diff --git a/examples/src/simple.ts b/examples/src/simple.ts
index 71806a5..84733cb 100644
--- a/examples/src/simple.ts
+++ b/examples/src/simple.ts
@@ -37,19 +37,19 @@ await bench.run();
 console.table(
   bench.tasks.map(({ name, result }) => (result ? ({
     'Task Name': name,
-    'ops/sec': result.hz,
-    'Average Time (ps)': result.mean * 1000,
-    'Variance (ps)': result.variance * 1000,
+    'ops/sec': parseInt(result.hz, 10).toLocaleString(),
+    'Average Time (ns)': result.mean * 1000 * 1000,
+    Margin: `\xb1${result.rme.toFixed(2)}%`,
     Samples: result.samples.length,
   }) : null)),
 );
 
 // Output:
-// ┌─────────┬──────────────────┬────────────────────┬─────────────────────┬───────────────────────┬─────────┐
-// │ (index) │    Task Name     │      ops/sec       │  Average Time (ps)  │     Variance (ps)     │ Samples │
-// ├─────────┼──────────────────┼────────────────────┼─────────────────────┼───────────────────────┼─────────┤
-// │    0    │    'switch 1'    │ 14463.371878123484 │ 0.06914017066190119 │ 0.006014460930767669  │ 414836  │
-// │    1    │    'switch 2'    │ 14880.867755337544 │ 0.06720038215790977 │ 0.0004529273320957288 │ 458644  │
-// │    2    │ 'async switch 1' │  7970.65255150332  │ 0.1254602422497256  │ 0.010617119343817942  │ 367049  │
-// │    3    │ 'async switch 2' │ 8702.849913513868  │ 0.11490488862127687 │ 0.002613875857497825  │ 389356  │
-// └─────────┴──────────────────┴────────────────────┴─────────────────────┴───────────────────────┴─────────┘
+// ┌─────────┬──────────────────┬──────────────┬────────────────────┬──────────┬─────────┐
+// │ (index) │    Task Name     │   ops/sec    │ Average Time (ns)  │  Margin  │ Samples │
+// ├─────────┼──────────────────┼──────────────┼────────────────────┼──────────┼─────────┤
+// │    0    │    'switch 1'    │ '15,370,548' │ 65.05948714494949  │ '±1.89%' │ 1537055 │
+// │    1    │    'switch 2'    │ '14,826,005' │ 67.44905232421046  │ '±2.69%' │ 1482601 │
+// │    2    │ 'async switch 1' │ '8,196,259'  │ 122.00687003709369 │ '±5.01%' │ 819626  │
+// │    3    │ 'async switch 2' │ '7,830,281'  │ 127.7093250277111  │ '±5.79%' │ 788521  │
+// └─────────┴──────────────────┴──────────────┴────────────────────┴──────────┴─────────┘
diff --git a/package.json b/package.json
index 084874a..47c3e49 100644
--- a/package.json
+++ b/package.json
@@ -3,9 +3,6 @@
   "version": "2.3.0",
   "type": "module",
   "packageManager": "pnpm@7.5.1",
-  "engines": {
-    "node": ">= 10.0.0"
-  },
   "scripts": {
     "dev": "tsup --watch",
     "build": "tsup",
diff --git a/src/bench.ts b/src/bench.ts
index ffbe4d5..366a008 100644
--- a/src/bench.ts
+++ b/src/bench.ts
@@ -8,7 +8,7 @@ import type {
 } from 'types/index';
 import { createBenchEvent } from './event';
 import Task from './task';
-import { now } from './utils';
+import { isAsyncFunction, isAsyncFunctionDirty, now } from './utils';
 
 /**
  * The Benchmark instance for keeping track of the benchmark tasks and controlling
@@ -32,6 +32,8 @@ export default class Bench extends EventTarget {
 
   now = now;
 
+  isAsyncFunction: (fn: Fn) => boolean;
+
   setup: Hook;
 
   teardown: Hook;
@@ -42,6 +44,7 @@ export default class Bench extends EventTarget {
     this.warmupTime = options.warmupTime ?? this.warmupTime;
     this.warmupIterations = options.warmupIterations ?? this.warmupIterations;
     this.time = options.time ?? this.time;
+    this.isAsyncFunction = options.dirtyAsyncCheck ? isAsyncFunctionDirty : isAsyncFunction;
     this.iterations = options.iterations ?? this.iterations;
     this.signal = options.signal;
     // eslint-disable-next-line @typescript-eslint/no-empty-function
diff --git a/src/task.ts b/src/task.ts
index 7dbe5f4..0236698 100644
--- a/src/task.ts
+++ b/src/task.ts
@@ -1,11 +1,10 @@
 import type {
   Fn, TaskEvents, TaskResult, TaskEventsMap,
 } from 'types/index';
-import { types } from 'util';
 import Bench from './bench';
 import tTable from './constants';
 import { createBenchEvent } from './event';
-import { getMean, getSum, getVariance } from './utils';
+import { getMean, getVariance } from './utils';
 
 /**
  * A class that represents each benchmark task in Tinybench. It keeps track of the
@@ -46,9 +45,9 @@ export default class Task extends EventTarget {
    */
   async run() {
     this.dispatchEvent(createBenchEvent('start', this));
-    const startTime = this.bench.now(); // ms
     let totalTime = 0; // ms
     const samples: number[] = [];
+    const isAsync = this.bench.isAsyncFunction(this.fn);
 
     await this.bench.setup(this, 'run');
     while (
@@ -56,7 +55,6 @@ export default class Task extends EventTarget {
       && !this.bench.signal?.aborted
     ) {
       let taskStart = 0;
-      const isAsync = types.isAsyncFunction(this.fn);
 
       try {
         taskStart = this.bench.now();
@@ -68,11 +66,10 @@ export default class Task extends EventTarget {
         const taskTime = this.bench.now() - taskStart;
         this.runs += 1;
         samples.push(taskTime);
+        totalTime += taskTime;
       } catch (e) {
         this.setResult({ error: e });
       }
-
-      totalTime = this.bench.now() - startTime;
     }
     await this.bench.teardown(this, 'run');
 
@@ -81,8 +78,8 @@ export default class Task extends EventTarget {
     {
       const min = samples[0]!;
       const max = samples[samples.length - 1]!;
-      const period = getSum(samples) / this.runs;
-      const hz = 1 / period;
+      const period = totalTime / this.runs;
+      const hz = 1000 / period;
 
       // benchmark.js: https://github.com/bestiejs/benchmark.js/blob/42f3b732bac3640eddb3ae5f50e445f3141016fd/benchmark.js#L1912-L1927
       const mean = getMean(samples);
diff --git a/src/utils.ts b/src/utils.ts
index 62c6e5b..7a7bf51 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,3 +1,5 @@
+import { Fn } from 'types';
+
 export const nanoToMs = (nano: number) => nano / 1e6;
 
 export const now = () => {
@@ -20,7 +22,23 @@ export const getVariance = (samples: number[], mean: number) => {
   return result / (samples.length - 1) || 0;
 };
 
+// eslint-disable-next-line @typescript-eslint/no-empty-function
+const AsyncFunctionConstructor = (async () => {}).constructor;
+
 /**
- * Computes the sum of a sample
+ * an async function check method only consider runtime support async syntax
  */
-export const getSum = (samples: number[]) => samples.reduce((sum, n) => sum + n, 0);
+export const isAsyncFunction = (fn: Fn) => fn.constructor === AsyncFunctionConstructor;
+
+/**
+ * an async function check method consider runtime not support async syntax
+ */
+export const isAsyncFunctionDirty = (fn: Fn) => {
+  try {
+    const ret = fn();
+    return !!ret && typeof ret === 'object' && typeof ret.then === 'function';
+  } catch {
+    // if fn throw error directly, consider it's a sync function
+    return false;
+  }
+};
diff --git a/test/index.test.ts b/test/index.test.ts
index 346406c..dc99cb3 100644
--- a/test/index.test.ts
+++ b/test/index.test.ts
@@ -23,7 +23,8 @@ test('basic', async () => {
   expect(tasks[1]!.name).toEqual('bar');
   expect(tasks[1]!.result!.totalTime).toBeGreaterThan(100);
 
-  expect(tasks[0]!.result!.hz * tasks[0]!.result!.period).toBeCloseTo(1);
+  // hz is ops/sec, period is ms unit value
+  expect(tasks[0]!.result!.hz * tasks[0]!.result!.period).toBeCloseTo(1000);
 });
 
 test('runs should be equal-more than time and iterations', async () => {
@@ -48,7 +49,9 @@ test('events order', async () => {
     warmupTime: 0,
   });
   bench
+    // eslint-disable-next-line @typescript-eslint/no-empty-function
     .add('foo', async () => {})
+    // eslint-disable-next-line @typescript-eslint/no-empty-function
     .add('bar', async () => {})
     .add('error', async () => {
       throw new Error('fake');
diff --git a/types/index.d.ts b/types/index.d.ts
index 0e76155..a0b8f78 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -179,6 +179,16 @@ export type Options = {
    */
   now?: () => number;
 
+  /**
+   * decide use which way to check task's fn is a async function.
+   *
+   * when it's false, only compare function's constructor
+   * when is's true, run task's fn and check whether return a PromiseLike object
+   *
+   * @default false
+   */
+  dirtyAsyncCheck?: boolean;
+
   /**
    * An AbortSignal for aborting the benchmark
    */