This is a guide for blood and health regeneration in DayZ as of version 0.34.115106. Take note that, due to the nature of DayZ, more drastic changes can be expected in the game, and so the information here will likely be changed again in a few months.
Injury is an unavoidable eventuality in Dayz. Survival means recovering lost blood and health by staying hydrated. However, regeneration comes in many forms, so it pays to be acquainted.
Slow Blood Regeneration costs 2000 Energy and higher than 1500 Water. Blood comes back at the rate of 1 blood per second. Minor blood loss is easy to recover in an extended period of time. This does not lead to healthy status, but there will be indicators to show regeneration happening. As long as your indicators show you are not thirsty, and that you are being energized, slow blood regeneration is ongoing.
Full Blood Regeneration costs 4000 Energy and 2500 Water. You regenerate at 3 blood per second. Within 15 minutes, you should have regenerated 1000 blood. Your status indicators will indicated you are hydrated and energized.
Health Regeneration costs 4000 Energy and 2500 Water. The good news is, this is what you get after you go through Full Blood Regeneration. The bad news is, you have to earn the necessary requirements for full blood regenerations, and fill up your blood, before you can regenerate health. You will get a healing status indicator, which will switch to healthy when you are full.
You should know as well that you can be at full health, but suffering from loss of blood. In this scenario, your health is full, but the indicator will show you are healing. You regenerate 1000 health in 15 minutes.
These status indicators have some glitches. If you are worried about how those glitches appear, you can learn from the source here.
