diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8ef223d..29742b9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/). Thi
 ### Added
 
 - `openmail inbox create` and `openmail init` accept `--domain <domain>` to create an inbox on a verified custom domain you own. When omitted, the inbox uses your account default domain.
+- `openmail usage` — per-inbox usage (inbound/outbound counts, attachment bytes, stored bytes) plus account totals, with `--from`, `--to`, and `--group-by inbox|account` flags.
 
 ---
 
diff --git a/README.md b/README.md
index f91ede9..b02c574 100644
--- a/README.md
+++ b/README.md
@@ -44,6 +44,9 @@ openmail inbox create [--mailbox-name <name>] [--display-name <sender name>] [--
 openmail inbox get --id inb_xxx
 openmail inbox delete --id inb_xxx
 
+# Per-inbox usage (emails + storage) for metering
+openmail usage [--from <ISO8601>] [--to <ISO8601>] [--group-by inbox|account]
+
 # Send email (uses default inbox from setup/init, or pass --inbox-id)
 openmail send --to hello@example.com --subject "Hi" --body "Hello"
 
diff --git a/src/commands/__tests__/usage.test.ts b/src/commands/__tests__/usage.test.ts
new file mode 100644
index 0000000..ebd5aaf
--- /dev/null
+++ b/src/commands/__tests__/usage.test.ts
@@ -0,0 +1,42 @@
+import { describe, expect, it, vi } from "vitest";
+import { parseArgs } from "../../lib/args";
+import { runUsageCommand } from "../usage";
+import type { OpenMailHttpClient } from "../../lib/http";
+
+function makeClient() {
+  return {
+    get: vi.fn().mockResolvedValue({ groupBy: "inbox", inboxes: [], totals: {} }),
+  } as unknown as OpenMailHttpClient & { get: ReturnType<typeof vi.fn> };
+}
+
+describe("runUsageCommand", () => {
+  it("passes from/to/group-by as query params", async () => {
+    const client = makeClient();
+    const parsed = parseArgs([
+      "usage",
+      "--from",
+      "2026-05-01T00:00:00Z",
+      "--to",
+      "2026-06-01T00:00:00Z",
+      "--group-by",
+      "account",
+    ]);
+
+    await runUsageCommand(client, parsed);
+
+    expect(client.get).toHaveBeenCalledWith("/v1/usage", {
+      from: "2026-05-01T00:00:00Z",
+      to: "2026-06-01T00:00:00Z",
+      group_by: "account",
+    });
+  });
+
+  it("sends no query params when no flags are given", async () => {
+    const client = makeClient();
+    const parsed = parseArgs(["usage"]);
+
+    await runUsageCommand(client, parsed);
+
+    expect(client.get).toHaveBeenCalledWith("/v1/usage", {});
+  });
+});
diff --git a/src/commands/usage.ts b/src/commands/usage.ts
new file mode 100644
index 0000000..c399642
--- /dev/null
+++ b/src/commands/usage.ts
@@ -0,0 +1,15 @@
+import type { ParsedArgs } from "../lib/args";
+import { getStringFlag } from "../lib/args";
+import type { OpenMailHttpClient } from "../lib/http";
+
+export async function runUsageCommand(client: OpenMailHttpClient, parsed: ParsedArgs) {
+  const from = getStringFlag(parsed.flags, "from");
+  const to = getStringFlag(parsed.flags, "to");
+  const groupBy = getStringFlag(parsed.flags, "group-by");
+
+  return client.get("/v1/usage", {
+    ...(from ? { from } : {}),
+    ...(to ? { to } : {}),
+    ...(groupBy ? { group_by: groupBy } : {}),
+  });
+}
diff --git a/src/index.ts b/src/index.ts
index 68f379d..0920899 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -3,6 +3,7 @@
 import { getBooleanFlag, parseArgs } from "./lib/args";
 import { version } from "../package.json";
 import { runInboxCommand } from "./commands/inbox";
+import { runUsageCommand } from "./commands/usage";
 import { runMessagesCommand } from "./commands/messages";
 import { runThreadsCommand } from "./commands/threads";
 import { runSendCommand } from "./commands/send";
@@ -162,6 +163,8 @@ async function main() {
     });
   } else if (command === "inbox") {
     output = await runInboxCommand(client, parsed);
+  } else if (command === "usage") {
+    output = await runUsageCommand(client, parsed);
   } else if (command === "send") {
     const inboxId = await resolveInboxIdWithFallback({
       client,
@@ -261,6 +264,7 @@ function printHelp(topic?: string) {
         "  status     Show current OpenMail/OpenClaw runtime status",
         "  init       Create a new inbox and set as default",
         "  inbox      Manage inboxes",
+        "  usage      Show per-inbox usage (emails + storage)",
         "  send       Send an email",
         "  messages   List messages for an inbox",
         "  threads    List/get threads",
@@ -359,6 +363,22 @@ function printHelp(topic?: string) {
     return;
   }
 
+  if (usage === "usage") {
+    process.stdout.write(
+      [
+        "openmail usage",
+        "",
+        "Usage:",
+        "  usage [--from <ISO8601>] [--to <ISO8601>] [--group-by inbox|account]",
+        "",
+        "Shows per-inbox usage (inbound/outbound counts, attachment bytes, stored bytes) plus account totals. Defaults to the last 30 days; max window is 92 days. Use --json for machine-readable output.",
+        "",
+        ...globalFlags,
+      ].join("\n"),
+    );
+    return;
+  }
+
   if (usage === "send") {
     process.stdout.write(
       [