At a glance:

The angula and hasta are the main units of measurement. Six types of measurement are mentioned. Measurement of height or length, breadth, width or circumference, along plumblines, of thickness and inter space.

The ancients used the angula (3/4″) for the measurement of idols and the hasta (24 angulas or 18″) or cubit for measurement of residential buildings, temples and palaces. The hasta was also used to measure conveyances (yana), couches (sayana), etc.

Six types of measurements are described.
Mana          Measurement of height or length
Pramdna      Measurement of breadth
Parimdna     Measurement of width or circumference
Lambamdna Measurement along plumblines
Unmdna      Measurement of thickness
Upamdna    Measurement of inter space.

The classical works also speak of the Ghanamana (exterior measurement) and aghanamana (interior measurement).

Mdna is also used generally to mean measurement.

We also have adimana which means primary measurement or comparative measurement.

Talamdna is the sculptural measurement. Here the length of the face from the top of the head is the unit. This length can also be taken as the distance between the tip of the middle finger and the top of the thumb of a fully stretched palm.

Manasara mentions the following:

1  paramanu  1 atom
8 paramanu   1 ratha dhooli (molecule)
8 ratha Dhooli   1 vaalagna (hair end)
8 valagna    1 liksha (nit or egg of a louse)
8 liksha       1 yooka (louse)
8 yooka      1 yava (barley corn)
8 yava       1 angula or three-fourths of an inch
12 angula   1 vitasti
2 vitasti     1 kishku hasta (small cubit) or twenty four inches
25 angula   1 praajaapatya(l cubit)
26 angula   1 dhanurmushti
4 dhanur mushti  1 dhanda
8 dhanda   1 rajju

A rajju is the standard length of a rope and works out to 26×4x8 angula or 832 angula or 52 feet. A kishku cubit (24 angula or 18″) also known as hasta is normally used for measuring all objects.

The 3/4″ measurement for angula is as given by Prof. RK.Acharya in his “Encyclopaedia of Architecture”.

However the angula is defined as the middle phalanx of the middle finger in Mayamata and the yava measurement (8 barley grains placed side by side) works out roughly to 3 cms.