Jump Coin

Hold your phone and jump — the accelerometer detects it and chimes

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Hold your phone and jump

Grip your phone firmly and jump in place! The device's accelerometer detects the jump and plays a retro game-style coin chime. The more you jump, the more coins you collect.

Time limit

※ Play in a safe, clear space, grip your phone firmly, and take care not to throw or drop it.

Spotting a jump: a drop to almost zero, then a spike

Jump Coin watches the overall strength of what your phone's accelerometer measures (the combined value of all three axes, gravity included). Held still, that's about 9.8 m/s² — just gravity. Once you leave the ground, the phone is falling along with you and the reading drops close to zero. On landing, the impact sends it shooting up.

Concretely: two readings in a row below 4.0 mean "in the air," and a reading above 14 while in the air means "landed." If the time in the air was between 0.08 and 2 seconds, it counts as one jump, and the next 0.25 seconds are ignored so the landing jolt isn't counted twice. Simply shaking the phone hardly ever keeps the reading near zero long enough, which is why it's rarely mistaken for a jump.

The height is an estimate from airtime

Height is calculated as h = g × t² ÷ 8, where t is the airtime and g is 9.8 — assuming half the time is spent rising and half falling. An airtime of 0.4 seconds gives about 20 cm; 0.5 seconds gives about 31 cm.

Because the phone wobbles in your hand, it isn't truly weightless the whole time, so the number tends to read low and vary from jump to jump. If you're comparing with family or friends, hold the phone the same way for a fair contest.

Ways to play, and safety rules

Pick a time limit of none, 10 s, 30 s or 1 min. With a limit, the countdown starts when you collect the first coin, so you can get a firm grip before you start jumping.

What's recorded: your best airtime (your estimated best height) and your most coins for each of 10 s, 30 s and 1 min. Both stay in this device's browser and are never sent anywhere
Confetti every 10 coins, and a short vibration per coin on devices that support it
Little hands slip easily: use a wrist strap, let an adult hold the phone with them, and jump only where there's nothing and nobody nearby

When the sensor isn't available

On iPhone and iPad, pressing Start asks for motion-sensor permission. If you declined, allow it in Settings and reload the page.

On PCs without a sensor, or devices that grant permission but send no readings, use the "Tap for coin sound" button instead. Taps can't measure height, so your height record won't change.

Sensor readings are used on the device only, to decide whether you jumped. The coin sound is synthesized on the spot, so no audio files are downloaded either.

Troubleshooting

Q. Coins went up even though I didn't jump.: A. Dropping the phone onto a table, or swinging it down hard and stopping, can look like "airborne, then landing." Press Stop whenever you're not jumping.
Q. There's no sound.: A. Check the silent switch and the volume. Sound is enabled when you press Start, so always begin with that button.
Q. Can it count jump-rope skips?: A. Jumping in place is counted, but we don't recommend swinging a rope while gripping your phone — it's too easy to drop.