According to this external Sandhi rule, vowels as final sounds merge with the next word if it also starts with a vowel. If the word starts with a consonant, there is no merger.

Sanskrit Sandhi

Identical vowels - lengthening

Two identical vowels melt to form one single long vowel (spelled together).

final sound initial sound Sandhi
-a/ā a/ā- -ā-
-i/ī i/ī- -ī-
-u/ū u/ū- -ū-

Umlaut formation with a/ā as a leading vowel

a/ā forms umlauts with the succeeding vowel in accordance with vowel increase, Guṇa and Vṛddhi formation (spelled together).

final sound initial sound Sandhi
-a/ā i/ī- -e-
-a/ā u/ū- -o-
-a/ā ṛ/ṝ- -ar-
-a/ā ḷ/ḹ- -al-
-a/ā e- -ai-
-a/ā ai- -ai-
-a/ā o- -au-
-a/ā au- -au-

Formation of semivowels with i/u/ṛ/ḷ

i/u/ṛ/ḷ before are vowel turn into the corresponding consonant/semivowel (spelled together).

final sound initial sound Sandhi
-i/ī Vokal -y-vowel-
-u/ū Vokal -v-vowel-
-ṛ/ṝ Vokal -r-vowel-
-ḷ/ḹ Vokal -l-vowel-

Umlauts in front of vowels are dissolved

  • "e", "ai" and "o" before vowels (except "e" and "o" before "a") lose their umlaut component (spelled separately, together for compound words).
  • "e" and "o" before "a" lose the initial a (spelled together).
final sound initial sound Sandhi
-e a- -e_'
-e not-a-vowel- -a_not-a-vowel
-o a- -o_'
-o not-a-vowel- -a_not-a-vowel
-ai vowel -ā_vowel
-au vowel -āv-vowel

Vowels in front of consonants - no change

Vowels preceeding consonants remain unchanged. It is only before "ch" that a "c" is inserted (spelled separately, together for compound words).

Auslaut Anlaut Sandhi
…Vokal Nicht-"ch"-Konsonant… …Vokal_Nicht-"ch"-Konsonant…
…Vokal ch… …Vokal_cch…


"ī"/"ū" and "e" as final sounds of dual forms remain unchanged, i.e. they are not affected by the rule described above (spelled separately).

In table form

For all of you who like tables and charts - the same information once again in the form of a neat and concise table.

a/ā i/ī(1) u/ū(1) ṛ (ṝ) (ḷ/ḹ) e(1) ai o au start
ā- y-a v-a r-a l-a e_' ā_a o_ āv-a a
ā- y-ā v-ā r-ā l-ā a_ā ā_ā a_ā āv-ā ā
e- ī- v-i r-i l-i a_i ā_i a_i āv-i i
e- ī- v-ī r-ī l-ī a_ī ā_ī a_ī āv-ī ī
o- y-u ū- r-u l-u a_u ā_u a_u āv-u u
o- y-ū ū- r-ū l-ū a_ū ā_ū a_ū āv-ū ū
a-r y-ṛ/ṝ v-ṛ/ṝ ṝ- l-ṛ/ṝ a_ṛ/ṝ ā_ṛ/ṝ a_ṛ/ṝ āv-ṛ/ṝ ṛ(ṝ)
a-l y-ḷ/ḹ v-ḷ/ḹ r-ḷ/ḹ a_ḷ/ḹ ā_ḷ/ḹ a_ḷ/ḹ āv-ḷ/ḹ (ḷ/ḹ)
ai- y-e v-e r-e l-e a_e ā_e a_e āv-e e
ai- y-ai v-ai r-ai l-ai a_ai ā_ai a_ai āv-ai ai
au- y-o v-o r-o l-o a_o ā_o a_o āv-o o
au- y-au v-au r-au l-au a_au ā_au a_au āv-au au
a-/ā_X i-/ī_X u/ū_X ṛ/ṝ_X ḷ/ḹ_X e_X ai_X o_X u_X not "ch" consonant
a-/ā_cch i-/ī_cch u/ū_cch ṛ/ṝ_cch ḷ/ḹ_cch e_cch ai_cch o_cch u_cch ch

Exception: "ī", "ū" and "e" as the final sounds of dual forms do not change, also in front of a vowel as the initial sound of the following word. This means that the rule described above does not apply and they remain unchanged (including the separate spelling).