The actual atomic mass of hydrogen depends on which isotope of hydrogen you are referring to. Hydrogen has three isotopes: hydrogen-1 (protium), hydrogen-2 (deuterium), and hydrogen-3 (tritium).
The most abundant and commonly found isotope of hydrogen is hydrogen-1, which consists of a single proton and no neutrons. Its atomic mass is approximately 1.00784 atomic mass units (amu). This value is often rounded to 1 amu for simplicity.
Deuterium, the second isotope of hydrogen, contains one proton and one neutron in its nucleus. It has an atomic mass of approximately 2.014 amu.
Tritium, the least abundant and radioactive isotope of hydrogen, consists of one proton and two neutrons. Its atomic mass is around 3.016 amu.
When discussing the atomic mass of hydrogen, it is generally the atomic mass of hydrogen-1 (protium) that is referred to, unless specified otherwise.