diff --git a/CHANGELOG.md b/CHANGELOG.md
index 677e978999..027c4be048 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@
 ### Features
 
 - Dynamic sampling ([#1004](https://github.com/getsentry/sentry-dart/pull/1004))
+- Set custom measurements on transactions ([#1011](https://github.com/getsentry/sentry-dart/pull/1011))
 
 ## 6.10.0
 
diff --git a/dart/lib/sentry.dart b/dart/lib/sentry.dart
index a794cfffab..717434c8f9 100644
--- a/dart/lib/sentry.dart
+++ b/dart/lib/sentry.dart
@@ -30,4 +30,3 @@ export 'src/sentry_user_feedback.dart';
 export 'src/utils/tracing_utils.dart';
 // tracing
 export 'src/tracing.dart';
-export 'src/sentry_measurement.dart';
diff --git a/dart/lib/src/noop_sentry_span.dart b/dart/lib/src/noop_sentry_span.dart
index 79b8d258de..55cbe1261b 100644
--- a/dart/lib/src/noop_sentry_span.dart
+++ b/dart/lib/src/noop_sentry_span.dart
@@ -75,6 +75,9 @@ class NoOpSentrySpan extends ISentrySpan {
   @override
   SentryTraceHeader toSentryTrace() => _header;
 
+  @override
+  void setMeasurement(String name, num value, {SentryMeasurementUnit? unit}) {}
+
   @override
   SentryBaggageHeader? toBaggageHeader() => null;
 
diff --git a/dart/lib/src/protocol/sentry_span.dart b/dart/lib/src/protocol/sentry_span.dart
index 6aeae4565a..bad87759b9 100644
--- a/dart/lib/src/protocol/sentry_span.dart
+++ b/dart/lib/src/protocol/sentry_span.dart
@@ -183,6 +183,15 @@ class SentrySpan extends ISentrySpan {
         sampled: samplingDecision?.sampled,
       );
 
+  @override
+  void setMeasurement(
+    String name,
+    num value, {
+    SentryMeasurementUnit? unit,
+  }) {
+    _tracer.setMeasurement(name, value, unit: unit);
+  }
+
   @override
   SentryBaggageHeader? toBaggageHeader() => _tracer.toBaggageHeader();
 
diff --git a/dart/lib/src/protocol/sentry_transaction.dart b/dart/lib/src/protocol/sentry_transaction.dart
index 1b7c6947cb..74f30ea67a 100644
--- a/dart/lib/src/protocol/sentry_transaction.dart
+++ b/dart/lib/src/protocol/sentry_transaction.dart
@@ -11,7 +11,7 @@ class SentryTransaction extends SentryEvent {
   static const String _type = 'transaction';
   late final List<SentrySpan> spans;
   final SentryTracer _tracer;
-  late final List<SentryMeasurement> measurements;
+  late final Map<String, SentryMeasurement> measurements;
   late final SentryTransactionInfo? transactionInfo;
 
   SentryTransaction(
@@ -33,7 +33,7 @@ class SentryTransaction extends SentryEvent {
     SdkVersion? sdk,
     SentryRequest? request,
     String? type,
-    List<SentryMeasurement>? measurements,
+    Map<String, SentryMeasurement>? measurements,
     SentryTransactionInfo? transactionInfo,
   }) : super(
           eventId: eventId,
@@ -58,7 +58,7 @@ class SentryTransaction extends SentryEvent {
 
     final spanContext = _tracer.context;
     spans = _tracer.children;
-    this.measurements = measurements ?? [];
+    this.measurements = measurements ?? {};
 
     this.contexts.trace = spanContext.toTraceContext(
       sampled: _tracer.samplingDecision?.sampled,
@@ -81,8 +81,8 @@ class SentryTransaction extends SentryEvent {
 
     if (measurements.isNotEmpty) {
       final map = <String, dynamic>{};
-      for (final measurement in measurements) {
-        map[measurement.name] = measurement.toJson();
+      for (final item in measurements.entries) {
+        map[item.key] = item.value.toJson();
       }
       json['measurements'] = map;
     }
@@ -127,7 +127,7 @@ class SentryTransaction extends SentryEvent {
     List<SentryException>? exceptions,
     List<SentryThread>? threads,
     String? type,
-    List<SentryMeasurement>? measurements,
+    Map<String, SentryMeasurement>? measurements,
     SentryTransactionInfo? transactionInfo,
   }) =>
       SentryTransaction(
@@ -150,9 +150,7 @@ class SentryTransaction extends SentryEvent {
         sdk: sdk ?? this.sdk,
         request: request ?? this.request,
         type: type ?? this.type,
-        measurements: (measurements != null
-                ? List<SentryMeasurement>.from(measurements)
-                : null) ??
+        measurements: (measurements != null ? Map.from(measurements) : null) ??
             this.measurements,
         transactionInfo: transactionInfo ?? this.transactionInfo,
       );
diff --git a/dart/lib/src/sentry_measurement.dart b/dart/lib/src/sentry_measurement.dart
index 43a2ac18bd..d7c568ee29 100644
--- a/dart/lib/src/sentry_measurement.dart
+++ b/dart/lib/src/sentry_measurement.dart
@@ -1,34 +1,52 @@
+import 'sentry_measurement_unit.dart';
+
 class SentryMeasurement {
-  SentryMeasurement(this.name, this.value);
+  SentryMeasurement(
+    this.name,
+    this.value, {
+    this.unit,
+  });
 
   /// Amount of frames drawn during a transaction
-  SentryMeasurement.totalFrames(this.value) : name = 'frames_total';
+  SentryMeasurement.totalFrames(this.value)
+      : name = 'frames_total',
+        unit = SentryMeasurementUnit.none;
 
   /// Amount of slow frames drawn during a transaction.
   /// A slow frame is any frame longer than 1s / refreshrate.
   /// So for example any frame slower than 16ms for a refresh rate of 60hz.
-  SentryMeasurement.slowFrames(this.value) : name = 'frames_slow';
+  SentryMeasurement.slowFrames(this.value)
+      : name = 'frames_slow',
+        unit = SentryMeasurementUnit.none;
 
   /// Amount of frozen frames drawn during a transaction.
   /// Typically defined as frames slower than 500ms.
-  SentryMeasurement.frozenFrames(this.value) : name = 'frames_frozen';
+  SentryMeasurement.frozenFrames(this.value)
+      : name = 'frames_frozen',
+        unit = SentryMeasurementUnit.none;
 
+  /// Duration of the Cold App start in milliseconds
   SentryMeasurement.coldAppStart(Duration duration)
       : assert(!duration.isNegative),
         name = 'app_start_cold',
-        value = duration.inMilliseconds;
+        value = duration.inMilliseconds,
+        unit = SentryMeasurementUnit.milliSecond;
 
+  /// Duration of the Warm App start in milliseconds
   SentryMeasurement.warmAppStart(Duration duration)
       : assert(!duration.isNegative),
         name = 'app_start_warm',
-        value = duration.inMilliseconds;
+        value = duration.inMilliseconds,
+        unit = SentryMeasurementUnit.milliSecond;
 
   final String name;
   final num value;
+  final SentryMeasurementUnit? unit;
 
   Map<String, dynamic> toJson() {
-    return <String, num>{
+    return <String, dynamic>{
       'value': value,
+      if (unit != null) 'unit': unit?.toStringValue(),
     };
   }
 }
diff --git a/dart/lib/src/sentry_measurement_unit.dart b/dart/lib/src/sentry_measurement_unit.dart
new file mode 100644
index 0000000000..e53432b827
--- /dev/null
+++ b/dart/lib/src/sentry_measurement_unit.dart
@@ -0,0 +1,53 @@
+enum SentryMeasurementUnit {
+  /// Nanosecond (`"nanosecond"`), 10^-9 seconds.
+  nanoSecond,
+
+  /// Microsecond (`"microsecond"`), 10^-6 seconds.
+  microSecond,
+
+  /// Millisecond (`"millisecond"`), 10^-3 seconds.
+  milliSecond,
+
+  /// Full second (`"second"`).
+  second,
+
+  /// Minute (`"minute"`), 60 seconds.
+  minute,
+
+  /// Hour (`"hour"`), 3600 seconds.
+  hour,
+
+  /// Day (`"day"`), 86,400 seconds.
+  day,
+
+  /// Week (`"week"`), 604,800 seconds.
+  week,
+
+  /// Untyped value without a unit.
+  none,
+}
+
+extension SentryMeasurementUnitExtension on SentryMeasurementUnit {
+  String toStringValue() {
+    switch (this) {
+      case SentryMeasurementUnit.nanoSecond:
+        return 'nanosecond';
+      case SentryMeasurementUnit.microSecond:
+        return 'microsecond';
+      case SentryMeasurementUnit.milliSecond:
+        return 'millisecond';
+      case SentryMeasurementUnit.second:
+        return 'second';
+      case SentryMeasurementUnit.minute:
+        return 'minute';
+      case SentryMeasurementUnit.hour:
+        return 'hour';
+      case SentryMeasurementUnit.day:
+        return 'day';
+      case SentryMeasurementUnit.week:
+        return 'week';
+      case SentryMeasurementUnit.none:
+        return 'none';
+    }
+  }
+}
diff --git a/dart/lib/src/sentry_span_interface.dart b/dart/lib/src/sentry_span_interface.dart
index 3b94613991..74d55570d2 100644
--- a/dart/lib/src/sentry_span_interface.dart
+++ b/dart/lib/src/sentry_span_interface.dart
@@ -57,6 +57,13 @@ abstract class ISentrySpan {
   /// Returns the trace information that could be sent as a sentry-trace header.
   SentryTraceHeader toSentryTrace();
 
+  /// Set observed measurement for this transaction.
+  void setMeasurement(
+    String name,
+    num value, {
+    SentryMeasurementUnit? unit,
+  });
+
   /// Returns the baggage that can be sent as "baggage" header.
   @experimental
   SentryBaggageHeader? toBaggageHeader();
diff --git a/dart/lib/src/sentry_tracer.dart b/dart/lib/src/sentry_tracer.dart
index 3982865ffb..f81d14c1fb 100644
--- a/dart/lib/src/sentry_tracer.dart
+++ b/dart/lib/src/sentry_tracer.dart
@@ -16,7 +16,7 @@ class SentryTracer extends ISentrySpan {
   late final SentrySpan _rootSpan;
   final List<SentrySpan> _children = [];
   final Map<String, dynamic> _extra = {};
-  final List<SentryMeasurement> _measurements = [];
+  final Map<String, SentryMeasurement> _measurements = {};
 
   Timer? _autoFinishAfterTimer;
   Function(SentryTracer)? _onFinish;
@@ -264,12 +264,9 @@ class SentryTracer extends ISentrySpan {
   @override
   SentryTraceHeader toSentryTrace() => _rootSpan.toSentryTrace();
 
-  void addMeasurements(List<SentryMeasurement> measurements) {
-    _measurements.addAll(measurements);
-  }
-
   @visibleForTesting
-  List<SentryMeasurement> get measurements => _measurements;
+  Map<String, SentryMeasurement> get measurements =>
+      Map.unmodifiable(_measurements);
 
   bool _haveAllChildrenFinished() {
     for (final child in children) {
@@ -285,6 +282,12 @@ class SentryTracer extends ISentrySpan {
       !span.startTimestamp
           .isAfter((span.endTimestamp ?? endTimestampCandidate));
 
+  @override
+  void setMeasurement(String name, num value, {SentryMeasurementUnit? unit}) {
+    final measurement = SentryMeasurement(name, value, unit: unit);
+    _measurements[name] = measurement;
+  }
+
   @override
   SentryBaggageHeader? toBaggageHeader() {
     final context = traceContext();
diff --git a/dart/lib/src/tracing.dart b/dart/lib/src/tracing.dart
index 0b7649d2d3..bc13c0a768 100644
--- a/dart/lib/src/tracing.dart
+++ b/dart/lib/src/tracing.dart
@@ -4,5 +4,7 @@ export 'sentry_span_context.dart';
 export 'sentry_span_interface.dart';
 export 'noop_sentry_span.dart';
 export 'invalid_sentry_trace_header_exception.dart';
+export 'sentry_measurement.dart';
+export 'sentry_measurement_unit.dart';
 export 'sentry_trace_context_header.dart';
 export 'sentry_traces_sampling_decision.dart';
diff --git a/dart/test/sentry_measurement_test.dart b/dart/test/sentry_measurement_test.dart
new file mode 100644
index 0000000000..144a8f9b7f
--- /dev/null
+++ b/dart/test/sentry_measurement_test.dart
@@ -0,0 +1,42 @@
+import 'package:collection/collection.dart';
+import 'package:sentry/sentry.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('$SentryMeasurement', () {
+    test('total frames has none unit', () {
+      expect(
+          SentryMeasurement.totalFrames(10).unit, SentryMeasurementUnit.none);
+    });
+
+    test('slow frames has none unit', () {
+      expect(SentryMeasurement.slowFrames(10).unit, SentryMeasurementUnit.none);
+    });
+
+    test('frozen frames has none unit', () {
+      expect(
+          SentryMeasurement.frozenFrames(10).unit, SentryMeasurementUnit.none);
+    });
+
+    test('warm start has milliseconds unit', () {
+      expect(SentryMeasurement.warmAppStart(Duration(seconds: 1)).unit,
+          SentryMeasurementUnit.milliSecond);
+    });
+
+    test('cold start has milliseconds unit', () {
+      expect(SentryMeasurement.coldAppStart(Duration(seconds: 1)).unit,
+          SentryMeasurementUnit.milliSecond);
+    });
+
+    test('toJson sets unit if given', () {
+      final measurement = SentryMeasurement('name', 10,
+          unit: SentryMeasurementUnit.milliSecond);
+      final map = <String, dynamic>{
+        'value': 10,
+        'unit': 'millisecond',
+      };
+
+      expect(MapEquality().equals(measurement.toJson(), map), true);
+    });
+  });
+}
diff --git a/flutter/lib/src/event_processor/native_app_start_event_processor.dart b/flutter/lib/src/event_processor/native_app_start_event_processor.dart
index 4affebb40e..298e8f3808 100644
--- a/flutter/lib/src/event_processor/native_app_start_event_processor.dart
+++ b/flutter/lib/src/event_processor/native_app_start_event_processor.dart
@@ -40,7 +40,7 @@ class NativeAppStartEventProcessor extends EventProcessor {
       if (measurement.value >= _maxAppStartMillis) {
         return event;
       }
-      event.measurements.add(measurement);
+      event.measurements[measurement.name] = measurement;
     }
     return event;
   }
diff --git a/flutter/lib/src/navigation/sentry_navigator_observer.dart b/flutter/lib/src/navigation/sentry_navigator_observer.dart
index b4bdb63cc3..b32d18e1ae 100644
--- a/flutter/lib/src/navigation/sentry_navigator_observer.dart
+++ b/flutter/lib/src/navigation/sentry_navigator_observer.dart
@@ -186,7 +186,15 @@ class SentryNavigatorObserver extends RouteObserver<PageRoute<dynamic>> {
           final nativeFrames = await _native
               .endNativeFramesCollection(transaction.context.traceId);
           if (nativeFrames != null) {
-            transaction.addMeasurements(nativeFrames.toMeasurements());
+            final measurements = nativeFrames.toMeasurements();
+            for (final item in measurements.entries) {
+              final measurement = item.value;
+              transaction.setMeasurement(
+                item.key,
+                measurement.value,
+                unit: measurement.unit,
+              );
+            }
           }
         }
       },
@@ -278,11 +286,14 @@ class RouteObserverBreadcrumb extends Breadcrumb {
 }
 
 extension NativeFramesMeasurement on NativeFrames {
-  List<SentryMeasurement> toMeasurements() {
-    return [
-      SentryMeasurement.totalFrames(totalFrames),
-      SentryMeasurement.slowFrames(slowFrames),
-      SentryMeasurement.frozenFrames(frozenFrames),
-    ];
+  Map<String, SentryMeasurement> toMeasurements() {
+    final total = SentryMeasurement.totalFrames(totalFrames);
+    final slow = SentryMeasurement.slowFrames(slowFrames);
+    final frozen = SentryMeasurement.frozenFrames(frozenFrames);
+    return {
+      total.name: total,
+      slow.name: slow,
+      frozen.name: frozen,
+    };
   }
 }
diff --git a/flutter/test/integrations/native_app_start_integration_test.dart b/flutter/test/integrations/native_app_start_integration_test.dart
index 4ca72808e8..ef851af6ac 100644
--- a/flutter/test/integrations/native_app_start_integration_test.dart
+++ b/flutter/test/integrations/native_app_start_integration_test.dart
@@ -35,9 +35,9 @@ void main() {
       final processor = fixture.options.eventProcessors.first;
       final enriched = await processor.apply(transaction) as SentryTransaction;
 
-      final expected = SentryMeasurement('app_start_cold', 10);
-      expect(enriched.measurements[0].name, expected.name);
-      expect(enriched.measurements[0].value, expected.value);
+      final measurement = enriched.measurements['app_start_cold']!;
+      expect(measurement.value, 10);
+      expect(measurement.unit, SentryMeasurementUnit.milliSecond);
     });
 
     test('native app start measurement not added to following transactions',
@@ -69,7 +69,7 @@ void main() {
 
       final tracer = fixture.createTracer();
       final transaction = SentryTransaction(tracer).copyWith();
-      transaction.measurements.add(measurement);
+      transaction.measurements[measurement.name] = measurement;
 
       final processor = fixture.options.eventProcessors.first;
 
@@ -77,7 +77,7 @@ void main() {
       var secondEnriched = await processor.apply(enriched) as SentryTransaction;
 
       expect(secondEnriched.measurements.length, 2);
-      expect(secondEnriched.measurements.contains(measurement), true);
+      expect(secondEnriched.measurements.containsKey(measurement.name), true);
     });
 
     test('native app start measurement not added if more than 60s', () async {
diff --git a/flutter/test/mocks.mocks.dart b/flutter/test/mocks.mocks.dart
index 83c9448f5a..9bce2502a0 100644
--- a/flutter/test/mocks.mocks.dart
+++ b/flutter/test/mocks.mocks.dart
@@ -28,6 +28,7 @@ import 'mocks.dart' as _i12;
 // ignore_for_file: unnecessary_parenthesis
 // ignore_for_file: camel_case_types
 // ignore_for_file: subtype_of_sealed_class
+// ignore_for_file: invalid_use_of_internal_member
 
 class _FakeSentrySpanContext_0 extends _i1.SmartFake
     implements _i2.SentrySpanContext {
@@ -144,7 +145,6 @@ class MockTransport extends _i1.Mock implements _i2.Transport {
 /// A class which mocks [SentryTracer].
 ///
 /// See the documentation for Mockito's code generation for more information.
-// ignore: invalid_use_of_internal_member
 class MockSentryTracer extends _i1.Mock implements _i8.SentryTracer {
   MockSentryTracer() {
     _i1.throwOnMissingStub(this);
@@ -232,10 +232,10 @@ class MockSentryTracer extends _i1.Mock implements _i8.SentryTracer {
         returnValue: <String, String>{},
       ) as Map<String, String>);
   @override
-  List<_i2.SentryMeasurement> get measurements => (super.noSuchMethod(
+  Map<String, _i2.SentryMeasurement> get measurements => (super.noSuchMethod(
         Invocation.getter(#measurements),
-        returnValue: <_i2.SentryMeasurement>[],
-      ) as List<_i2.SentryMeasurement>);
+        returnValue: <String, _i2.SentryMeasurement>{},
+      ) as Map<String, _i2.SentryMeasurement>);
   @override
   _i6.Future<void> finish({
     _i3.SpanStatus? status,
@@ -375,11 +375,19 @@ class MockSentryTracer extends _i1.Mock implements _i8.SentryTracer {
         ),
       ) as _i3.SentryTraceHeader);
   @override
-  void addMeasurements(List<_i2.SentryMeasurement>? measurements) =>
+  void setMeasurement(
+    String? name,
+    num? value, {
+    _i2.SentryMeasurementUnit? unit,
+  }) =>
       super.noSuchMethod(
         Invocation.method(
-          #addMeasurements,
-          [measurements],
+          #setMeasurement,
+          [
+            name,
+            value,
+          ],
+          {#unit: unit},
         ),
         returnValueForMissingStub: null,
       );
diff --git a/flutter/test/sentry_navigator_observer_test.dart b/flutter/test/sentry_navigator_observer_test.dart
index e7ffa83d28..205ddb7ac0 100644
--- a/flutter/test/sentry_navigator_observer_test.dart
+++ b/flutter/test/sentry_navigator_observer_test.dart
@@ -96,7 +96,7 @@ void main() {
 
       expect(mockNativeChannel.numberOfEndNativeFramesCalls, 1);
 
-      final measurements = actualTransaction?.measurements ?? [];
+      final measurements = actualTransaction?.measurements ?? {};
 
       expect(measurements.length, 3);
 
@@ -104,7 +104,8 @@ void main() {
       final expectedSlow = SentryMeasurement.slowFrames(2);
       final expectedFrozen = SentryMeasurement.frozenFrames(1);
 
-      for (final measurement in measurements) {
+      for (final item in measurements.entries) {
+        final measurement = item.value;
         if (measurement.name == expectedTotal.name) {
           expect(measurement.value, expectedTotal.value);
         } else if (measurement.name == expectedSlow.name) {