diff --git a/binaries/cuprated/src/rpc/helper.rs b/binaries/cuprated/src/rpc/helper.rs
index f3b7164c..48434a45 100644
--- a/binaries/cuprated/src/rpc/helper.rs
+++ b/binaries/cuprated/src/rpc/helper.rs
@@ -8,11 +8,15 @@
 use anyhow::{anyhow, Error};
 use monero_serai::block::Block;
 
+use cuprate_consensus::{BlockChainContext, BlockChainContextService};
 use cuprate_helper::{cast::usize_to_u64, map::split_u128_into_low_high_bits};
 use cuprate_rpc_types::misc::{BlockHeader, KeyImageSpentStatus};
 use cuprate_types::ExtendedBlockHeader;
 
-use crate::{rpc::request::blockchain, rpc::CupratedRpcHandler};
+use crate::{
+    rpc::request::{blockchain, blockchain_context},
+    rpc::CupratedRpcHandler,
+};
 
 pub(super) fn into_block_header(
     height: u64,
diff --git a/binaries/cuprated/src/rpc/json.rs b/binaries/cuprated/src/rpc/json.rs
index faccde05..656bc6fa 100644
--- a/binaries/cuprated/src/rpc/json.rs
+++ b/binaries/cuprated/src/rpc/json.rs
@@ -931,20 +931,31 @@ async fn calc_pow(
     let block = Block::read(&mut block_blob.as_slice())?;
     let seed_hash = helper::hex_to_hash(request.seed_hash)?;
 
-    // let pow_hash = blockchain_manager::calculate_pow(
-    //     &mut state.blockchain_manager,
-    //     hardfork,
-    //     request.height,
-    //     block,
-    //     seed_hash,
-    // )
-    // .await?;
+    let block_weight = todo!();
 
-    // let hex = hex::encode(pow_hash);
+    let median_for_block_reward = blockchain_context::context(&mut state.blockchain_context)
+        .await?
+        .unchecked_blockchain_context()
+        .context_to_verify_block
+        .median_weight_for_block_reward;
 
-    let hex = todo!();
+    if cuprate_consensus_rules::blocks::check_block_weight(block_weight, median_for_block_reward)
+        .is_err()
+    {
+        return Err(anyhow!("Block blob size is too big, rejecting block"));
+    }
 
-    Ok(CalcPowResponse { pow_hash: hex })
+    let pow_hash = blockchain_context::calculate_pow(
+        &mut state.blockchain_context,
+        hardfork,
+        block,
+        seed_hash,
+    )
+    .await?;
+
+    let pow_hash = hex::encode(pow_hash);
+
+    Ok(CalcPowResponse { pow_hash })
 }
 
 /// <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/rpc/core_rpc_server.cpp#L3542-L3551>
diff --git a/binaries/cuprated/src/rpc/request/blockchain_context.rs b/binaries/cuprated/src/rpc/request/blockchain_context.rs
index 73ae3c0c..f0990afb 100644
--- a/binaries/cuprated/src/rpc/request/blockchain_context.rs
+++ b/binaries/cuprated/src/rpc/request/blockchain_context.rs
@@ -73,17 +73,22 @@ pub(crate) async fn fee_estimate(
 pub(crate) async fn calculate_pow(
     blockchain_context: &mut BlockChainContextService,
     hardfork: HardFork,
-    height: u64,
-    block: Box<Block>,
+    block: Block,
     seed_hash: [u8; 32],
 ) -> Result<[u8; 32], Error> {
+    let Some(height) = block.number() else {
+        return Err(anyhow!("block is missing height"));
+    };
+
+    let block = Box::new(block);
+
     let BlockChainContextResponse::CalculatePow(hash) = blockchain_context
         .ready()
         .await
         .map_err(|e| anyhow!(e))?
         .call(BlockChainContextRequest::CalculatePow {
             hardfork,
-            height: u64_to_usize(height),
+            height,
             block,
             seed_hash,
         })