U.S. aid in those years was largely based on the Lend-Lease Act. According to Wolfgang Schumann (et al.): Deutschland im Zweiten Weltkrieg. Akademie-Verlag, Berlin 1982, Bd. 3, S. 468.(German Language), aid to China was 1.627 billion dollars (at the time's prices), ranking fourth of all countries. The time period began in April, 1941
The following points give a better understanding of this aid figure:
The aid received before the end of the war was $845 million. Aid did not end immediately after the end.
The total **** of the Lend-Lease bill amounted to about $48.4 billion. China's share was about 3.36%
American GDP at the time was about $200 billion per year. China's share of aid was about 0.8%
To accommodate the US Congress, the Lend-Lease bill stipulated that repayment was required, which is different from the generally envisioned gratuitous aid.
The ratio of dollars at the time converted to today's dollars was roughly 1:10. so the above figure can be multiplied by 10.