diff --git a/cpp/src/arrow/tensor_benchmark.cc b/cpp/src/arrow/tensor_benchmark.cc
index 67bd1a8c89901..8cace41d6004f 100644
--- a/cpp/src/arrow/tensor_benchmark.cc
+++ b/cpp/src/arrow/tensor_benchmark.cc
@@ -30,7 +30,8 @@ static void BatchToTensorSimple(benchmark::State& state) {
   using CType = typename ValueType::c_type;
   std::shared_ptr<DataType> ty = TypeTraits<ValueType>::type_singleton();
 
-  const int64_t kNumRows = state.range(0) / sizeof(CType);
+  const int64_t num_cols = state.range(1);
+  const int64_t num_rows = state.range(0) / num_cols / sizeof(CType);
   arrow::random::RandomArrayGenerator gen_{42};
 
   std::vector<std::shared_ptr<Field>> fields = {};