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Kennedy Half Dollar (1964) — ping test & specs

Only the 1964 Kennedy half is 90% silver (12.5 g / 30.6 mm — the classic half planchet). The 1965–1970 issues are 11.5 g 40% silver-clad and 1971+ are copper-nickel; all share the diameter, so weight and the ring are the discriminators.

Opens the free tester with this coin preselected — audio never leaves your device.

Official specifications

Weight12.5 g
Diameter30.6 mm
Thickness2.15 mm
Composition.900 silver (90%)

Source: United States Mint. Coin Pinger checks measured weight and diameter against these values.

Expected resonance range

High confidence*
ModeExpected ringRecommended variance
c0d24.33–5.42 kHz±11.1%
c0d310.06–12.46 kHz±10.7%
c0d417.57–21.77 kHz±10.7%

A genuine Kennedy Half Dollar (1964) rings within these ranges at its c0d2/c0d3/c0d4 vibration modes, fixed by its size and metal. The recommended variance is how far a genuine specimen's ring can sit from each center — built up in quadrature from real manufacturing tolerance and temperature (under 1%), phone-mic capture reproducibility (≈4%), an extra allowance on the fundamental for minting-asymmetry splitting, and a per-metal model-uncertainty term (largest for .9999 gold, whose modulus is least certain). This coin's band is widened further because circulated 90%-silver classics lose mass and edge crispness with wear, spreading their ring. The higher modes also carry a small thick-plate centre correction, since a real coin is not infinitely thin. The high-confidence tag reflects how well-established this metal's constants are: Computed from well-established silver elastic constants and cross-checked against same-size sibling coins. These are guidance bands, not exact values — see the methodology for the exact formula, or calibrate your own coin in the app for a specimen-exact reference and tighten each peak per coin.

* These are computed guidance ranges. Certain your Kennedy Half Dollar (1964) is genuine but it won't match? Send us its ring — we'll dig in and improve the reference.

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How to ping test a Kennedy Half Dollar (1964)

  1. Hold — grip the coin by its center (a nodal point) in a coin ping-test holder so the rim rings freely; a fingertip at the center is a last resort.
  2. Tap — strike the edge with a striker near the microphone.
  3. Read the verdict — MATCH or NO MATCH against the peaks above, plus weight and size checks.

Kennedy Half Dollar (1964) — frequently asked

How much does a Kennedy Half Dollar (1964) weigh?

The official specification is 12.5 g in .900 silver (90%) (source: United States Mint). Coin Pinger's weight check allows ±0.3 g by default. Circulated specimens lose a little mass to wear, so weigh toward the low side of that window.

What size is a Kennedy Half Dollar (1964)?

30.6 mm in diameter and 2.15 mm thick at the rim, per United States Mint. Note the average disc thickness is less than the rim caliper reading — the raised rim and relief concentrate metal at the edge.

What frequency does a genuine Kennedy Half Dollar (1964) ring at?

Its fundamental (c0d2) vibration mode is computed to ring in the 4.33–5.42 kHz range, with higher modes near 10.06–12.46 kHz and 17.57–21.77 kHz. These are first-principles physics computations from the coin's published mass, diameter, and metal — not measurements of sample coins.

Why does my genuine Kennedy Half Dollar (1964) ring slightly off the listed frequencies?

Wear is the biggest factor for the Kennedy Half Dollar (1964): circulated 90%-silver classics lose mass and edge crispness, which spreads the ring across specimens. On top of that, phone-mic capture moves a genuine peak a few percent tap-to-tap (strike point, how you hold it, the mic itself). That's why this reference band is wider than a modern bullion coin's.

Does ping testing damage a Kennedy Half Dollar (1964)?

No — the test needs only a light tap on the edge with a non-marring striker (a wooden pencil or plastic stylus works well), far gentler than normal handling. Hold the coin at its center so the rim can ring freely.

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The physics of the Kennedy Half Dollar (1964) ping

Those 3 peaks aren't random. When you strike the coin it flexes as a free disc in fixed patterns called vibration modes — 0 nodal circles with 2, 3 and 4 nodal diameters, written c0d2 / c0d3 / c0d4. Each pattern rings at one frequency.

Where those frequencies land is set by the coin's geometry and metal. For a thin disc, frequency ∝ (thickness ÷ diameter²) × √(stiffness ÷ density). This Kennedy Half Dollar (1964) spreads 12.5 g of .900 silver (90%) across 30.6 mm — an effective disc thickness of about 1.6 mm once the raised rim and relief are averaged out — which puts its fundamental (c0d2) near 4875 Hz.

An ideal thin disc's modes sit at fixed, geometry-only ratios: 1 : 2.33 : 4.11. A real coin isn't infinitely thin — shear in the metal drags the higher modes slightly below the ideal — so this coin's computed reference lands at 1 : 2.31 : 4.03. Spacing near those ratios is the fingerprint of a struck disc, and Coin Pinger rejects taps that don't fit it (keys, glass, a coin lying on a hard surface).

And it's why a fake can't hide: change the metal and √(E/ρ) changes, so every mode moves. Struck in lead or a plated base metal instead, the ring would land far lower and die out with a dull, short thud — its c0d2 would land near ≈2100 Hz instead of 4875 Hz. Density can fool a scale; the ring can't be faked without the right metal.

We publish this as a High confidence reference. Computed from well-established silver elastic constants and cross-checked against same-size sibling coins.

Free-plate modes per A. W. Leissa, Vibration of Plates, NASA SP-160 (1969, public domain). See how we measure them →