Planck units

Planck units are a set of physical units based upon Planck constant and other fundamental constants, one type of natural units. (Such systems of natural units can be designed so as to simplify equations.) Some Plank units, such as Planck length and Planck time reflect minimal scales regarding the regime of current physical laws. Others are within or above the range of "normal" units.

tP ≡ √(ℏG/c5)
lP ≡ √(ℏG/c3)
mP ≡ √(ℏc/G)
EP ≡ mPc2
TP ≡ EP/KB

• t_P - Planck time (which is about 5.39 × 10^-44 s).
• l_P - Planck length (about 1.62 × 10^-35 cm).
• m_P - Planck mass (not extremely small: about 2.18 × 10^-5 g, roughly that of a millimeter of human hair, and according to some laws, the minimum possible mass of a black hole, i.e., a Planck hole).
• E_P - Planck energy (moderate: about 1.9561 × 10⁹ J, the energy from burning about 16 gallons of gasoline).
• T_P - Planck temperature (extremely large: about 1.41678516 × 10³² K, and by some theories, the maximum possible temperature, or maximum for which current physical rules apply, sometimes termed absolute hot).
• ℏ - reduced Planck constant.
• G - gravitational constant.
• c - speed of light in a vacuum.
• K_B - Boltzmann constant.