diff --git a/apps/api/src/routes/v1_keys_createKey.happy.test.ts b/apps/api/src/routes/v1_keys_createKey.happy.test.ts
index d8a8be632d..aac372967f 100644
--- a/apps/api/src/routes/v1_keys_createKey.happy.test.ts
+++ b/apps/api/src/routes/v1_keys_createKey.happy.test.ts
@@ -6,6 +6,7 @@ import { eq, schema } from "@unkey/db";
 import { newId } from "@unkey/id";
 import { IntegrationHarness } from "src/pkg/testutil/integration-harness";
 
+import { KeyV1 } from "@unkey/keys";
 import type { V1KeysCreateKeyRequest, V1KeysCreateKeyResponse } from "./v1_keys_createKey";
 
 test("creates key", async (t) => {
@@ -34,6 +35,50 @@ test("creates key", async (t) => {
   expect(found!.hash).toEqual(await sha256(res.body.key));
 });
 
+test("creates key with default prefix and bytes from keyAuth", async (t) => {
+  const expectedPrefix = "_prefix";
+  const expectedBytes = 66;
+
+  const h = await IntegrationHarness.init(t);
+  const root = await h.createRootKey([`api.${h.resources.userApi.id}.create_key`]);
+
+  await h.db.primary
+    .update(schema.keyAuth)
+    .set({
+      defaultPrefix: expectedPrefix,
+      defaultBytes: expectedBytes,
+    })
+    .where(eq(schema.keyAuth.id, h.resources.userKeyAuth.id));
+
+  // Make the request without specifying prefix or byteLength
+  const res = await h.post<V1KeysCreateKeyRequest, V1KeysCreateKeyResponse>({
+    url: "/v1/keys.createKey",
+    headers: {
+      "Content-Type": "application/json",
+      Authorization: `Bearer ${root.key}`,
+    },
+    body: {
+      apiId: h.resources.userApi.id,
+      enabled: true,
+    },
+  });
+
+  expect(res.status, `expected 200, received: ${JSON.stringify(res, null, 2)}`).toBe(200);
+
+  const found = await h.db.primary.query.keys.findFirst({
+    where: (table, { eq }) => eq(table.id, res.body.keyId),
+  });
+
+  const referenceKey = new KeyV1({
+    byteLength: expectedBytes,
+    prefix: expectedPrefix,
+  }).toString();
+
+  expect(found).toBeDefined();
+  expect(found!.start).toEqual(referenceKey.slice(0, 5));
+  expect(found!.hash).toEqual(await sha256(res.body.key));
+});
+
 describe("with enabled flag", () => {
   describe("not set", () => {
     test("should still create an enabled key", async (t) => {
diff --git a/apps/api/src/routes/v1_keys_createKey.ts b/apps/api/src/routes/v1_keys_createKey.ts
index 709bc08ffd..db1209ed31 100644
--- a/apps/api/src/routes/v1_keys_createKey.ts
+++ b/apps/api/src/routes/v1_keys_createKey.ts
@@ -279,6 +279,7 @@ export const registerV1KeysCreateKey = (app: App) =>
         })) ?? null
       );
     });
+
     if (err) {
       throw new UnkeyApiError({
         code: "INTERNAL_SERVER_ERROR",
@@ -350,10 +351,12 @@ export const registerV1KeysCreateKey = (app: App) =>
           apiId: api.id,
         });
       }
+
       const secret = new KeyV1({
-        byteLength: req.byteLength ?? 16,
-        prefix: req.prefix,
+        byteLength: req.byteLength ?? api.keyAuth?.defaultBytes ?? 16,
+        prefix: req.prefix ?? (api.keyAuth?.defaultPrefix as string | undefined),
       }).toString();
+
       const start = secret.slice(0, (req.prefix?.length ?? 0) + 5);
       const kId = newId("key");
       const hash = await sha256(secret.toString());
diff --git a/apps/dashboard/app/(app)/apis/[apiId]/keys/[keyAuthId]/new/client.tsx b/apps/dashboard/app/(app)/apis/[apiId]/keys/[keyAuthId]/new/client.tsx
index 1cf452c243..7393667793 100644
--- a/apps/dashboard/app/(app)/apis/[apiId]/keys/[keyAuthId]/new/client.tsx
+++ b/apps/dashboard/app/(app)/apis/[apiId]/keys/[keyAuthId]/new/client.tsx
@@ -85,13 +85,18 @@ export const CreateKey = ({ apiId, keyAuthId, defaultBytes, defaultPrefix }: Pro
   });
 
   async function onSubmit(values: z.infer<typeof formSchema>) {
-    if (values.limit?.refill?.interval !== "none" && !values.limit?.refill?.amount) {
+    if (
+      values.limitEnabled &&
+      values.limit?.refill?.interval !== "none" &&
+      !values.limit?.refill?.amount
+    ) {
       form.setError("limit.refill.amount", {
         type: "manual",
         message: "Please enter a value if interval is selected",
       });
       return;
     }
+
     if (!values.expireEnabled) {
       delete values.expires;
     }