The Abjad numerals, also called Hisab al-Jummal (Arabic: حِسَاب ٱلْجُمَّل, ḥisāb al-jummal), are a decimal alphabetic numeral system/alphanumeric code, in which the 28 letters of the Arabic alphabet are assigned numerical values. They have been used in the Arabic-speaking world since before the eighth century when positional Arabic numerals were adopted. In modern Arabic, the word ʾabjadīyah (أَبْجَدِيَّة) means 'alphabet' in general.

In the Abjad system, the first letter of the Arabic alphabet, ʾalif, is used to represent 1; the second letter, bāʾ, 2, up to 9. Letters then represent the first nine intervals of 10s and those of the 100s: yāʾ for 10, kāf for 20, qāf for 100, ending with 1000.

The word ʾabjad (أبجد) itself derives from the first four letters (A-B-G-D) of the Semitic alphabet, including the Aramaic alphabet, Hebrew alphabet, Phoenician alphabet, and other scripts for Semitic languages. These alphabets contained only 22 letters, stopping at taw, numerically equivalent to 400. The Arabic Abjad system continues at this point with letters not found in other alphabets: thāʾ = 500, khāʾ = 600, dhāl = 700, etc. Abjad numerals in Arabic are similar to the alphanumeric codes of Hebrew gematria and Greek isopsephy.

The Abjad order of the Arabic alphabet has two slightly different variants. The Arabic abjad order is not a simple historical continuation of the earlier north Semitic alphabetic order, since it has a position corresponding to the Aramaic letter samekh / semkat ס, yet no letter of the Arabic alphabet historically derives from that letter.

In the most common Mashriqi abjad sequence, loss of samekh was compensated for by the split of shin ש into two independent Arabic letters, ش (shīn) and ﺱ (sīn), which moved up to take the place of samekh.

The Mashriqi (common) abjad sequence, read from right to left, is:

This is commonly vocalized as follows:

Another vocalization is: