diff --git a/proto/anki/scheduler.proto b/proto/anki/scheduler.proto
index ea483d3db..32883624e 100644
--- a/proto/anki/scheduler.proto
+++ b/proto/anki/scheduler.proto
@@ -389,6 +389,11 @@ message FsrsReview {
   uint32 delta_t = 2;
 }
 
+enum CMRRTarget {
+  memorised = 0;
+  stability = 1;
+};
+
 message SimulateFsrsReviewRequest {
   repeated float params = 1;
   float desired_retention = 2;
@@ -402,6 +407,8 @@ message SimulateFsrsReviewRequest {
   repeated float easy_days_percentages = 10;
   deck_config.DeckConfig.Config.ReviewCardOrder review_order = 11;
   optional uint32 suspend_after_lapse_count = 12;
+  // For CMRR
+  optional CMRRTarget target = 13;
 }
 
 message SimulateFsrsReviewResponse {
diff --git a/rslib/src/scheduler/fsrs/retention.rs b/rslib/src/scheduler/fsrs/retention.rs
index 4c21623bb..b096fdccd 100644
--- a/rslib/src/scheduler/fsrs/retention.rs
+++ b/rslib/src/scheduler/fsrs/retention.rs
@@ -1,7 +1,9 @@
+use anki_proto::scheduler::CmrrTarget;
 // Copyright: Ankitects Pty Ltd and contributors
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 use anki_proto::scheduler::SimulateFsrsReviewRequest;
 use fsrs::extract_simulator_config;
+use fsrs::SimulationResult;
 use fsrs::SimulatorConfig;
 use fsrs::FSRS;
 
@@ -16,6 +18,40 @@ pub struct ComputeRetentionProgress {
 
 impl Collection {
     pub fn compute_optimal_retention(&mut self, req: SimulateFsrsReviewRequest) -> Result<f32> {
+        // Helper macro to wrap the closure for "CMRRTargetFn"s
+        macro_rules! wrap {
+            ($f:expr) => {
+                Some(fsrs::CMRRTargetFn(std::sync::Arc::new($f)))
+            };
+        }
+
+        let target = req
+            .target
+            .map(TryInto::try_into)
+            .transpose()
+            .unwrap_or(None);
+
+        let days_to_simulate = req.days_to_simulate as f32;
+
+        let target = match target {
+            Some(CmrrTarget::Memorised) => None,
+            Some(CmrrTarget::Stability) => {
+                wrap!(move |SimulationResult {
+                                cards,
+                                cost_per_day,
+                                ..
+                            },
+                            params| {
+                    let total_cost = cost_per_day.iter().sum::<f32>();
+                    total_cost
+                        / cards.iter().fold(0., |p, c| {
+                            p + (c.retention_on(params, days_to_simulate) * c.stability)
+                        })
+                })
+            }
+            None => None,
+        };
+
         let mut anki_progress = self.new_progress_handler::<ComputeRetentionProgress>();
         let fsrs = FSRS::new(None)?;
         if req.days_to_simulate == 0 {
@@ -34,7 +70,7 @@ impl Collection {
                         .is_ok()
                 },
                 Some(cards),
-                None,
+                target,
             )?
             .clamp(0.7, 0.95))
     }