crossover frequency in hertz and Z is the driver impedance in ohms. At 2500 Hz into 4Ω that's about 15.92 µF and 0.255 mH.
How does a second-order crossover differ?
A second-order (12 dB/octave) Butterworth crossover uses a capacitor and an inductor per driver for a steeper slope and better driver protection. The values scale the first-order ones by √2: the high-pass capacitor becomes C = 1 / (2π × f × Z × √2) and the inductor becomes L = (Z × √2) / (2π × f). The steeper slope keeps highs out of the woofer and lows out of the tweeter more effectively.
Which component goes on which driver?
Tweeters get a high-pass capacitor in series, which blocks the low frequencies that would otherwise destroy them. Woofers get a low-pass inductor in series, which blocks the high frequencies they can't reproduce cleanly. Use a non-polarised (bipolar) capacitor and an air-core inductor rated for your driver impedance, and mind the tweeter's polarity when you wire it.
What crossover frequency should I choose?
It depends on your drivers: a common starting point for a component set is around 2.5–3.5 kHz, kept above the tweeter's rated minimum and within the woofer's usable range. Pick a frequency both drivers handle comfortably, then listen. This tool covers passive networks; many head units and amps also offer adjustable active crossovers that need no components.