diff --git a/filter.c b/filter.c
index 0eb2dfc..8c0379c 100644
--- a/filter.c
+++ b/filter.c
@@ -8,7 +8,7 @@
 int main(int argc, char *argv[])
 {
     // Define allowable filters
-    char *filters = "bgrsivtmdGoB:";
+    char *filters = "bgrsivtmdGoPB:";
 
     // Allocate filter array
     char *filterArr = (char *)malloc((argc - 2) * sizeof(char));
@@ -49,6 +49,7 @@ int main(int argc, char *argv[])
             printf("  -B <value>  Adjust brightness\n");
             printf("  -G   Glow\n");
             printf("  -o   Oil paint\n");
+            printf("  -P   Pixelate (mosaic effect)\n");
             printf("  -m   Show this menu\n\n");
             free(filterArr);
             return 0;
@@ -60,7 +61,7 @@ int main(int argc, char *argv[])
     if (argc < optind + 2)
     {
         printf("Usage: ./filter [flag] infile outfile\n");
-        printf("Filters: -g (grayscale), -s (sepia), -r (reflect), -b (blur), -i (invert), -v (vignette), -G (glow), -t (threshold), -d (edge detection), -o (oil paint), -B <value> (brightness)\n");
+        printf("Filters: -g (grayscale), -s (sepia), -r (reflect), -b (blur), -i (invert), -v (vignette), -G (glow), -t (threshold), -d (edge detection), -o (oil paint), -P (pixelate), -B <value> (brightness)\n");
         free(filterArr);
         return 3;
     }
@@ -147,6 +148,9 @@ int main(int argc, char *argv[])
             oilpaint(height, width, image);
             break;
 
+        case 'P':  // Pixelate
+            pixelate(height, width, image);
+            break;
         default:
             printf("Unknown filter: %c\n", filterArr[i]);
             free_image(&img);
diff --git a/helpers.c b/helpers.c
index fc2d198..0093e4b 100644
--- a/helpers.c
+++ b/helpers.c
@@ -423,3 +423,42 @@ void oilpaint(int height, int width, RGBTRIPLE image[height][width]){
         free(copy[i]);
     free(copy);
 }
+
+// Pixelate filter
+void pixelate(int height, int width, RGBTRIPLE image[height][width]){
+    int blockSize = 8;
+    if (width > 1000 || height > 1000) {
+        blockSize = 16;
+    } else if (width > 500 || height > 500) {
+        blockSize = 12;
+    }
+    for (int blockY = 0; blockY < height; blockY += blockSize){
+        for (int blockX = 0; blockX < width; blockX += blockSize){
+            int blockEndY = min(blockY + blockSize, height);
+            int blockEndX = min(blockX + blockSize, width);
+            
+            long sumRed = 0, sumGreen = 0, sumBlue = 0;
+            int pixelCount = 0;
+            
+            for (int y = blockY; y < blockEndY; y++){
+                for (int x = blockX; x < blockEndX; x++){
+                    sumRed += image[y][x].rgbtRed;
+                    sumGreen += image[y][x].rgbtGreen;
+                    sumBlue += image[y][x].rgbtBlue;
+                    pixelCount++;
+                }
+            }
+            uint8_t avgRed = (uint8_t)(sumRed / pixelCount);
+            uint8_t avgGreen = (uint8_t)(sumGreen / pixelCount);
+            uint8_t avgBlue = (uint8_t)(sumBlue / pixelCount);
+            
+            for (int y = blockY; y < blockEndY; y++){
+                for (int x = blockX; x < blockEndX; x++){
+                    image[y][x].rgbtRed = avgRed;
+                    image[y][x].rgbtGreen = avgGreen;
+                    image[y][x].rgbtBlue = avgBlue;
+                }
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/helpers.h b/helpers.h
index 13923ad..abd4ae9 100644
--- a/helpers.h
+++ b/helpers.h
@@ -37,4 +37,6 @@ void vignette(int height, int width, RGBTRIPLE image[height][width]);
 void glow(int height, int width, RGBTRIPLE image[height][width]);
 // Oil Paint filter
 void oilpaint(int height, int width, RGBTRIPLE image[height][width]);
+// Pixelate filter
+void pixelate(int height, int width, RGBTRIPLE image[height][width]);
 #endif