diff --git a/src/commands/PerpsCommand.ts b/src/commands/PerpsCommand.ts
index 313872c..2e86304 100644
--- a/src/commands/PerpsCommand.ts
+++ b/src/commands/PerpsCommand.ts
@@ -5,6 +5,7 @@ import type { Command } from "commander";
 import { PerpsClient } from "../clients/PerpsClient.ts";
 import { Asset, resolveAsset } from "../lib/Asset.ts";
 import { Config } from "../lib/Config.ts";
+import { DateConverter } from "../lib/DateConverter.ts";
 import { NumberConverter } from "../lib/NumberConverter.ts";
 import { Output } from "../lib/Output.ts";
 import { Signer } from "../lib/Signer.ts";
@@ -904,14 +905,7 @@ export class PerpsCommand {
   }
 
   private static parseTimestamp(value: string): string {
-    if (/^\d+$/.test(value)) {
-      return value;
-    }
-    const ms = new Date(value).getTime();
-    if (isNaN(ms)) {
-      throw new Error(`Invalid date: ${value}`);
-    }
-    return String(Math.floor(ms / 1000));
+    return DateConverter.parseTimestamp(value);
   }
 
   private static async history(opts: {
diff --git a/src/commands/SpotCommand.ts b/src/commands/SpotCommand.ts
index ab28856..6255940 100644
--- a/src/commands/SpotCommand.ts
+++ b/src/commands/SpotCommand.ts
@@ -15,6 +15,7 @@ import {
 } from "../clients/UltraClient.ts";
 import { Asset, resolveWalletAsset } from "../lib/Asset.ts";
 import { Config } from "../lib/Config.ts";
+import { DateConverter } from "../lib/DateConverter.ts";
 import { NumberConverter } from "../lib/NumberConverter.ts";
 import { Output } from "../lib/Output.ts";
 import { Signer } from "../lib/Signer.ts";
@@ -928,13 +929,6 @@ export class SpotCommand {
   }
 
   private static parseTimestamp(value: string): string {
-    if (/^\d+$/.test(value)) {
-      return new Date(Number(value) * 1000).toISOString();
-    }
-    const ms = new Date(value).getTime();
-    if (isNaN(ms)) {
-      throw new Error(`Invalid date: ${value}`);
-    }
-    return new Date(ms).toISOString();
+    return DateConverter.parseTimestamp(value);
   }
 }
diff --git a/src/lib/DateConverter.ts b/src/lib/DateConverter.ts
new file mode 100644
index 0000000..a1baeaa
--- /dev/null
+++ b/src/lib/DateConverter.ts
@@ -0,0 +1,16 @@
+export class DateConverter {
+  /**
+   * Parse a timestamp string (ISO date or UNIX timestamp) and return Unix seconds.
+   * Accepts both ISO 8601 date strings and numeric UNIX timestamps.
+   */
+  public static parseTimestamp(value: string): string {
+    if (/^\d+$/.test(value)) {
+      return value;
+    }
+    const ms = new Date(value).getTime();
+    if (isNaN(ms)) {
+      throw new Error(`Invalid date: ${value}`);
+    }
+    return String(Math.floor(ms / 1000));
+  }
+}