diff --git a/lib/os/heap-validate.c b/lib/os/heap-validate.c
index ac9bef13856..433c586b206 100644
--- a/lib/os/heap-validate.c
+++ b/lib/os/heap-validate.c
@@ -343,7 +343,7 @@ void heap_print_info(struct z_heap *h, bool dump_chunks)
 		if (count) {
 			printk("%9d %12d %12d %12zd %12zd\n",
 			       i, (1 << i) - 1 + min_chunk_size(h), count,
-			       largest, largest * CHUNK_UNIT - chunk_header_bytes(h));
+			       largest, chunksz_to_bytes(h, largest));
 		}
 	}
 
@@ -355,11 +355,9 @@ void heap_print_info(struct z_heap *h, bool dump_chunks)
 		if (c == 0 || c == h->end_chunk) {
 			/* those are always allocated for internal purposes */
 		} else if (chunk_used(h, c)) {
-			allocated_bytes += chunk_size(h, c) * CHUNK_UNIT
-						- chunk_header_bytes(h);
+			allocated_bytes += chunksz_to_bytes(h, chunk_size(h, c));
 		} else if (!solo_free_header(h, c)) {
-			free_bytes += chunk_size(h, c) * CHUNK_UNIT
-						- chunk_header_bytes(h);
+			free_bytes += chunksz_to_bytes(h, chunk_size(h, c));
 		}
 		if (dump_chunks) {
 			printk("chunk %4zd: [%c] size=%-4zd left=%-4zd right=%zd\n",
diff --git a/lib/os/heap.c b/lib/os/heap.c
index 22ecce05914..6cf9ed6dd7b 100644
--- a/lib/os/heap.c
+++ b/lib/os/heap.c
@@ -367,8 +367,7 @@ void *sys_heap_aligned_realloc(struct sys_heap *heap, void *ptr,
 	void *ptr2 = sys_heap_aligned_alloc(heap, align, bytes);
 
 	if (ptr2 != NULL) {
-		size_t prev_size = chunk_size(h, c) * CHUNK_UNIT
-				   - chunk_header_bytes(h) - align_gap;
+		size_t prev_size = chunksz_to_bytes(h, chunk_size(h, c)) - align_gap;
 
 		memcpy(ptr2, ptr, MIN(prev_size, bytes));
 		sys_heap_free(heap, ptr);
diff --git a/lib/os/heap.h b/lib/os/heap.h
index 416d9c24c55..2b0b2b5521b 100644
--- a/lib/os/heap.h
+++ b/lib/os/heap.h
@@ -228,6 +228,11 @@ static inline int min_chunk_size(struct z_heap *h)
 	return bytes_to_chunksz(h, 1);
 }
 
+static inline size_t chunksz_to_bytes(struct z_heap *h, size_t chunksz)
+{
+	return chunksz * CHUNK_UNIT - chunk_header_bytes(h);
+}
+
 static inline int bucket_idx(struct z_heap *h, size_t sz)
 {
 	size_t usable_sz = sz - min_chunk_size(h) + 1;