diff --git a/ext/openssl/extconf.rb b/ext/openssl/extconf.rb
index a897c86b6..b2eef485b 100644
--- a/ext/openssl/extconf.rb
+++ b/ext/openssl/extconf.rb
@@ -159,6 +159,7 @@ def find_openssl_library
 have_func("EVP_MD_CTX_get_pkey_ctx(NULL)", evp_h)
 have_func("EVP_PKEY_eq(NULL, NULL)", evp_h)
 have_func("EVP_PKEY_dup(NULL)", evp_h)
+have_func("EVP_PKEY_get_size", evp_h)
 
 # added in 3.2.0
 have_func("SSL_get0_group_name(NULL)", ssl_h)
diff --git a/ext/openssl/openssl_missing.h b/ext/openssl/openssl_missing.h
index 6592f9cce..331e3cec9 100644
--- a/ext/openssl/openssl_missing.h
+++ b/ext/openssl/openssl_missing.h
@@ -29,4 +29,8 @@
 #  define EVP_PKEY_eq(a, b) EVP_PKEY_cmp(a, b)
 #endif
 
+#ifndef HAVE_EVP_PKEY_GET_SIZE
+#  define EVP_PKEY_get_size(x) EVP_PKEY_size(x)
+#endif
+
 #endif /* _OSSL_OPENSSL_MISSING_H_ */
diff --git a/ext/openssl/ossl_pkey.c b/ext/openssl/ossl_pkey.c
index d2fd5b29c..fafc1d44b 100644
--- a/ext/openssl/ossl_pkey.c
+++ b/ext/openssl/ossl_pkey.c
@@ -1074,6 +1074,28 @@ ossl_pkey_compare(VALUE self, VALUE other)
         ossl_raise(ePKeyError, "EVP_PKEY_eq");
 }
 
+/*
+ *  call-seq:
+ *      pkey.size -> integer
+ *
+ * Get the key size in bytes
+ *
+ * == Example
+ *   rsa_key = OpenSSL::PKey::RSA.new(pem_encoded_private_key)
+ *
+ *   rsa_key.size => 512
+ */
+static VALUE
+ossl_pkey_size(VALUE self) {
+    int ret = 0;
+    EVP_PKEY *selfPKey;
+
+    GetPKey(self, selfPKey);
+    ret = EVP_PKEY_get_size(selfPKey);
+
+    return INT2NUM(ret);
+}
+
 /*
  * call-seq:
  *    pkey.sign(digest, data [, options]) -> string
@@ -1760,6 +1782,7 @@ Init_ossl_pkey(void)
     rb_define_method(cPKey, "raw_private_key", ossl_pkey_raw_private_key, 0);
     rb_define_method(cPKey, "raw_public_key", ossl_pkey_raw_public_key, 0);
     rb_define_method(cPKey, "compare?", ossl_pkey_compare, 1);
+    rb_define_method(cPKey, "size", ossl_pkey_size, 0);
 
     rb_define_method(cPKey, "sign", ossl_pkey_sign, -1);
     rb_define_method(cPKey, "verify", ossl_pkey_verify, -1);
diff --git a/test/openssl/test_pkey.rb b/test/openssl/test_pkey.rb
index 88299888f..d8c69c581 100644
--- a/test/openssl/test_pkey.rb
+++ b/test/openssl/test_pkey.rb
@@ -310,6 +310,20 @@ def test_compare?
     end
   end
 
+  def test_size
+    key1 = Fixtures.pkey("rsa-1")
+    key2 = Fixtures.pkey("rsa-2")
+    key3 = Fixtures.pkey("p256")
+
+    assert_equal(512, key1.size)
+    assert_equal(512, key2.size)
+    assert_equal(72, key3.size)
+
+    # Should match the number of bits of the public component for RSA keys
+    assert_equal(key1.n.num_bits / 8, key1.size)
+    assert_equal(key1.n.num_bits / 8, key2.size)
+  end
+
   def test_to_text
     rsa = Fixtures.pkey("rsa-1")
     assert_include rsa.to_text, "publicExponent"