Three gunpowder is not three times one gunpowder — it is 1.67×
A rocket's boost is 10 × (2 + flight duration) ticks, and that free +2 is why tripling the gunpowder only adds two thirds more distance. The full table, in blocks.
Firework rockets take one, two or three gunpowder, and the obvious reading is that a three-gunpowder rocket flies three times as far. It does not. The boost formula has a constant in it, and the constant is doing most of the work at the low end.
The formula
boost ticks = 10 × (2 + flight duration)
speed = 33.5 blocks/second at level flightFlight duration is the gunpowder count, 1 to 3. The + 2 is not proportional to anything you paid for — every rocket gets it.
What that produces
| gunpowder | boost ticks | seconds | blocks at 33.5 b/s |
|---|---|---|---|
| 1 | 30 | 1.5 | 50.25 |
| 2 | 40 | 2.0 | 67.00 |
| 3 | 50 | 2.5 | 83.75 |
Three gunpowder buys 83.75 blocks against one gunpowder's 50.25 — a factor of 1.67, not 3. Each extra gunpowder adds a flat 16.75 blocks, so the increment is constant while the percentage keeps shrinking: +33% for the second, then +25% for the third.
Which rocket to craft depends on what you are short of
The two resources pull in opposite directions, and both readings are correct:
Blocks per gunpowder — this favours the cheap rocket:
| gunpowder | blocks per gunpowder |
|---|---|
| 1 | 50.25 |
| 2 | 33.50 |
| 3 | 27.92 |
A one-gunpowder rocket is 1.8× as gunpowder-efficient as a three. If gunpowder is your bottleneck — no creeper farm, scraping powder from wandering trader trades — craft the small ones and carry more of them.
Blocks per inventory slot — this favours the expensive one. A full stack of 64:
| gunpowder | blocks per stack of 64 |
|---|---|
| 1 | 3,216 |
| 2 | 4,288 |
| 3 | 5,360 |
The same 64 slots carry 2,144 more blocks of flight as three-gunpowder rockets. For a long haul where inventory space is the real constraint, that is the version to bring.
So the rule is not "always craft threes". It is: gunpowder-limited, craft ones; slot-limited, craft threes. Most players building a rocket farm are eventually slot-limited, which is why threes are the usual advice — but it is advice about your inventory, not about the rockets.
The 33.5 is level flight only
That speed is sustained horizontal flight. It is not the speed you reach diving, and it is not what you average if you are climbing. The distances above are therefore a planning floor for a flat route and an underestimate for a dive-and-glide run.
The stack figures also assume the rockets are fired back-to-back — each one lit as the previous boost ends. That is the model the planner uses, and it is the case the numbers describe; firing them in overlapping bursts is a different calculation and not one these figures cover.