Bigger Stacks is the second upgrade in Bloons TD 4 and the first upgrade in the Path 1 in Bloons TD 5 for the Spike Factory. It allows the Spike Factory to create double sized spike piles, each pile being able to pop 10 bloons instead of 5 per pile.

In BTD6, this upgrade returns. The power of Bigger Stacks tends to be situational now, since purchasing Permaspike will not actually double the number of spikes per pile as typically expected of other upgrades. However, all other upgrades bought in combination with this upgrade (except Spiked Balls and subsequent upgrades) will grant a steady 10 spikes per pile. It costs $600 on Medium.




  • With Tack Awesomizer activated, the piles of spikes the factory produces will have 20 spikes in it.
  • In BTD6, the Spike Factory gains a red larger spout instead of its body becoming red.
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