diff --git a/packages/function/README.md b/packages/function/README.md
index 6e25c8e..f875174 100644
--- a/packages/function/README.md
+++ b/packages/function/README.md
@@ -238,7 +238,7 @@ console.log(result.profiling)
 // {
 //   phases: { install: 0, build: 120, spawn: 45, run: 890, total: 1055 },
 //   cpu: 234,
-//   memory: 8,
+//   memory: { total: 69996544, used: 2359296, heap: 4410880, external: 1742574 },
 //   size: 156
 // }
 ```
@@ -251,7 +251,10 @@ console.log(result.profiling)
 | `phases.run` | Time spent executing the function. |
 | `phases.total` | Wall-clock time from start to finish. |
 | `cpu` | Peak CPU time in milliseconds. |
-| `memory` | Peak memory usage in MB. |
+| `memory.total` | Resident memory of the sandbox, Node.js baseline included, in bytes. |
+| `memory.used` | Resident memory attributable to your function, in bytes. |
+| `memory.heap` | V8 heap in use, in bytes. The only field the memory limit bounds. |
+| `memory.external` | Off-heap `Buffer`/`ArrayBuffer` memory, in bytes. |
 | `size` | Bundled code size in bytes. |
 
 ### Plan limits
diff --git a/packages/function/src/index.d.ts b/packages/function/src/index.d.ts
index aaf4a7e..62de41a 100644
--- a/packages/function/src/index.d.ts
+++ b/packages/function/src/index.d.ts
@@ -10,7 +10,12 @@ export type FunctionProfiling = {
     total?: number
   }
   cpu?: number
-  memory?: number
+  memory?: {
+    total?: number
+    used?: number
+    heap?: number
+    external?: number
+  }
   size?: number
 }
 
diff --git a/packages/function/test/index.test-d.ts b/packages/function/test/index.test-d.ts
index 4f3c8a0..9cc48ba 100644
--- a/packages/function/test/index.test-d.ts
+++ b/packages/function/test/index.test-d.ts
@@ -1,3 +1,4 @@
+import { expectType } from 'tsd'
 import microlinkFn from '@microlink/function'
 
 /** response shape */
@@ -9,6 +10,12 @@ import microlinkFn from '@microlink/function'
   console.log(data.isFulfilled)
   console.log(data.profiling)
   console.log(data.logging)
+
+  /** memory is a breakdown, not a single number */
+  expectType<number | undefined>(data.profiling.memory?.total)
+  expectType<number | undefined>(data.profiling.memory?.used)
+  expectType<number | undefined>(data.profiling.memory?.heap)
+  expectType<number | undefined>(data.profiling.memory?.external)
 }
 
 /** discriminated union */