A paper-based sensor was created by Chaiyo et al. to quickly and easily detect the albumin to creatinine ratio (ACR) in urine samples. The sensor used a colorimetric reaction with bromocresol green (BG) in a phosphate buffer (PB) at pH 4 to detect albumin (AL) and creatinine (CR). The presence of AL and/or CR caused BG to change color from greenish-yellow to bluishgreen. Picric acid (PA) in 0.25 M NaOH was used to detect CR, which caused PA to change color from yellow to orange. The working range was 10 to 350 mg dL-1 with a detection limit of 7.1 and 5.4 mg dL-1 for AL + CR and CR detection, respectively. The repeatability was good, with a %RSD value of less than 8.23 (n = 10). The ACR was calculated from the AL and CR colorimetric results. The paper-based sensor was successfully applied to measure AL, CR, and ACR in urine samples, showing good agreement with the standard method. The sensor is a lowcost, simple, sensitive, and promising tool for diagnosing chronic kidney disease (CKD).