Tablet appearance: The tablet appearance is considered as one of the most important factor in evaluation based on the consumer acceptance. It also ensures whether the lot of batch of tablets produced has maintained uniformity in its elegance, which includes color, taste, presence of flavor, identifying marks, surface texture, etc.

Organoleptic parameters: The organoleptic parameters, which are considered in tablets, mainly include its color, taste and odor.

1. Color of the tablet: The color distribution within the tablets should be uniform, and it should not vary from one lot to another. Non-uniform distribution of color within a tablet is known as mottling. Mottling should be avoided as it not only provides a poor appearance to the tablet but also does not give a satisfactory look to the consumer. Hence, color distribution in a tablet is quantitatively evaluated by the following instruments:
   1. Tristimulus calorimetric measurements
   2. Reflectance spectrophotometry
   3. Micro reflectance photometer
2. Odor of the tablet: This helps to know whether the tablet has deteriorated thereby stability of the tablet is affected. For example, Aspirin tablet—instability indicated by a characteristic acetic acid odor.

Identification markings on tablet: These include name or symbol of the company and code of the product. These symbols are engraved and printed on the tablet surface, which helps in quick referral of the tablet when searched for identification.

Size and shape of the tablet: Tablets are designed to allow rapid production, to enable good consumer acceptance and also for identification.

Thickness of the tablet: The thickness of the tablet is influenced by the amount of fill material in the die cavity, die diameter and the compaction force applied. Thickness specification is characteristic to each tablet product, but in general the tablet thickness is required to be within ±5% of the prescribed values.

Factors affecting tablet thickness

1. The true and bulk density and also the crystalline nature of the raw material influence the tablet thickness.
2. The particle size and size distribution of the granules affect the tablet thickness.
3. The length of both upper and lower punches should be uniform, if not it affects the tablet thickness.

Thickness of the tablet is evaluated by micrometer digital readout sliding caliper scale method.

Hardness of the tablet: It is also termed as its crushing strength. It may be defined as the compressional force required to break or fracture the tablet when such force is applied diametrically. It is influenced by three variables—bonding strength, internal strain and brittleness. It is determined using the instrument Monsanto Hardness Tester or Pfizer Hardness Tester, and expressed with the units kg/cm².