What is the fatal height for Diamond Prot IV armor?

I've having a very hard time with the math, and it doesn't look like anyone has made a calculator yet, so is it possible to explain the max height on max health before a fatal fall occurs with a full set of diamond Protection IV armor?

As an extra question, can you explain how adding Feather Falling would or would not increase that? Thank you very much.

The reason for this is the server I'm on offers flying in survival as a perk, but sometimes crashes, causing flying to turn off on login. I'd trying to determine the safe distance I can fly without splatting in case of a crash.

I see the base is 23 blocks = fatal w/o armor.

Solution 1:

Unfortunately it is difficult to give a safe falling height as the % reduction from enchantments is random. Normal armor offers no protection against falling damage. Only the relevant enchantments- protection and feather fall- reduce falling damage.

The reduction from enchantments is based on the Enchantment Protection Factor (EPF) of any relevant enchantments. The EPF of an enchantment is based on the level of the enchantment and the type- protection enchantments have a lower epf than more specific protections such as feather fall; they make up for it by working against anything.

The EPF of Prot IV is 5 and the EPF of Feather IV is 18. The cap is 25, which can be achieved in various ways.

Minecraft then multiplies this by a random value between 1 and 2, caps it at 40, then multiplies this by 2. This value is the percentage of the damage prevented by the enchantments.

At the EPF cap, you will mitigate between 50% and 80% of incoming fall damage (mitigating 80% almost half the time).

Assuming a worst case scenario where you only prevent half the damage, you would be able to survive 38 half-hearts of damage - a fall of 41 blocks. In the best case scenario, mitigating 80% of the damage, you could survive 95 damage or 98 blocks.