Semakin tingginya permintaan bahan baku kentang untuk french fries khususnya, perlu diimbangi oleh peningkatan suplai kentang dengan kualitas yang memenuhi persyaratan skala industri. Aplikasi dosis pupuk NPK yang tepat serta umur panen yang sesuai merupakan strategi dalam meningkatkan kualitas kentang. Penelitian bertujuan untuk menentukan  dosis pupuk NPK dan umur panen yang dapat menghasilkan ubi kentang dengan kualitas olah terbaik. Percobaan dilakukan dengan menggunakan Rancangan Acak Kelompok pola faktorial dengan dua faktor dan tiga ulangan. Faktor pertama, yaitu dosis pupuk NPK (50, 100, 150% dosis rekomendasi) dan umur panen (90, 105, 120 HST). Hasil penelitian memperlihatkan bahwa perlakuan dosis pupuk NPK dan umur panen tidak memperlihatkan interaksi. Kadar air dan gula reduksi tidak dipengaruhi oleh perlakuan dosis pupuk dan umur panen. Perlakuan dosis pupuk 150 kg N ha-1, 225 kg P ha-1, dan 225 kg K ha-1 menunjukkan kadar pati ubi tertinggi dengan tingkat kerenyahan french fries paling disukai. Perlakuan umur panen 120 hari setelah tanam (HST) memberikan kadar pati dan tingkat kesukaan warna dan kerenyahan french fries paling tinggi.   Abstract The potato demand is increasing, as a raw material for french fries in particular, yet followed by potato improvement to fulfil the industry requirement. The application of NPK fertilizer in appropriate dosage and harvesting time is the essential strategy to increase potato quality. This study aimed to determine the proper dosage of NPK and harvesting time to obtain the best characteristics of potato tuber for processing. The experimental design used a factorial randomized block design consisting of two factors; NPK fertilizer dosages (50, 100, 150% recommended dosage) and harvesting time (90, 105, 120 DAP). NPK fertilizer dosage had no interaction with harvesting time. Tuber water content and reducing sugars were not affected by NPK fertilizer dosage and harvesting time. The treatment of 150 kg N ha-1, 225 kg P ha-1 and 225 kg K ha-1 had the best tuber starch content, and after processing to be french fries, it showed the most favored crispness. Meanwhile, harvesting time at 120 DAP resulted in the highest tuber starch content, french fries colour and crispness score. Giving a certain dose of NPK fertilizer will affect the quality of potato tubers. The right harvesting time affects on the potato tuber quality.