<![CDATA[Poor inventory management is a primary challenge for telecommunications service providers. This study implements the weighted moving average (WMA) algorithm with window size variations to forecast demand for kabel drop core and Optical Network Terminal (ONT) at Fibertrust Madiun, integrating it with Safety Stock (SS) and Reorder Point (ROP) calculations. The data covers 63 kabel drop core transactions and 112 ONT transactions during January–December 2025, with coefficients of variation of 0.384 and 0.567 respectively. Three window sizes (3, 4, and 5 periods) were tested using MAD, MSE, and MAPE. Window 5 achieved the best accuracy with MAPE of 27.11% for kabel drop core and 47.57% for ONT, both in the sufficient category. A 95% service level provides the optimal balance between holding cost and stockout risk. ROP implementation has the potential to reduce stockout incidents by 71–79%, from 28 to 6–8 incidents per year.Keywords: Weighted moving average; Reorder point; Safety stock; Inventory management; StockoutAbstrakPengelolaan persediaan yang tidak tertata dengan baik menjadi tantangan utama perusahaan penyedia layanan telekomunikasi. Penelitian ini mengimplementasikan algoritma weighted moving average (WMA) dengan variasi ukuran window untuk meramalkan permintaan kabel drop core dan Optical Network Terminal (ONT) di Fibertrust Madiun, serta mengintegrasikannya dengan perhitungan Safety Stock (SS) dan Reorder Point (ROP). Data mencakup 63 transaksi kabel drop core dan 112 transaksi ONT selama Januari-Desember 2025, dengan koefisien variasi masing-masing 0,384 dan 0,567. Tiga variasi ukuran window (3, 4, dan 5 periode) diuji menggunakan metrik MAD, MSE, dan MAPE. Window 5 periode mencatat akurasi terbaik dengan MAPE 27,11% untuk kabel drop core dan 47,57% untuk ONT, keduanya berkategori cukup. Service level 95% memberikan keseimbangan terbaik antara biaya penyimpanan dan risiko kehabisan stok (stockout). Penerapan ROP berpotensi menekan insiden stockout hingga 71-79%, dari 28 insiden menjadi 6-8 insiden per tahun. ]]>
