Now we are going to talk about the things that have not occurred yet. Such sentences are called future tense. In Sanskrit there are two types of future tense, right now we are going to learn the most common one, hence the name ordinary future tense. Let us take a look at some of the examples.

गम् → गमिष्यामि
gam →gamishyami
Go → I will go.

मन् → मंस्ये
mam → mamsye
think → I will think

जि → जेष्यन्ति
ji → jasyanti
conquer → They will conquer

So how does future stem is produced?

In order to produce a future stem, the verb root ha to be strengthened to the medium level and then sya has to be attached.
For instance;

ष् → भाषित्वा, भाषिष्य
bhāṣ → bhāṣitvā, bhāṣiṣya
Speak → having spoken, will speak

मन् → मत्वा, मंस्य
man → matvā, maṃsya
Think → having thought, will think

You can also observe one fact regarding Sanskrit here before every suffix there is I vowel present.  For example; itva , isya.

Whereas, in the case of gam it’s different.

गम् → गत्वा
gam → gatvā
go → having gone
The gerund uses the weakest form of the verb root; gam becomes ga.

गम् → गमिष्य
gam → gamiṣya
go → will go

Lastly, when the root ends with a or o, it usually connects itself with the I vowel. For example:

भू → भो → भविष्य          bhū → bho → bhaviṣya           will become

कृ → कर् → करिष्य        kṛ → kar → kariṣya                  will do

जि → जे → जेष्य              ji → je → jeṣya                         will conquer

However, there are some exceptions.

दृश् → द्रश् → द्रश्स्य → द्रक्ष्य
dṛś → draś → draśsya → drakṣya