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Do I Need a Spare Ball? Here's What 38,469 Real Throws Say

We went through every first ball ever recorded in BowlSense and counted where the pins actually go. The corner pins are both the most common leave and the hardest to convert — and that changes the answer to the most-argued question in bowling.

"Do I really need a spare ball?" It's the second most argued question in bowling, right behind which strike ball to buy. And the usual answer is a shrug: "depends on your game." We can do better than that. BowlSense has 38,469 recorded first balls from real bowlers — every pin, every frame, logged as it happened. So instead of guessing, we counted. Here's what the pins actually did.

38,469 First balls counted 3,023 10 pin leaves 68.5% 10 pins converted 5,339 Games analysed The 10 pin is the most common thing that happens to you Out of every first ball in our data, the single most frequent outcome after a strike is a 10 pin left standing. It happened 3,023 times — that's 7.9% of every first ball , or roughly one 10 pin every other game.

The next most common single pin — the 4 pin — shows up 1,186 times. The 10 pin appears two and a half times more often than any other single pin. | Leave | Times left | Converted | | | | | | 10 pin | 3,023 | 68.5% | | 4 pin | 1,186 | 82.7% | | 7 pin | 1,120 | 68.8% | | 6 10 | 1,098 | 67.3% | | 9 pin | 835 | 84.0% | | 3 6 10 | 796 | 61.9% | | 6 pin | 718 | 76.9% | | 2 pin | 532 | 88.

2% | If you're left handed, swap the 10 for the 7 — it's the mirror image shot, and as you'll see in a second, it's just as hard. The part that actually settles the argument Look down the conversion column again. Every single pin in the list converts somewhere between 76% and 88% — except two of them. The 7 pin: 68.8%. The 10 pin: 68.5%. Nearly identical, and both well below everything else.

That's the whole thing in one line: The corner paradox The corner pins are simultaneously the most common leave and the hardest to convert. Corner pins make up 48% of every single pin leave in our data (4,143 of 8,709) and convert at 68.6%. Every other single pin converts at 82.3%. Browse the catalog That 13.7 point gap is the cost of the corner.

Applied to the 3,023 ten pins in our data, closing it would be worth about 400 extra spares — from bowlers who were otherwise perfectly capable of picking up a single pin. It's not that these bowlers can't shoot spares. They convert the 2 pin 88% of the time. It's that the corner pin is a different shot, and most people are trying to make it with the wrong tool.

Why a hooking ball is the wrong tool for a corner pin A reactive strike ball is built to grip the lane and change direction. That's exactly what you want going at the pocket, and exactly what you don't want going at a single pin sitting in the corner. Two things go wrong: The margin is tiny.

To hit a 10 pin with a ball that hooks, you're throwing across the lane and relying on the ball to stop hooking at the right moment. Miss the friction by a board and the ball either crosses in front of the pin or never gets there. The lane keeps changing. Oil moves during a session. A hooking ball's path to the corner moves with it, so the shot that worked in frame 3 doesn't work in frame 8.

A ball that doesn't hook goes where you aim it in the first frame and the last. A plastic spare ball removes the variable. You aim at the pin, you throw it straight, the lane condition barely matters. So — do you need one? Honestly? If you bowl league and you're leaving corner pins, yes. The data above is about as clear as community data gets.

But here's the fair version of the argument, because there are people who genuinely don't need one: Buy one if You hook the ball The more your strike ball moves, the worse it is at corner pins. Higher rev rate, more surface, stronger cover — bigger the case. Maybe skip it if You already throw straight If your strike ball is a mild plastic or entry level reactive that barely moves, you already own a spare ball.