Seismo: Vibration Meter

Turn your iPhone into a real-time vibration meter: live waveform, FFT spectrum, RPM, ISO severity, and fault diagnosis. 100% on-device. Free, no ads.

Seismo turns your iPhone into a real-time mechanical-vibration instrument.

Point it at a wobbling washing machine, a droning HVAC unit, an idling engine, a spinning fan, a workbench, or a floor — and read what's actually happening. A living seismograph trace writes itself across an oscilloscope grid while a big, monospaced readout locks onto the dominant frequency. It's calm, exact, and built like a precision instrument, not a toy.

No account. No ads. No subscription. Everything runs on-device and offline.

— What it measures —

• Live waveform — a continuously drawn seismograph trace on a fine oscilloscope grid, with a glowing leading dot that snaps when it locks onto a stable frequency. • Dominant frequency & RPM — the giant hero number, in Hz or RPM. • Amplitude & severity — RMS velocity (mm/s) graded on an ISO-10816-style green→amber→red scale (Zones A–D), plus peak g and crest factor. • Frequency spectrum — a live FFT bar chart from 0–50 Hz with a tagged peak and 1×/2×/3× harmonic cursors, in linear or log scale. Touch the chart to inspect any frequency — the cursor snaps to nearby peaks. • Fault diagnosis — a guided timed capture produces a plain-English verdict: imbalance, misalignment, looseness, or bearing wear, with a confidence level and a short explanation of why.

— How it works —

Seismo reads the iPhone's built-in motion sensors (CoreMotion accelerometer and gyroscope) and runs the signal through a fast Fourier transform (Apple's Accelerate framework). It integrates acceleration to velocity the same way industrial vibration analyzers do, then reads the harmonic signature of the spectrum to suggest a likely fault. Rest the phone flat and firm against the machine, tap start, and watch the numbers settle.

— Honest about accuracy —

This is a feature, not fine print. Phone accelerometers sample at about 100 Hz, so Seismo analyzes the 0–50 Hz band — the range where most machine faults live — and they are not lab-calibrated. That means Seismo is excellent for what most people actually need: relative comparison, dominant-frequency identification, trend tracking, and fast triage. The method (ISO velocity integration and harmonic-signature analysis) is industry-correct; the absolute numbers are device-relative. Use it to answer "is this worse than last week?" and "what is this vibration?" — not as a certified, safety-critical, or warranty-grade instrument.

— Built for —

DIYers, appliance / HVAC / auto repair, machinists and woodworkers, facilities and maintenance teams, audio installers, and anyone curious whether a vibration is normal — and what it is.

— Also includes —

• Records — save measurements per machine, watch trends, export to CSV/PDF. • Guide — what frequencies mean, ISO severity explained, how to mount the phone, and an honest note on accuracy. • Shortcuts & widgets — start a measurement via Siri / App Intents; see a machine's last reading or severity on the Home Screen. • Units your way — g or m/s²; mm/s or in/s; Hz or RPM. • Machine-size severity — ISO 10816-1 zone limits for four machine classes, from appliances to large industrial units. • Light and dark "CRT graphite" themes, haptic peak-lock, and full offline operation.

Private by design. Motion data is analyzed entirely on your device and never leaves your phone. No data collection, no tracking, no analytics, no network calls. App Store privacy label: Data Not Collected.