diff --git a/AGENTS.md b/AGENTS.md
index dc14715..784b475 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -128,8 +128,8 @@ to run non-interactively.
   - static: `--static-dir <dir>`, `--single-page-app`
 - `--framework-preset <preset>`, `--install-command`, `--build-command`,
   `--pre-deploy-command`, `--app-directory <path>`
-- `--region <region>`, `--build-timeout <minutes>`,
-  `--build-memory-limit <megabytes>`
+- `--region <region>`, `--build-timeout <duration>` (minutes, or e.g.
+  `10m`/`600s`), `--build-memory-limit <megabytes>`
 
 ### `env`
 
diff --git a/deploy/create/flow.ts b/deploy/create/flow.ts
index e707e33..612dbd1 100644
--- a/deploy/create/flow.ts
+++ b/deploy/create/flow.ts
@@ -22,6 +22,28 @@ export const AVAILABLE_BUILD_TIMEOUTS = [5, 10, 15, 20, 25, 30];
 export const AVAILABLE_BUILD_MEMORY_LIMITS = [1024, 2048, 3072, 4096];
 export const REGIONS = ["us", "eu", "global"];
 
+const DURATION_UNIT_MINUTES: Record<string, number> = {
+  s: 1 / 60,
+  m: 1,
+  h: 60,
+};
+
+/**
+ * Parses `--build-timeout`: a number of minutes (`10`, as the flag has always
+ * taken), or a whole number with a unit suffix as in deno.json (`"600s"`,
+ * `"10m"`). Returns the timeout in minutes if it is one of the available
+ * steps (5 to 30 minutes), and null otherwise.
+ */
+export function parseBuildTimeoutFlag(value: string): number | null {
+  const match = /^([1-9][0-9]*)([smh])$/.exec(value);
+  // Without a unit, convert as the flag's former numeric type did, so that
+  // spellings such as `10.0` keep working.
+  const minutes = match === null
+    ? Number(value)
+    : Number(match[1]) * DURATION_UNIT_MINUTES[match[2]];
+  return AVAILABLE_BUILD_TIMEOUTS.includes(minutes) ? minutes : null;
+}
+
 /**
  * The build timeout a detected build config asks for (deno.json
  * `deploy.buildTimeout`), as the largest available step not above it or
diff --git a/deploy/create/mod.ts b/deploy/create/mod.ts
index a9fd3ed..54e8216 100644
--- a/deploy/create/mod.ts
+++ b/deploy/create/mod.ts
@@ -6,6 +6,7 @@ import {
   AVAILABLE_BUILD_TIMEOUTS,
   createFlow,
   detectedBuildTimeoutForOrg,
+  parseBuildTimeoutFlag,
   REGIONS,
   renderBuildConfig,
 } from "./flow.ts";
@@ -126,21 +127,24 @@ export const createCommand = new Command<GlobalContext>()
       "For static configuration",
   )
   .option(
-    "--build-timeout <minutes:number>",
-    `The build timeout in minutes. One of ${
+    "--build-timeout <duration:string>",
+    `The build timeout, as minutes or with a unit suffix (e.g. 10, 10m, 600s). One of ${
       AVAILABLE_BUILD_TIMEOUTS.join(", ")
-    }. Defaults to deploy.buildTimeout from a detected deno.json, or ${
+    } minutes. Defaults to deploy.buildTimeout from a detected deno.json, or ${
       AVAILABLE_BUILD_TIMEOUTS[0]
-    }`,
+    } minutes`,
     {
-      value(value: number) {
-        if (AVAILABLE_BUILD_TIMEOUTS.includes(value)) {
-          return value;
+      value(value: string) {
+        const minutes = parseBuildTimeoutFlag(value);
+        if (minutes !== null) {
+          return minutes;
         } else {
           throw new ValidationError(
             `Invalid build timeout: ${value}. Valid values are ${
               AVAILABLE_BUILD_TIMEOUTS.join(", ")
-            }.`,
+            } minutes, e.g. ${AVAILABLE_BUILD_TIMEOUTS[1]} or ${
+              AVAILABLE_BUILD_TIMEOUTS[1]
+            }m.`,
           );
         }
       },
diff --git a/tests/build_timeout.test.ts b/tests/build_timeout.test.ts
index c60ebee..384c93c 100644
--- a/tests/build_timeout.test.ts
+++ b/tests/build_timeout.test.ts
@@ -3,6 +3,7 @@ import type { TRPCClient } from "../auth.ts";
 import {
   detectedBuildTimeout,
   detectedBuildTimeoutForOrg,
+  parseBuildTimeoutFlag,
 } from "../deploy/create/flow.ts";
 
 Deno.test("detectedBuildTimeout: undefined without a deno.json build timeout", () => {
@@ -87,3 +88,18 @@ Deno.test("detectedBuildTimeoutForOrg: leaves an unknown org uncapped for the co
     20,
   );
 });
+
+Deno.test("parseBuildTimeoutFlag: minutes, or a duration with a unit suffix", () => {
+  assertEquals(parseBuildTimeoutFlag("10"), 10);
+  assertEquals(parseBuildTimeoutFlag("10m"), 10);
+  assertEquals(parseBuildTimeoutFlag("600s"), 10);
+  assertEquals(parseBuildTimeoutFlag("30m"), 30);
+  // A unitless value converts like the flag's former numeric type.
+  assertEquals(parseBuildTimeoutFlag("10.0"), 10);
+  assertEquals(parseBuildTimeoutFlag("05"), 5);
+  for (
+    const value of ["7", "90s", "1h", "0", "10min", "1.5m", "", "-5", "05m"]
+  ) {
+    assertEquals(parseBuildTimeoutFlag(value), null, value);
+  }
+});