diff --git a/packages/fetch-http-handler/src/stream-collector.ts b/packages/fetch-http-handler/src/stream-collector.ts
index a3501ef2d8dc..c820487a8cc1 100644
--- a/packages/fetch-http-handler/src/stream-collector.ts
+++ b/packages/fetch-http-handler/src/stream-collector.ts
@@ -3,11 +3,11 @@ import { fromBase64 } from "@aws-sdk/util-base64-browser";
 
 //reference: https://snack.expo.io/r1JCSWRGU
 export const streamCollector: StreamCollector = (stream: Blob | ReadableStream): Promise<Uint8Array> => {
-  if (stream instanceof Blob) {
+  if (typeof Blob === "function" && stream instanceof Blob) {
     return collectBlob(stream);
   }
 
-  return collectStream(stream);
+  return collectStream(stream as ReadableStream);
 };
 
 async function collectBlob(blob: Blob): Promise<Uint8Array> {
diff --git a/packages/util-body-length-browser/src/index.ts b/packages/util-body-length-browser/src/index.ts
index 3ab61ebf1e63..431f6afeae14 100644
--- a/packages/util-body-length-browser/src/index.ts
+++ b/packages/util-body-length-browser/src/index.ts
@@ -1,6 +1,14 @@
 export function calculateBodyLength(body: any): number | undefined {
   if (typeof body === "string") {
-    return new Blob([body]).size;
+    let len = body.length;
+
+    for (let i = len - 1; i >= 0; i--) {
+      const code = body.charCodeAt(i);
+      if (code > 0x7f && code <= 0x7ff) len++;
+      else if (code > 0x7ff && code <= 0xffff) len += 2;
+    }
+
+    return len;
   } else if (typeof body.byteLength === "number") {
     // handles Uint8Array, ArrayBuffer, Buffer, and ArrayBufferView
     return body.byteLength;