diff --git a/src/utils/rate-formatter.test.js b/src/utils/rate-formatter.test.js
new file mode 100644
index 000000000..c49459c0c
--- /dev/null
+++ b/src/utils/rate-formatter.test.js
@@ -0,0 +1,38 @@
+import { createRequire } from "node:module";
+
+import { describe, expect, it } from "vitest";
+
+const require = createRequire(import.meta.url);
+const i18nextConfig = require("../../next-i18next.config.js");
+
+function getRateFormatter() {
+  let rateFormatter;
+
+  i18nextConfig.use[0].init({
+    services: {
+      formatter: {
+        add(name, formatter) {
+          if (name === "rate") rateFormatter = formatter;
+        },
+      },
+    },
+  });
+
+  return rateFormatter;
+}
+
+describe("rate formatter", () => {
+  const formatRate = getRateFormatter();
+
+  it.each([
+    ["zero bytes", 0, { binary: true, bits: false, decimals: 1 }, "0 B/s"],
+    ["decimal bytes", 15_000, { binary: false, bits: false, decimals: 1 }, "15.0 kB/s"],
+    ["binary bytes as mebibytes", 512, { binary: true, bits: false, decimals: 1 }, "0.0 MiB/s"],
+    ["binary kibibytes as mebibytes", 15 * 1024, { binary: true, bits: false, decimals: 1 }, "0.0 MiB/s"],
+    ["binary mebibytes", 15 * 1024 ** 2, { binary: true, bits: false, decimals: 1 }, "15.0 MiB/s"],
+    ["binary gibibytes as mebibytes", 2 * 1024 ** 3, { binary: true, bits: false, decimals: 1 }, "2,048.0 MiB/s"],
+    ["binary bits as mebibits", 15 * 1024, { binary: true, bits: true, decimals: 1 }, "0.0 Mibit/s"],
+  ])("formats %s", (_description, value, options, expected) => {
+    expect(formatRate(value, "en", options)).toBe(expected);
+  });
+});