Acoustics, audio & electronics calculators that respect you
Free, fast, accurate, and permanently ad-free. Every tool shows its formulas, works on your phone, and produces a shareable link to your exact result.
Room mode calculator
Axial, tangential and oblique standing waves for any rectangular room, with problem-frequency flags.
Reverberation time (RT60)
Sabine and Eyring RT60 across six bands from your room's surfaces, with treatment suggestions.
Speaker crossover calculator
Passive 2-way component values — Butterworth, Linkwitz-Riley, Bessel — with schematic and E12 parts.
Speaker box calculator
Sealed and ported enclosure volumes, tuning and port length from Thiele/Small parameters.
Port velocity calculator
Air speed in a bass-reflex port, where it peaks, and the length that buys silence — because velocity × length is a constant.
Delay & BPM calculator
Note-value delay times, LFO rates, samples, and distance-to-milliseconds with tap tempo.
Speaker wiring calculator
Series, parallel and series-parallel impedance for 2–8 speakers, with a safe-load check against your amp.
Speaker SPL calculator
Predicted loudness at any distance from sensitivity and power, with boundary placement gain and a distance ladder.
Decibel converter
dBu, dBV, dBm, dBFS and volts in every direction, with digital alignment levels and a dB ↔ ratio calculator.
Speaker cable calculator
Wire gauge for any run: loop resistance, power lost, level loss in dB and the damping factor that reaches the speaker.
RC & RL filter calculator
First-order low-pass and high-pass: cutoff, time constant, gain and phase, Bode plot, and the E12/E24 part you actually need.
LC resonance calculator
Series and parallel tanks: resonant frequency, Q factor, −3 dB bandwidth, impedance at any frequency and the resonance curve.
555 timer calculator
Astable and monostable: frequency, duty cycle, pulse width, the waveform, and which capacitor keeps the resistors sane.
Op-amp gain calculator
Non-inverting, inverting, buffer and difference stages: gain, the noise gain that sets your real bandwidth, the slew-rate ceiling and DC offset.
LED resistor calculator
The series resistor, the catalogue value to buy, the wattage, and the worst-case current your headroom really allows.
PCB trace width calculator
IPC-2221 width for a current, and the check the others skip: whether voltage drop, not heat, sets the width on a long run.
Voltage divider calculator
The output your load actually sees, the source resistance R1∥R2 behind it, the worst case your tolerance allows, and the pair to fit.
Battery life calculator
How long a battery runs a device that sleeps: average current, the ceiling your sleep current sets, and which drain to cut first.
Heatsink calculator
Junction temperature from the whole thermal stack, the heatsink rating your target needs, and the floor no heatsink can beat.
Buck converter calculator
Inductor from the ripple ratio, peak current for saturation, ESR-vs-capacitance ripple split, and a full loss breakdown.
Boost converter calculator
Step-up design with the thing 1/(1−D) hides: a hard gain ceiling, the input current the inductor really carries, and the RHP zero that caps your loop.
Zener diode calculator
The window of series resistors that work at every worst-case corner, the one to buy, the zener rating needed — and when no resistor can work.
L-pad calculator
Tweeter attenuator resistors rounded as a pair, and what the pad does to a tweeter that is not 8 Ω: the load the crossover sees and the level it adds at resonance.
Why these tools
Most engineering calculators online are fifteen-year-old pages buried in ads. These are built the way a tool should be: instant results as you type, correct formulas shown in the open, sensible defaults, dark mode, and links you can share or bookmark with your numbers preserved. More tools ship regularly.