Guagua is a landlocked municipality in the coastal province of Pampanga.
The municipality has a land area of 48.67 square kilometers or 18.79 square miles which constitutes 2.43% of Pampanga's total area. Its population as determined by the 2020 Census was 128,893. This represented 5.29% of the total population of Pampanga province, or 1.04% of the overall population of the Central Luzon region. Based on these figures, the population density is computed at 2,648 inhabitants per square kilometer or 6,860 inhabitants per square mile.