diff --git a/libc/src/stdio/printf_core/CMakeLists.txt b/libc/src/stdio/printf_core/CMakeLists.txt
--- a/libc/src/stdio/printf_core/CMakeLists.txt
+++ b/libc/src/stdio/printf_core/CMakeLists.txt
@@ -37,3 +37,17 @@
   DEPENDS
     libc.src.string.memory_utils.memset_implementation
 )
+
+add_object_library(
+  converter
+  SRCS
+    converter.cpp
+  HDRS
+    converter.h
+    converter_atlas.h
+    string_converter.h
+    char_converter.h
+  DEPENDS
+    .writer
+    .core_structs
+)
diff --git a/libc/src/stdio/printf_core/char_converter.h b/libc/src/stdio/printf_core/char_converter.h
new file mode 100644
--- /dev/null
+++ b/libc/src/stdio/printf_core/char_converter.h
@@ -0,0 +1,31 @@
+//===-- String Converter for printf -----------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdio/printf_core/core_structs.h"
+#include "src/stdio/printf_core/writer.h"
+
+namespace __llvm_libc {
+namespace printf_core {
+void convert_char(Writer *writer, FormatSection to_conv) {
+  char c = to_conv.conv_val_raw;
+
+  if (to_conv.min_width > 1) {
+    if ((to_conv.flags & FormatFlags::LEFT_JUSTIFIED) ==
+        FormatFlags::LEFT_JUSTIFIED) {
+      writer->write(&c, 1);
+      writer->write_chars(' ', to_conv.min_width - 1);
+    } else {
+      writer->write_chars(' ', to_conv.min_width - 1);
+      writer->write(&c, 1);
+    }
+  } else {
+    writer->write(&c, 1);
+  }
+}
+} // namespace printf_core
+} // namespace __llvm_libc
diff --git a/libc/src/stdio/printf_core/converter.h b/libc/src/stdio/printf_core/converter.h
--- a/libc/src/stdio/printf_core/converter.h
+++ b/libc/src/stdio/printf_core/converter.h
@@ -21,7 +21,7 @@
   Writer *writer;
 
 public:
-  Converter(Writer *writer);
+  Converter(Writer *init_writer) : writer(init_writer) {}
 
   // convert will call a conversion function to convert the FormatSection into
   // its string representation, and then that will write the result to the
diff --git a/libc/src/stdio/printf_core/converter.cpp b/libc/src/stdio/printf_core/converter.cpp
new file mode 100644
--- /dev/null
+++ b/libc/src/stdio/printf_core/converter.cpp
@@ -0,0 +1,83 @@
+//===-- Format specifier converter implmentation for printf -----*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdio/printf_core/converter.h"
+
+#include "src/stdio/printf_core/core_structs.h"
+#include "src/stdio/printf_core/writer.h"
+
+// This option allows for replacing all of the conversion functions with custom
+// replacements. This allows conversions to be replaced at compile time.
+#ifndef LLVM_LIBC_PRINTF_CONV_ATLAS
+#include "src/stdio/printf_core/converter_atlas.h"
+#else
+#include LLVM_LIBC_PRINTF_CONV_ATLAS
+#endif
+
+#include <stddef.h>
+
+namespace __llvm_libc {
+namespace printf_core {
+void Converter::convert(FormatSection to_conv) {
+  if (!to_conv.has_conv) {
+    writer->write(to_conv.raw_string, to_conv.raw_len);
+    return;
+  }
+  switch (to_conv.conv_name) {
+  case '%':
+    writer->write("%", 1);
+    return;
+  case 'c':
+    convert_char(writer, to_conv);
+    return;
+  case 's':
+    convert_string(writer, to_conv);
+    return;
+  case 'd':
+  case 'i':
+  case 'u':
+    // convert_int(writer, to_conv);
+    return;
+  case 'o':
+    // convert_oct(writer, to_conv);
+    return;
+  case 'x':
+  case 'X':
+    // convert_hex(writer, to_conv);
+    return;
+  // TODO(michaelrj): add a flag to disable float point values here
+  case 'f':
+  case 'F':
+    // convert_float_decimal(writer, to_conv);
+    return;
+  case 'e':
+  case 'E':
+    // convert_float_dec_exp(writer, to_conv);
+    return;
+  case 'a':
+  case 'A':
+    // convert_float_hex_exp(writer, to_conv);
+    return;
+  case 'g':
+  case 'G':
+    // convert_float_mixed(writer, to_conv);
+    return;
+  // TODO(michaelrj): add a flag to disable writing an int here
+  case 'n':
+    // convert_write_int(writer, to_conv);
+    return;
+  case 'p':
+    // convert_pointer(writer, to_conv);
+    return;
+  default:
+    writer->write(to_conv.raw_string, to_conv.raw_len);
+    return;
+  }
+}
+} // namespace printf_core
+} // namespace __llvm_libc
diff --git a/libc/src/stdio/printf_core/converter_atlas.h b/libc/src/stdio/printf_core/converter_atlas.h
new file mode 100644
--- /dev/null
+++ b/libc/src/stdio/printf_core/converter_atlas.h
@@ -0,0 +1,37 @@
+//===-- Map of converter headers in printf ----------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// This file exists so that if the user wants to supply a custom atlas they can
+// just replace the #include, additionally it keeps the ifdefs out of the
+// converter header.
+
+#ifndef LLVM_LIBC_SRC_STDIO_PRINTF_CORE_CONVERTER_ATLAS_H
+#define LLVM_LIBC_SRC_STDIO_PRINTF_CORE_CONVERTER_ATLAS_H
+
+// defines convert_string
+#include "src/stdio/printf_core/string_converter.h"
+
+// defines convert_char
+#include "src/stdio/printf_core/char_converter.h"
+
+// defines convert_int
+// defines convert_oct
+// defines convert_hex
+
+// TODO(michaelrj): add a flag to disable float point values here
+// defines convert_float_decimal
+// defines convert_float_dec_exp
+// defines convert_float_hex_exp
+// defines convert_float_mixed
+
+// TODO(michaelrj): add a flag to disable writing an int here
+// defines convert_write_int
+
+// defines convert_pointer
+
+#endif // LLVM_LIBC_SRC_STDIO_PRINTF_CORE_CONVERTER_ATLAS_H
diff --git a/libc/src/stdio/printf_core/core_structs.h b/libc/src/stdio/printf_core/core_structs.h
--- a/libc/src/stdio/printf_core/core_structs.h
+++ b/libc/src/stdio/printf_core/core_structs.h
@@ -10,6 +10,7 @@
 #define LLVM_LIBC_SRC_STDIO_PRINTF_CORE_CORE_STRUCTS_H
 
 #include "src/__support/CPP/StringView.h"
+#include "src/__support/FPUtil/FPBits.h"
 
 #include <inttypes.h>
 #include <stddef.h>
@@ -45,7 +46,8 @@
   int min_width = 0;
   int precision = -1;
 
-  __uint128_t conv_val_raw; // Needs to be large enough to hold a long double.
+  // Needs to be large enough to hold a long double.
+  fputil::FPBits<long double>::UIntType conv_val_raw;
   void *conv_val_ptr;
 
   char conv_name;
diff --git a/libc/src/stdio/printf_core/parser.cpp b/libc/src/stdio/printf_core/parser.cpp
--- a/libc/src/stdio/printf_core/parser.cpp
+++ b/libc/src/stdio/printf_core/parser.cpp
@@ -13,6 +13,7 @@
 #include "src/__support/arg_list.h"
 
 #include "src/__support/CPP/Bit.h"
+#include "src/__support/FPUtil/FPBits.h"
 #include "src/__support/ctype_utils.h"
 #include "src/__support/str_to_integer.h"
 
@@ -120,6 +121,7 @@
         break;
       }
       break;
+      // TODO(michaelrj): add a flag to disable float point values here
     case ('f'):
     case ('F'):
     case ('e'):
@@ -132,7 +134,7 @@
         section.conv_val_raw =
             bit_cast<uint64_t>(GET_ARG_VAL_SIMPLEST(double, conv_index));
       else
-        section.conv_val_raw = bit_cast<__uint128_t>(
+        section.conv_val_raw = bit_cast<fputil::FPBits<long double>::UIntType>(
             GET_ARG_VAL_SIMPLEST(long double, conv_index));
       break;
     case ('n'):
@@ -335,6 +337,7 @@
           break;
         }
         break;
+      // TODO(michaelrj): add a flag to disable float point values here
       case ('f'):
       case ('F'):
       case ('e'):
@@ -388,6 +391,7 @@
       args_cur.next_var<uint32_t>();
     else if (cur_type_desc == TYPE_DESC<uint64_t>)
       args_cur.next_var<uint64_t>();
+    // TODO(michaelrj): add a flag to disable float point values here
     // Floating point numbers are stored separately from the other arguments.
     else if (cur_type_desc == TYPE_DESC<double>)
       args_cur.next_var<double>();
diff --git a/libc/src/stdio/printf_core/string_converter.h b/libc/src/stdio/printf_core/string_converter.h
new file mode 100644
--- /dev/null
+++ b/libc/src/stdio/printf_core/string_converter.h
@@ -0,0 +1,44 @@
+//===-- String Converter for printf -----------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdio/printf_core/core_structs.h"
+#include "src/stdio/printf_core/writer.h"
+
+#include <stddef.h>
+
+namespace __llvm_libc {
+namespace printf_core {
+void convert_string(Writer *writer, FormatSection to_conv) {
+  int string_len = 0;
+
+  for (char *cur_str = reinterpret_cast<char *>(to_conv.conv_val_ptr);
+       cur_str[string_len]; ++string_len) {
+    ;
+  }
+
+  if (to_conv.precision >= 0 && to_conv.precision < string_len)
+    string_len = to_conv.precision;
+
+  if (to_conv.min_width > string_len) {
+    if ((to_conv.flags & FormatFlags::LEFT_JUSTIFIED) ==
+        FormatFlags::LEFT_JUSTIFIED) {
+      writer->write(reinterpret_cast<const char *>(to_conv.conv_val_ptr),
+                    string_len);
+      writer->write_chars(' ', to_conv.min_width - string_len);
+    } else {
+      writer->write_chars(' ', to_conv.min_width - string_len);
+      writer->write(reinterpret_cast<const char *>(to_conv.conv_val_ptr),
+                    string_len);
+    }
+  } else {
+    writer->write(reinterpret_cast<const char *>(to_conv.conv_val_ptr),
+                  string_len);
+  }
+}
+} // namespace printf_core
+} // namespace __llvm_libc
diff --git a/libc/test/src/stdio/printf_core/CMakeLists.txt b/libc/test/src/stdio/printf_core/CMakeLists.txt
--- a/libc/test/src/stdio/printf_core/CMakeLists.txt
+++ b/libc/test/src/stdio/printf_core/CMakeLists.txt
@@ -6,6 +6,7 @@
     parser_test.cpp
   DEPENDS
     libc.src.stdio.printf_core.parser
+    libc.src.stdio.printf_core.core_structs
     libc.src.__support.arg_list
   LINK_LIBRARIES
     LibcPrintfHelpers
@@ -21,3 +22,16 @@
     libc.src.stdio.printf_core.writer
     libc.src.stdio.printf_core.string_writer
 )
+
+add_libc_unittest(
+  converter_test
+  SUITE
+    libc_stdio_unittests
+  SRCS
+    converter_test.cpp
+  DEPENDS
+    libc.src.stdio.printf_core.converter
+    libc.src.stdio.printf_core.writer
+    libc.src.stdio.printf_core.string_writer
+    libc.src.stdio.printf_core.core_structs
+)
diff --git a/libc/test/src/stdio/printf_core/converter_test.cpp b/libc/test/src/stdio/printf_core/converter_test.cpp
new file mode 100644
--- /dev/null
+++ b/libc/test/src/stdio/printf_core/converter_test.cpp
@@ -0,0 +1,202 @@
+//===-- Unittests for the printf Converter --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdio/printf_core/converter.h"
+#include "src/stdio/printf_core/core_structs.h"
+#include "src/stdio/printf_core/string_writer.h"
+#include "src/stdio/printf_core/writer.h"
+
+#include "utils/UnitTest/Test.h"
+
+TEST(LlvmLibcPrintfConverterTest, Constructor) {
+  char str[10];
+  __llvm_libc::printf_core::StringWriter str_writer(str);
+  __llvm_libc::printf_core::Writer writer(
+      reinterpret_cast<void *>(&str_writer),
+      __llvm_libc::printf_core::write_to_string);
+  __llvm_libc::printf_core::Converter converter(&writer);
+}
+
+TEST(LlvmLibcPrintfConverterTest, SimpleRawConversion) {
+  char str[10];
+  __llvm_libc::printf_core::StringWriter str_writer(str);
+  __llvm_libc::printf_core::Writer writer(
+      reinterpret_cast<void *>(&str_writer),
+      __llvm_libc::printf_core::write_to_string);
+  __llvm_libc::printf_core::Converter converter(&writer);
+
+  __llvm_libc::printf_core::FormatSection raw_section;
+  raw_section.has_conv = false;
+  raw_section.raw_string = "abc";
+  raw_section.raw_len = 3;
+
+  converter.convert(raw_section);
+
+  str_writer.terminate();
+
+  ASSERT_STREQ(str, "abc");
+  ASSERT_EQ(writer.get_chars_written(), 3ull);
+}
+
+TEST(LlvmLibcPrintfConverterTest, PercentConversion) {
+  char str[20];
+  __llvm_libc::printf_core::StringWriter str_writer(str);
+  __llvm_libc::printf_core::Writer writer(
+      reinterpret_cast<void *>(&str_writer),
+      __llvm_libc::printf_core::write_to_string);
+  __llvm_libc::printf_core::Converter converter(&writer);
+
+  __llvm_libc::printf_core::FormatSection simple_conv;
+  simple_conv.has_conv = true;
+  simple_conv.raw_string = "abc123";
+  simple_conv.raw_len = 6;
+  simple_conv.conv_name = '%';
+
+  converter.convert(simple_conv);
+
+  str[1] = '\0';
+
+  ASSERT_STREQ(str, "%");
+  ASSERT_EQ(writer.get_chars_written(), 1ull);
+}
+
+TEST(LlvmLibcPrintfConverterTest, CharConversion) {
+  char str[20];
+  __llvm_libc::printf_core::StringWriter str_writer(str);
+  __llvm_libc::printf_core::Writer writer(
+      reinterpret_cast<void *>(&str_writer),
+      __llvm_libc::printf_core::write_to_string);
+  __llvm_libc::printf_core::Converter converter(&writer);
+
+  __llvm_libc::printf_core::FormatSection simple_conv;
+  simple_conv.has_conv = true;
+  simple_conv.raw_string = "abc123";
+  simple_conv.raw_len = 6;
+  simple_conv.conv_name = 'c';
+  simple_conv.conv_val_raw = 'D';
+
+  converter.convert(simple_conv);
+
+  str[1] = '\0';
+
+  ASSERT_STREQ(str, "D");
+  ASSERT_EQ(writer.get_chars_written(), 1ull);
+
+  __llvm_libc::printf_core::FormatSection right_justified_conv;
+  right_justified_conv.has_conv = true;
+  right_justified_conv.raw_string = "abc123";
+  right_justified_conv.raw_len = 6;
+  right_justified_conv.conv_name = 'c';
+  right_justified_conv.min_width = 4;
+  right_justified_conv.conv_val_raw = 'E';
+  converter.convert(right_justified_conv);
+
+  str[5] = '\0';
+
+  ASSERT_STREQ(str, "D   E");
+  ASSERT_EQ(writer.get_chars_written(), 5ull);
+
+  __llvm_libc::printf_core::FormatSection left_justified_conv;
+  left_justified_conv.has_conv = true;
+  left_justified_conv.raw_string = "abc123";
+  left_justified_conv.raw_len = 6;
+  left_justified_conv.conv_name = 'c';
+  left_justified_conv.flags =
+      __llvm_libc::printf_core::FormatFlags::LEFT_JUSTIFIED;
+  left_justified_conv.min_width = 4;
+  left_justified_conv.conv_val_raw = 'F';
+  converter.convert(left_justified_conv);
+
+  str[9] = '\0';
+
+  ASSERT_STREQ(str, "D   EF   ");
+  ASSERT_EQ(writer.get_chars_written(), 9ull);
+}
+
+TEST(LlvmLibcPrintfConverterTest, StringConversion) {
+  char str[20];
+  __llvm_libc::printf_core::StringWriter str_writer(str);
+  __llvm_libc::printf_core::Writer writer(
+      reinterpret_cast<void *>(&str_writer),
+      __llvm_libc::printf_core::write_to_string);
+  __llvm_libc::printf_core::Converter converter(&writer);
+
+  __llvm_libc::printf_core::FormatSection simple_conv;
+  simple_conv.has_conv = true;
+  simple_conv.raw_string = "abc123";
+  simple_conv.raw_len = 6;
+  simple_conv.conv_name = 's';
+  simple_conv.conv_val_ptr = const_cast<char *>("DEF");
+
+  converter.convert(simple_conv);
+
+  str[3] = '\0'; // this null terminator is just for checking after every step.
+
+  ASSERT_STREQ(str, "DEF");
+  ASSERT_EQ(writer.get_chars_written(), 3ull);
+
+  // continuing to write to this str_writer will overwrite that null terminator.
+
+  __llvm_libc::printf_core::FormatSection high_precision_conv;
+  high_precision_conv.has_conv = true;
+  high_precision_conv.raw_string = "abc123";
+  high_precision_conv.raw_len = 6;
+  high_precision_conv.conv_name = 's';
+  high_precision_conv.precision = 4;
+  high_precision_conv.conv_val_ptr = const_cast<char *>("456");
+  converter.convert(high_precision_conv);
+
+  str[6] = '\0';
+
+  ASSERT_STREQ(str, "DEF456");
+  ASSERT_EQ(writer.get_chars_written(), 6ull);
+
+  __llvm_libc::printf_core::FormatSection low_precision_conv;
+  low_precision_conv.has_conv = true;
+  low_precision_conv.raw_string = "abc123";
+  low_precision_conv.raw_len = 6;
+  low_precision_conv.conv_name = 's';
+  low_precision_conv.precision = 2;
+  low_precision_conv.conv_val_ptr = const_cast<char *>("xyz");
+  converter.convert(low_precision_conv);
+
+  str[8] = '\0';
+
+  ASSERT_STREQ(str, "DEF456xy");
+  ASSERT_EQ(writer.get_chars_written(), 8ull);
+
+  __llvm_libc::printf_core::FormatSection right_justified_conv;
+  right_justified_conv.has_conv = true;
+  right_justified_conv.raw_string = "abc123";
+  right_justified_conv.raw_len = 6;
+  right_justified_conv.conv_name = 's';
+  right_justified_conv.min_width = 4;
+  right_justified_conv.conv_val_ptr = const_cast<char *>("789");
+  converter.convert(right_justified_conv);
+
+  str[12] = '\0';
+
+  ASSERT_STREQ(str, "DEF456xy 789");
+  ASSERT_EQ(writer.get_chars_written(), 12ull);
+
+  __llvm_libc::printf_core::FormatSection left_justified_conv;
+  left_justified_conv.has_conv = true;
+  left_justified_conv.raw_string = "abc123";
+  left_justified_conv.raw_len = 6;
+  left_justified_conv.conv_name = 's';
+  left_justified_conv.flags =
+      __llvm_libc::printf_core::FormatFlags::LEFT_JUSTIFIED;
+  left_justified_conv.min_width = 4;
+  left_justified_conv.conv_val_ptr = const_cast<char *>("ghi");
+  converter.convert(left_justified_conv);
+
+  str[16] = '\0';
+
+  ASSERT_STREQ(str, "DEF456xy 789ghi ");
+  ASSERT_EQ(writer.get_chars_written(), 16ull);
+}