diff --git a/cli/diagnostics.rs b/cli/diagnostics.rs
index ba21e5aa95ac09..57c140bda0484f 100644
--- a/cli/diagnostics.rs
+++ b/cli/diagnostics.rs
@@ -77,6 +77,7 @@ const UNSTABLE_DENO_PROPS: &[&str] = &[
   "symlinkSync",
   "systemMemoryInfo",
   "systemCpuInfo",
+  "totalMems",
   "transpileOnly",
   "umask",
   "utime",
diff --git a/cli/dts/lib.deno.unstable.d.ts b/cli/dts/lib.deno.unstable.d.ts
index 6eb39c21c4a20b..fa8a74ed5fd7c6 100644
--- a/cli/dts/lib.deno.unstable.d.ts
+++ b/cli/dts/lib.deno.unstable.d.ts
@@ -190,6 +190,18 @@ declare namespace Deno {
     speed: number | undefined;
   }
 
+  /** **UNSTABLE**: new API, yet to be vetted.
+   *
+   * Returns the total physical memory amount
+   *
+   * ```ts
+   * console.log(Deno.totalMems());
+   * ```
+   *
+   * Requires `allow-env` permission.
+  */
+  export function totalMems(): number;
+
   /** **UNSTABLE**: new API, yet to be vetted.
    *
    * Open and initialize a plugin.
diff --git a/cli/ops/os.rs b/cli/ops/os.rs
index 6fd404a2365323..1d4f83f3d51484 100644
--- a/cli/ops/os.rs
+++ b/cli/ops/os.rs
@@ -24,6 +24,7 @@ pub fn init(rt: &mut deno_core::JsRuntime) {
   super::reg_json_sync(rt, "op_os_release", op_os_release);
   super::reg_json_sync(rt, "op_system_memory_info", op_system_memory_info);
   super::reg_json_sync(rt, "op_system_cpu_info", op_system_cpu_info);
+  super::reg_json_sync(rt, "op_total_mems", op_total_mems);
 }
 
 fn op_exec_path(
@@ -190,3 +191,15 @@ fn op_system_cpu_info(
     "speed": speed
   }))
 }
+
+fn op_total_mems(
+  state: &mut OpState,
+  _args: Value,
+  _zero_copy: &mut [ZeroCopyBuf],
+) -> Result<Value, AnyError> {
+  super::check_unstable(state, "Deno.totalMems");
+  state.borrow::<Permissions>().check_env()?;
+
+  let total_mems = sys_info::mem_info().unwrap().total;
+  Ok(json!({ "totalMems": total_mems }))
+}
diff --git a/cli/rt/30_os.js b/cli/rt/30_os.js
index ebc4e89164743b..d03f32f9754fad 100644
--- a/cli/rt/30_os.js
+++ b/cli/rt/30_os.js
@@ -19,6 +19,10 @@
     return core.jsonOpSync("op_system_memory_info");
   }
 
+  function totalMems() {
+    return core.jsonOpSync("op_total_mems");
+  }
+
   function systemCpuInfo() {
     return core.jsonOpSync("op_system_cpu_info");
   }
@@ -61,6 +65,7 @@
     systemMemoryInfo,
     systemCpuInfo,
     hostname,
+    totalMems,
     loadavg,
   };
 })(this);
diff --git a/cli/rt/90_deno_ns.js b/cli/rt/90_deno_ns.js
index 9188788ec75f16..76f9f8e4e8137f 100644
--- a/cli/rt/90_deno_ns.js
+++ b/cli/rt/90_deno_ns.js
@@ -103,6 +103,7 @@
     openPlugin: __bootstrap.plugins.openPlugin,
     kill: __bootstrap.process.kill,
     setRaw: __bootstrap.tty.setRaw,
+    totalMems: __bootstrap.os.totalMems,
     consoleSize: __bootstrap.tty.consoleSize,
     DiagnosticCategory: __bootstrap.diagnostics.DiagnosticCategory,
     loadavg: __bootstrap.os.loadavg,
diff --git a/cli/tests/unit/os_test.ts b/cli/tests/unit/os_test.ts
index 4e12ddca3c7aad..4927e7faa27330 100644
--- a/cli/tests/unit/os_test.ts
+++ b/cli/tests/unit/os_test.ts
@@ -194,3 +194,8 @@ unitTest({ perms: { env: true } }, function systemCpuInfo(): void {
   assert(cores === undefined || cores > 0);
   assert(speed === undefined || speed > 0);
 });
+
+unitTest({ perms: { env: true } }, function systemCpuInfo(): void {
+  const totalMems = Deno.totalMems();
+  assert(totalMems > 0);
+});
diff --git a/std/node/os.ts b/std/node/os.ts
index 773cca8bdcbe8c..8f478c2467e102 100644
--- a/std/node/os.ts
+++ b/std/node/os.ts
@@ -185,9 +185,9 @@ export function tmpdir(): string | null {
   notImplemented(SEE_GITHUB_ISSUE);
 }
 
-/** Not yet implemented */
+/** Returns total physical memory. **/
 export function totalmem(): number {
-  notImplemented(SEE_GITHUB_ISSUE);
+  return Deno.totalMems();
 }
 
 /** Not yet implemented */