GPU computing: how much VRAM do I need for mini batch gradient descent?
Generally memory cost increases linearly while mini-batch size increases. If batch size 32 costs you 2GB memory, then batch size 64 will cost you 4GB memory.

In practice, deep learning framework(for instance, keras) will load the entire full-batch into your memory, thus you cannot observe apparent memory increment or decrement during mini-batch tuning.

References

https://github.com/fchollet/keras/issues/146