Coin Pinger
Acoustic bullion authentication — free, private, on-device
Test gold & silver coins by their ring
Coin Pinger is a free acoustic ping test that spots fake gold and silver coins. A real coin rings like a bell at frequencies fixed by its size and metal. Pick one of a library of preset coin references — or calibrate your own genuine coin — and any coin of that type must reproduce its acoustic fingerprint to pass.
Works in your browser · nothing to sign up for · audio never leaves your device
Grounded in physics
Calculated, not guessed
How Coin Pinger separates itself from other coin ping testing apps: it computes each coin from first-principles physics first, while building a library of real-world sample values for a second, corroborating check — and more accurate reads in the future. The math leads; the data will confirm.
Physics first, samples second
A coin's expected ring is computed from its size and metal through the free circular-plate equations — that calculation is the primary check. As opt-in samples accumulate, they become a second, corroborating indicator: the math leads, real-world data confirms.
f = (λ²/2πa²)·√(D/ρh)Measurement, not AI
We measure the actual sound — its peak frequencies with a high-resolution 32,768-point FFT, plus how fast the ring fades. No neural network making a judgment call; just a transparent number you can check.
Open, not black box
Every input, coefficient and tolerance is visible and adjustable. Enter a diameter for any 1 oz .999 silver round, or calibrate your own coin — same physics, your parameters.
Three steps
How the coin ping test works
From tap to verdict in seconds — no equipment beyond your microphone.
Pick a reference
Choose from our preset coins — or hold a known-genuine coin in a coin ping-test holder so it rings freely, tap its edge, and save its ring as your own named reference.
Tap the coin
Tap the coin in question near your microphone. Its ring must match every reference peak within tolerance — wrong metal, wrong pitch.
Read the verdict
A clear MATCH or NO MATCH, with ring-decay analysis plus optional weight and dimension checks against official mint specs.
What's inside
Everything you need to spot a fake
Six independent checks — resonance, decay, weight, and dimensions — that set us above all the rest.
Resonance fingerprint
Detects the coin's c0d2/c0d3/c0d4 vibration modes with sub-Hz precision — the same physics used by professional acoustic verifiers.Preset coin library
Gold and silver coins with recommended resonance ranges — typical bands, not exact values — start testing without owning a genuine reference.Any silver round
No preset for your coin? Enter the diameter and we compute the expected ring for any 1 oz .999 silver round — not just the named coins.Ring decay analysis
Solid precious metal rings long; other alloys die out fast. Decay rate is compared against your reference.Adjustable tolerance
Tune the match window per coin — tighten it for strict discrimination or loosen it for worn pieces. Sensible per-mode defaults out of the box.Rejects non-coin sounds
Keys, glasses, and taps that don't ring like a free disc are filtered out before any verdict, so a random ding can't read as a match.Weight & dimensions
Preset tables of official mint weights and sizes for common bullion, with sensible tolerances.Share references
Send a calibrated coin as a link or JSON file — friends can test against your verified fingerprint, tolerances and all.Private by design
Your coin audio and reference library never leave your device. No accounts, no uploads. We measure only anonymous, aggregate traffic to improve the product.Why Coin Pinger
The ping app that can say NO
Deeper measurement and controls you can tune — so each verdict is one you can trust.
A clear NO MATCH verdict
Every test ends in a straight answer — a clear MATCH or NO MATCH, so you always know where you stand.
Measures the whole ring
Pitch, ring decay, sustain, and pitch stability are all checked — so a dull or damped fake can't hide behind one lucky frequency.
Sub-Hz precision
The largest FFT the browser allows, plus interpolation, so the match band is set by the coin's real variation — not coarse frequency bins. See how →
Presets, calibration & any silver round
Test our preset coins, fingerprint a genuine coin you own, or check any 1 oz .999 silver round by its diameter.
Tune it per coin
Adjust each peak's match band from 0.5% to 20% for a specimen-exact fit — tighter for strict discrimination, wider for worn pieces.
Free & open source
No account, no monthly limits, nothing to install. MIT-licensed, and your audio never leaves your device.
Coin library
Preset coin references
Every preset coin ships with a recommended resonance range (a typical band, not an exact value), plus official weight and diameter. Generic 1 oz .999 silver rounds are covered too — just enter the diameter. Don't see yours? Calibrate any solid coin ≥25 mm yourself in seconds.
Most popular
Silver
Gold
Fractional sizes (1/2 · 1/4 · 1/10 oz)
* Confidence reflects our first-principles mathematical model — references are computed from acoustic physics, not a measured database, so they carry more uncertainty where a metal's constants are less certain. As people opt in to share anonymous results, the growing sample set lets us tighten them toward measured accuracy. Coin not listed? Compute it with the resonance calculator.
The physics
Why ping-test a coin?
Solid silver or gold rings like a bell — at exact pitches fixed by its size and its metal's density and stiffness — and the ring sustains, decaying slowly and cleanly.
Copper, lead, tungsten, or plated cores have the wrong density and stiffness — the ring lands at the wrong pitch, sounds dull, and dies out fast.
Because resonance is set by both the coin's geometry and its metal, reproducing a genuine coin's full set of ring frequencies is very hard to fake. Coin Pinger turns your phone's microphone into an acoustic verifier that measures those frequencies and their decay — a fast, non-destructive first check before you buy or sell.
Questions
Frequently asked questions
What is the coin ping test?
The ping test authenticates a coin by the sound it makes when struck. A genuine gold or silver coin rings at resonance frequencies fixed by its exact size and its metal's density and stiffness. A counterfeit made of the wrong metal rings at different frequencies and its ring dies out faster, so comparing the sound to a known-genuine coin reveals fakes.
Can it detect fake silver and gold coins?
Yes. It measures resonance peaks and ring decay against a preset reference or one you calibrate from a coin you trust, and can also check weight and diameter against official mint specs. Treat it as one strong signal — pair it with weight and dimension checks for confidence.
Which coins does it work with?
It ships with a library of preset references — Eagles, Maples, Britannias, Krugerrands, Philharmonics, Kangaroos, Pandas, Libertads, Morgan and Peace dollars, Sovereigns, and more. And you can calibrate any solid bullion or collector coin roughly 25 mm or larger yourself.
Do I need special equipment?
No — just a phone or computer with a microphone. Hold the coin in a coin ping-test holder (a fingertip works as a last resort), tap its edge near the mic, and the app analyzes the ring. A cheap scale and calipers are optional for the weight and size checks.
Is my audio or data uploaded?
Audio, never. Microphone audio is analyzed live in your browser and is never recorded, stored, or sent, and your own calibrated coin library stays on-device. If you leave "Help improve Coin Pinger" on, the app shares anonymous results from preset-coin tests — the measured numbers only, never audio — so we can tighten the references for everyone; turn it off anytime in the app. We also use Google Analytics for aggregate, anonymous traffic only — never to identify or track anyone. See our privacy policy.
Is Coin Pinger free?
Yes, completely free, in any modern browser. You can also install it to your home screen and use it offline.
Get started
Ready to check your coins?
Free, private, and listening in seconds — right in your browser.