diff --git a/lib/node/rpc.js b/lib/node/rpc.js
index 905e84dae..6871924bf 100644
--- a/lib/node/rpc.js
+++ b/lib/node/rpc.js
@@ -604,6 +604,8 @@ class RPC extends RPCBase {
     if (help || args.length !== 0)
       throw new RPCError(errs.MISC_ERROR, 'getblockchaininfo');
 
+    const sizes = await this.getBlockchainSizes();
+
     return {
       chain: this.network.type !== 'testnet'
         ? this.network.type
@@ -621,7 +623,85 @@ class RPC extends RPCBase {
       deflationary: this.chain.height >= this.network.deflationHeight,
       pruneheight: this.chain.options.prune
         ? Math.max(0, this.chain.height - this.network.block.keepBlocks)
-        : null
+        : null,
+      size_on_disk: sizes.blockchain,
+      sizes: sizes
+    };
+  }
+
+  async getBlockchainSizes() {
+    const fs = require('bfile');
+    const path = require('path');
+
+    /**
+     * Get directory size recursively
+     * @param {String} dirPath - Directory path
+     * @returns {Promise<Number>} - Size in bytes
+     */
+    async function getDirectorySize(dirPath) {
+      let totalSize = 0;
+
+      try {
+        const stat = await fs.stat(dirPath);
+
+        if (!stat.isDirectory()) {
+          return stat.size;
+        }
+
+        const items = await fs.readdir(dirPath);
+
+        for (const item of items) {
+          const itemPath = path.join(dirPath, item);
+          const itemStat = await fs.stat(itemPath);
+
+          if (itemStat.isDirectory()) {
+            totalSize += await getDirectorySize(itemPath);
+          } else {
+            totalSize += itemStat.size;
+          }
+        }
+      } catch (e) {
+        // Directory doesn't exist or can't be accessed
+        return 0;
+      }
+
+      return totalSize;
+    }
+
+    const prefix = this.chain.options.prefix;
+    const spv = this.chain.options.spv;
+
+    let blockchain = 0;
+    let tree = 0;
+    let total = 0;
+
+    // Calculate blockchain size (blocks + chain or spvchain)
+    if (spv) {
+      // SPV mode: only spvchain directory
+      const spvchainPath = path.join(prefix, 'spvchain');
+      blockchain = await getDirectorySize(spvchainPath);
+    } else {
+      // Full node: blocks + chain directories
+      const blocksPath = path.join(prefix, 'blocks');
+      const chainPath = path.join(prefix, 'chain');
+
+      blockchain = await getDirectorySize(blocksPath) +
+                   await getDirectorySize(chainPath);
+    }
+
+    // Calculate tree size (not included in size_on_disk for full nodes)
+    if (!spv) {
+      const treePath = path.join(prefix, 'tree');
+      tree = await getDirectorySize(treePath);
+    }
+
+    // Calculate total size blockchain + tree
+    total = blockchain + tree;
+
+    return {
+      blockchain: blockchain,
+      tree: tree,
+      total: total
     };
   }
 
diff --git a/test/node-rpc-test.js b/test/node-rpc-test.js
index 9701d4398..646e69c50 100644
--- a/test/node-rpc-test.js
+++ b/test/node-rpc-test.js
@@ -54,6 +54,17 @@ describe('RPC', function() {
       assert.strictEqual(info.blocks, 0);
       assert.strictEqual(info.headers, 0);
       assert.strictEqual(info.pruned, false);
+
+      // Check new size fields
+      assert(typeof info.size_on_disk === 'number');
+      assert(info.size_on_disk >= 0);
+      assert(info.sizes);
+      assert(typeof info.sizes.blockchain === 'number');
+      assert(typeof info.sizes.tree === 'number');
+      assert(typeof info.sizes.total === 'number');
+      assert(info.sizes.blockchain >= 0);
+      assert(info.sizes.tree >= 0);
+      assert(info.sizes.total >= 0);
     });
   });