diff --git a/client/src/app/features/auth/apis/auth-api.test.ts b/client/src/app/features/auth/apis/auth-api.test.ts
index 7caf468..3bb5b9c 100644
--- a/client/src/app/features/auth/apis/auth-api.test.ts
+++ b/client/src/app/features/auth/apis/auth-api.test.ts
@@ -46,7 +46,10 @@ describe("createAuthApi", () => {
   describe("login", () => {
     it("posts credentials and returns the bearer token from the envelope", async () => {
       fetchSpy.mockResolvedValue(
-        makeOkResponse({ status: "success", data: { token: TOKEN, token_type: "Bearer" } }) as Response,
+        makeOkResponse({
+          status: "success",
+          data: { token: TOKEN, token_type: "Bearer" },
+        }) as Response,
       );
 
       const result = await api.login({ email: "taro@example.com", password: "password123" });
@@ -64,9 +67,9 @@ describe("createAuthApi", () => {
     it("throws on HTTP error", async () => {
       fetchSpy.mockResolvedValue(makeNgResponse(422) as Response);
 
-      await expect(
-        api.login({ email: "taro@example.com", password: "wrong" }),
-      ).rejects.toThrow("HTTP 422");
+      await expect(api.login({ email: "taro@example.com", password: "wrong" })).rejects.toThrow(
+        "HTTP 422",
+      );
     });
   });
 
@@ -117,4 +120,4 @@ describe("createAuthApi", () => {
       await expect(api.getCurrentUser(TOKEN)).rejects.toThrow("HTTP 500");
     });
   });
-});
\ No newline at end of file
+});
diff --git a/client/src/app/features/auth/mapper/__tests__/to-login-request.test.ts b/client/src/app/features/auth/mapper/__tests__/to-login-request.test.ts
new file mode 100644
index 0000000..2145379
--- /dev/null
+++ b/client/src/app/features/auth/mapper/__tests__/to-login-request.test.ts
@@ -0,0 +1,32 @@
+import { describe, it, expect } from "@jest/globals";
+import { toLoginRequest } from "../to-login-request";
+import type { LoginFormValues } from "../../types";
+
+const makeFormValues = (overrides: Partial<LoginFormValues> = {}): LoginFormValues => ({
+  email: "taro@example.com",
+  password: "password123",
+  ...overrides,
+});
+
+describe("toLoginRequest", () => {
+  it("maps form values to the login request", () => {
+    const request = toLoginRequest(makeFormValues());
+
+    expect(request).toEqual({
+      email: "taro@example.com",
+      password: "password123",
+    });
+  });
+
+  it("trims email", () => {
+    const request = toLoginRequest(makeFormValues({ email: "  taro@example.com  " }));
+
+    expect(request.email).toBe("taro@example.com");
+  });
+
+  it("does not trim password", () => {
+    const request = toLoginRequest(makeFormValues({ password: "  spaced out  " }));
+
+    expect(request.password).toBe("  spaced out  ");
+  });
+});
diff --git a/client/src/app/features/auth/mapper/to-login-request.ts b/client/src/app/features/auth/mapper/to-login-request.ts
new file mode 100644
index 0000000..d8cfc45
--- /dev/null
+++ b/client/src/app/features/auth/mapper/to-login-request.ts
@@ -0,0 +1,7 @@
+import type { LoginFormValues } from "../types";
+import type { LoginRequest } from "../apis/auth-api";
+
+export const toLoginRequest = (values: LoginFormValues): LoginRequest => ({
+  email: values.email.trim(),
+  password: values.password,
+});