diff --git a/circuits/proof-builder/src/lib.rs b/circuits/proof-builder/src/lib.rs
index f14a7c50..0fd9e2bd 100644
--- a/circuits/proof-builder/src/lib.rs
+++ b/circuits/proof-builder/src/lib.rs
@@ -70,6 +70,22 @@ pub enum ProofRequest {
     },
 }
 
+/// Latest EL block time in the state-chain batch (max header timestamp), Unix seconds.
+///
+/// Used for `total_time_to_proof` as (time when proving completes) − (latest proved block time);
+/// see <https://github.com/GOATNetwork/bitvm2-node/issues/366>.
+pub fn state_chain_el_anchor_unix_secs(ctx: &ProofRequest) -> anyhow::Result<i64> {
+    let ProofRequest::StateChainProofRequest { blocks, .. } = ctx else {
+        anyhow::bail!("expected state chain proof request");
+    };
+    let max_ts = blocks
+        .iter()
+        .map(|b| b.evm_block.current_block.header.timestamp)
+        .max()
+        .ok_or_else(|| anyhow::anyhow!("state chain batch has no blocks"))?;
+    i64::try_from(max_ts).map_err(|_| anyhow::anyhow!("EL block timestamp out of range for i64"))
+}
+
 #[derive(Error, Debug, Clone)]
 pub enum ProofError {
     #[error("Retry after {0} seconds")]
diff --git a/proof-builder-rpc/src/task/mod.rs b/proof-builder-rpc/src/task/mod.rs
index 09eb425a..66f20dce 100644
--- a/proof-builder-rpc/src/task/mod.rs
+++ b/proof-builder-rpc/src/task/mod.rs
@@ -607,6 +607,8 @@ pub(crate) async fn update_long_running_task(
     chain_name: String,
     proving_time: i64,
     zkm_version: String,
+    // Unix seconds of the latest EL block in the proved batch (chain time anchor for issue #366).
+    el_block_anchor_unix_secs: i64,
 ) -> anyhow::Result<u64> {
     let mut storage_processor = local_db.acquire().await?;
     let task = storage_processor
@@ -617,7 +619,10 @@ pub(crate) async fn update_long_running_task(
             "Long running task not found for chain: {chain_name}, start_index: {start_index}"
         );
     }
-    let total_time_to_proof = (current_time_secs() - task.unwrap().created_at) * 1000;
+    let proving_at = current_time_secs();
+    let total_time_to_proof = proving_at
+        .saturating_sub(el_block_anchor_unix_secs)
+        .saturating_mul(1000);
     Ok(storage_processor
         .update_long_running_task_proof_success(
             start_index,
diff --git a/proof-builder-rpc/src/task/state_chain_proof.rs b/proof-builder-rpc/src/task/state_chain_proof.rs
index 5f7302bd..8a62ce55 100644
--- a/proof-builder-rpc/src/task/state_chain_proof.rs
+++ b/proof-builder-rpc/src/task/state_chain_proof.rs
@@ -2,7 +2,7 @@ use crate::task::ProofState::{Failed, New, Proven, Proving};
 use crate::task::fetch_latest_long_running_task_by_state;
 use crate::task::{create_long_running_task, update_long_running_task};
 use crate::{ProofBuilderConfig, task::fetch_latest_long_running_task};
-use proof_builder::{ProofBuilder, ProofRequest};
+use proof_builder::{state_chain_el_anchor_unix_secs, ProofBuilder, ProofRequest};
 use state_chain_proof::{StateChainProofBuilder, fetch_state_chain};
 use std::time::Duration;
 use store::localdb::LocalDB;
@@ -162,6 +162,14 @@ async fn spawn_state_chain_prover(
                     }
                 };
 
+                let el_anchor = match state_chain_el_anchor_unix_secs(&ctx) {
+                    Ok(s) => s,
+                    Err(e) => {
+                        tracing::error!("EL block anchor for total_time_to_proof: {e:?}");
+                        continue;
+                    }
+                };
+
                 let affteced = match update_long_running_task(
                     &local_db,
                     start_index as i64,
@@ -174,6 +182,7 @@ async fn spawn_state_chain_prover(
                     StateChainProofBuilder::name(),
                     0,
                     "".to_string(),
+                    el_anchor,
                 ).await {
                     Ok(affected) => affected,
                     Err(e) => {
@@ -213,6 +222,7 @@ async fn spawn_state_chain_prover(
                     StateChainProofBuilder::name(),
                     proving_time as i64,
                     zkm_version,
+                    el_anchor,
                 ).await {
                     Ok(affected) => affected,
                     Err(e) => {