diff --git a/README.rst b/README.rst
index 6a82944..754c5db 100644
--- a/README.rst
+++ b/README.rst
@@ -213,7 +213,8 @@ Fine-tuning Tesseract/Ghostscript/others
 
 You can specify Tesseract and Ghostscript executable locations manually, as
 well as the number of concurrent processes allowed during preprocessing and
-tesseract.  Use the following in your configuration file:
+tesseract. Defaults to the number of CPUs available. Use the following in
+your configuration file:
 
 ::
 
diff --git a/pypdfocr/pypdfocr_gs.py b/pypdfocr/pypdfocr_gs.py
index 5599082..22f9bc2 100644
--- a/pypdfocr/pypdfocr_gs.py
+++ b/pypdfocr/pypdfocr_gs.py
@@ -39,7 +39,7 @@ def __init__(self, config):
                 'GS_OUTDATED': 'Your Ghostscript version is probably out of date.  Please upgrade to the latest version',
                 'GS_MISSING_BINARY': 'Could not find Ghostscript in the usual place; please specify it using your config file',
             }
-        self.threads = config.get('threads',4)
+        self.threads = config.get('threads', os.cpu_count())
 
         if "binary" in config:  # Override location of binary
             binary = config['binary']
diff --git a/pypdfocr/pypdfocr_preprocess.py b/pypdfocr/pypdfocr_preprocess.py
index e942cc3..9d56ec7 100644
--- a/pypdfocr/pypdfocr_preprocess.py
+++ b/pypdfocr/pypdfocr_preprocess.py
@@ -44,7 +44,7 @@ def __init__(self, config):
         self.msgs = {
                 'CV_FAILED': 'convert execution failed',
             }
-        self.threads = config.get('threads', 4)
+        self.threads = config.get('threads', os.cpu_count())
 
     def _warn(self, msg): # pragma: no cover
         print("WARNING: %s" % msg)
diff --git a/pypdfocr/pypdfocr_tesseract.py b/pypdfocr/pypdfocr_tesseract.py
index 8f246ee..ffd264a 100644
--- a/pypdfocr/pypdfocr_tesseract.py
+++ b/pypdfocr/pypdfocr_tesseract.py
@@ -46,7 +46,7 @@ def __init__(self, config):
         """
         self.lang = 'eng'
         self.required = "3.02.02"
-        self.threads = config.get('threads',4)
+        self.threads = config.get('threads', os.cpu_count())
 
         if "binary" in config:  # Override location of binary
             binary = config['binary']