How is fall damage calculated in Minecraft?

How does the game determine how much damage you take? Is there a formula out there that determines how many hearts of damage you take per blocks fallen?

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Solid question! – Dream Lane Dec 29 '10 at 2:24
If anyone is interested in this topic, Zisteau has a great video about how armour and protection enchants effect fall damage youtube.com/watch?v=R0PFQeJsmms – shanodin Apr 21 '14 at 5:40

Fall damage is calculated by calculating the distance fallen (in blocks).

Specifically, Falling Damage =(number of blocks fallen x ½) - 1½.

This means that you can safely drop 3 blocks at once without taking damage. Jumping gives 1½ blocks worth of upward momentum, so if you jump off another block, you can only fall one and a half blocks safely.

Ladders and deep water (at least 3 squares deep as of 1.6) can mitigate this, ladders by cancelling your momentum (and resetting your fall distance) and water because it's water, and generally stops falling damage in any video game that fails to model surface tension. :P

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Things I learned in Half-Life: falling into 3 inches of water after falling 100 feet is perfectly safe. – Nick T Nov 4 '10 at 12:47
@Keaanu Yes, if you have the reflexes of a jungle cat with ninja training. – sjohnston Nov 4 '10 at 14:24
@Keaanu: and if the micraft world was actually miles tall (its 128 meters from bedrock to max build height) – RCIX Nov 4 '10 at 23:17
Just make sure you don't fall onto the ladder. :P (I'm pretty sure that still kills you after a fall . . .) – Kevin Yap Nov 5 '10 at 0:33
@sjohnston There used to be a trick in WoW, if you were a druid, you could shift into bear as you fell and if you targeted and charged an enemy after you got low enough to charge, but before you hit the ground, you'd take no damage (and surprise the holy hell out of someone). To do it right, you had maybe a second, at the very outside. – Satanicpuppy Nov 8 '10 at 21:40

You can make fall safety nets doing that. Say you dig a large shaft and want to get down quickly and safely. you can put a water source block 3 meters/blocks above the ground and put a sign right below it. The floating water will lower, but not reset your speed. So make sure you place enough waterblocks between you and the ground. (3 blocks slows you down enough for practically any height).

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I like it--that would save climbing out of the water. – Loren Pechtel Dec 29 '10 at 18:44