Until what depth should you equalize your freediving mask?

Mask equalization can be a critical factor in reaching new depths:
Systematic mask equalization will cause you to lose a significant amount of air that will no longer be available to your ears. While refusing to equalize the mask will result in a mask squeeze and the zombie eyes that go with it.

The challenge is to determine at what depth the last equalization of the mask will take place to ensure that the maximum amount of air is available for your ears while excluding the risk of injury at the targeted depth.

To do this, we can perform a simple calculation…
First of all, you will have to make a dive in which you will keep your nose pinched as soon from the surface and never release your fingers (so do not equalize the mask at all). Then stop at the depth at which your mask becomes uncomfortable and remember the depth.

Once at the surface, convert this depth into pressure. For example, if at 10m the mask becomes too oppressive, note 2 bars of pressure. Since the surface pressure is 1 bar, this means that with this mask you can withstand a pressure multiplication by 2 without having to equalize it.

You then need to know the depth you are aiming for in your training cycle and convert this depth into pressure. For example, 5 bars if you are aiming for a depth of 40m.

Then divide these two values. In our case: 5bars / 2 = 2.5 bars
Finally, convert the result into depth: 15m

In our case, this means that if I stop equalizing my mask at 15m, I can continue my descent to 40m without risk of injury while ensuring maximum air supply for my ears.

The interest of doing this exercise at the beginning of the training cycle is to be able to quickly get into a habit and avoid having to make last-minute changes that are likely to penalize you when the goal is getting closer.