A study from June 15, 1945, by the Joint War Plans Committee, who provided planning information to the Joint Chiefs of Staff, estimated that Olympic would result in between 130,000 and 220,000 U.S. casualties, of which U.S. dead would be in the range from 25,000 to 46,000.
Penelitian tanggal 15 Juni 1945 yang dilakukan oleh Joint War Plans Committee, penyampai informasi perencanaan ke Kepala Staf Gabungan, memperkirakan bahwa Olympic akan mengorbankan antara 130.000 sampai 220.000 tentara A.S., 25.000 sampai 46.000 di antaranya gugur.