diff --git a/src/exact-inconsistency.ts b/src/exact-inconsistency.ts
new file mode 100644
index 0000000..165fd60
--- /dev/null
+++ b/src/exact-inconsistency.ts
@@ -0,0 +1,67 @@
+export type ExactEvent = {
+  progress: number;
+  done: boolean;
+  size: number;
+  consistent?: boolean;
+  detail: string;
+  error?: string;
+};
+export type ExactJobType = "one-one" | "group";
+export type ExactJob = {
+  key: ["jobs", string];
+  value: {
+    events: ExactEvent[] | ExactEvent[][];
+    createdAt: string;
+    status: string;
+    error?: string;
+    params?: {
+      job_type?: ExactJobType;
+    };
+  };
+};
+
+function getInconsistency(
+  event: ExactEvent
+): { offset: number; width: number; size: number }[] {
+  const inConsistencies: { offset: number; width: number; size: number }[] = [];
+  try {
+    const { size, detail } = event || {};
+    const { buffer_size, in_consistent_offsets } = JSON.parse(detail);
+    const width = (100 * buffer_size) / size;
+
+    for (const o of in_consistent_offsets) {
+      const offset = (100 * o) / size;
+      inConsistencies.push({
+        offset,
+        width,
+        size,
+      });
+    }
+    return inConsistencies;
+  } catch {
+    return inConsistencies;
+  }
+}
+
+/**
+ * Calculate the inconsistency percentage (0-100) with the result of exact's
+ * [get-job api](http://gitlab.smartx.com/frontend/exact/-/blob/master/routes/api/get-job.ts).
+ *
+ * @returns Note that the range is 0-100, not 0-1
+ */
+export function getInconsistencyPercent(events: ExactJob['value']['events']): number {
+  let total = 0;
+  let sum = 0;
+  for (const event of events) {
+    if (Array.isArray(event)) {
+      continue;
+    }
+    const inconsistency = getInconsistency(event);
+    total += event.size;
+    for (const ic of inconsistency) {
+      sum += ic.size * ic.width;
+    }
+  }
+
+  return sum / total || 0;
+}
diff --git a/src/index.ts b/src/index.ts
index ed0a4a1..dd190a7 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,3 +1,9 @@
-export { getOne } from "./get-one";
-export { waitUntil, Wait } from "./wait";
-export { formatResponseError } from "./error";
+export { getOne } from "./get-one.ts";
+
+export { waitUntil } from "./wait.ts";
+export type { Wait } from './wait.ts';
+
+export { formatResponseError } from "./error.ts";
+
+export { getInconsistencyPercent } from './exact-inconsistency.ts'
+export type { ExactEvent, ExactJob, ExactJobType } from './exact-inconsistency.ts'