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Belt speed in game inaccurate

Topic starter

I first noticed this when trying to feed five mk2 smelters with a fully saturated line of ore on a mk2 belt.  Five smelters, at 88 items/minute, should need 440 ore per minute; should be able to be fed by a mk2 belt (480 items/min).  In my first test, one of the smelters was occasionally starved; it didn't have enough ore to continuously work, and was paused for a brief amount of time.  Which shouldn't happen.

So I set up a test of the mk2 belts; loaded up a chest with 4 stack inserters (5 per swing), merged together to get a fully saturated mk2 belt.  Lead it to another chest with 4 stack inserters picking everything off the belt; leaving one spot between the two unconnected.  I dropped a belt connecting the two, disconnecting said belt exactly 60 seconds later.  Here are the results:


mk2 test 1: 426 items

mk2 test 2: 428 items

mk2 test 3: 429 items


Even accounting for random loss/gain in placing/deleting a belt segment, ~428 items/minute is far from 480 items/minute; a full 60 items less is a drastic loss. About 89-90% of expected efficiency cannot be explained by just one belt segment with inaccurate timing (plus/minus one second). Belt is 10% slower than in- game metric.  I tested the mk1 belt (240 items/minute); I got 128 items/min each time.. Not as bad as mk2 (95% accurate) but still not the given in-game metric..

As far as I can tell, there's a couple possibilities here:

  1. Could in-game metrics be incorrect?
  2. Are the belts not performing up to the expected metric?
  3. My computer is, well, old, and not as performant as newer systems.. Could lower framerates/engine ticks (as in factorio parlance) be affecting my timing?
    1. although if this were the case, I would have expected the smelter speed to be affected as well, and not seen the starvation I was seeing..

I have some "complicated" setups (my atlantium processing is overengineered, but thats why I play these games), which means I'm going to go over my setup numbers again to make sure I'm getting the throughput I need.

Thoughts on this? Is anyone else seeing this issue?

cyrix Topic starter September 5, 2023 9:17 pm

Attaching my belt speed setup.. the gap in the belt is placed at the start, then removed 60 seconds later. I then count the iron in the chest on the right, the iron in my inventory (from the deleted belt) and anything still being held by stack inserters..

SiyahaS September 7, 2023 8:10 pm

@cyrix I have created my own testing using a single line of 240 segment conveyors. My results:
* Each conveyor segment holds up to two items.
* Conveyor Belt Mk1's item speed is actually 3.33 items/s not 4 items/s.

Here is a link to recording of my test https://youtu.be/-iiC0U2Dm_8