FlickerSpec: LED Flicker Test

Your LEDs shouldn't be giving you headaches. FlickerSpec turns your phone into a flicker meter, measures them at 240 frames per second, and compares what it finds against published flicker limits.

Built for engineers, lighting designers, facility managers, and anyone tracking down eye strain under LEDs.


WHAT YOU MEASURE

Quick Measurement (free, unlimited)
Live readout:
• Dominant flicker frequency in Hz
• Percent Flicker (modulation depth) and Flicker Index
• Signal-to-noise ratio and confidence rating
• Live luminance waveform and FFT spectrum
• Achieved frame rate

3-Minute PstLM Measurement (Pro)
A tripod capture for documenting low-frequency flicker:
• Short-Term Flicker Severity (PstLM) per IEC TR 61547-1:2015, for flicker up to 90 Hz
• Compared against the PstLM ≤ 1.0 limit cited by EU Ecodesign 2019/2020 (PstLM only; Ecodesign
also needs SVM, beyond FlickerSpec's 240 fps phone-camera pipeline)
• 8x oversampled LM flickermeter checked against all five IEC Table A.1 vectors
• Camera-based measurement aid, not an accredited instrument or certified result


THE VERDICT

FlickerSpec applies IEEE 1789-2015 Recommended Practice 1, the low-risk level: modulation must stay
under 0.025 x frequency below 90 Hz, and under 0.08 x frequency from 90 Hz to 1250 Hz, above which
flicker is unrestricted. A custom percent-flicker threshold is also available and applies to the
badge, the saved record and the PDF. The verdict has three states: FAIL when the measured depth
exceeds the limit, PASS when the capture and framing support it, and Can't confirm when they do not.


DOCUMENTATION AND REPORTS

Save measurements to sessions with location label, fixture photo, GPS and notes. Export
single-measurement or session-summary PDFs, or CSV. Reports carry your company header, the verdict
with the standard and threshold behind it, real measurement uncertainty, the FFT spectrum, and the
calibration certificate reference. FlickerSpec is a screening and documentation aid, not an
accredited laboratory instrument; whether a report satisfies a particular surveyor or regulator is
their determination.


CALIBRATION IS FREE

Before measuring, point your phone at the free companion calibration web app on any monitor.
FlickerSpec verifies its frequency accuracy against the known signal and issues a timestamped
certificate valid for 30 days.


WHAT IT CAN AND CANNOT SEE

A 240 fps camera has limits, and we state them. The method is designed for 50 Hz mains regions:
• 50 and 100 Hz (50 Hz mains) — frequency and modulation depth
• 60 and 120 Hz (60 Hz mains, e.g. North America) — the dominant frequency may still be
identifiable, but depth and verdict are conditional because 240 fps is an exact multiple of
both. The app reports Can't confirm when it cannot sample the whole cycle.
• Above 120 Hz, including PWM dimmers and kHz drivers — outside camera bandwidth
Depth also depends on framing: fill the region of interest with the light, or treat it as a lower
bound.


FREE VS PRO

Free, no account:
• Unlimited Quick Measurements with every raw metric, live waveform and FFT spectrum
• Calibration and certificate generation

Pro — $49.99 one-time, no subscription:
• IEEE 1789-2015 risk indication (PASS / FAIL / Can't confirm)
• 3-Minute PstLM Measurement with a PstLM threshold comparison
• Measurement logging with GPS, photos, and location labels
• Single-measurement and session-summary PDF reports, CSV export
• Calibration certificate document display
• Report header with your company name and logo


TECHNICAL SPECIFICATIONS

• 240 fps constrained high-speed Camera2 capture, ITU-R BT.709 luminance, exposure and white
balance locked during measurement
• Standards: IEEE 1789-2015 Recommended Practice 1, IEC TR 61547-1:2015 Annex A, IES TM-39-25,
Commission Regulation (EU) 2019/2020
• On-device storage only, no cloud, no account, no tracking


Privacy Policy: https://flickerspec.slick-engineering.workers.dev/privacy

Recent changes:
Improved measurement interpretation and documentation:

• IEEE 1789 results now distinguish PASS, FAIL and Can't confirm when capture coverage or framing cannot support a pass.
• Calibration now includes 144 Hz, 165 Hz and 240 Hz displays.
• Guidance and reports now explain 60/120 Hz camera-depth limitations and PstLM scope more precisely.
• Reliability and report-formatting fixes.