https://www.britannica.com/topic/Tet-OffensiveThe U.S. military, however, had grown more optimistic following the Tet Offensive. They saw in the successful rebuke of their enemies’ attacks an undeniable weakening of communist forces and strength. By departing from classical guerrilla tactics and assaulting southern cities, the North Vietnamese had unwittingly pitted themselves against their opponents’ greatest strengths. American organizational, material, and logistical superiority was quickly demonstrated in the early hours of the offensive, and the traditionally unreliable South Vietnamese infantry fought with surprising effectiveness. As a result, the communist forces had suffered heavy casualties: an estimated 50,000 Army of North Vietnam and Viet Cong troops killed, missing, or captured. U.S. commander Gen. William C. Westmoreland viewed the post-Tet situation as an opportunity for an American offensive that would further debilitate the enemy and deny any future resurgence. With the encouragement of Joint Chiefs of Staff chairman Gen. Earle Wheeler, Westmoreland renewed an earlier request for more troops. His request was initially denied, however, as Pres. Lyndon B. Johnson did not desire any expansion of the ground war.
Out of their 85,000 man army, they lost 50k. That is a horrific defeat for a guerilla army. They were almost in the dirt at that point. Over the entire war, the NVA lost around 1.1 million troops.
http://www.rjsmith.com/kia_tbl.html