diff --git a/src/remucs/__main__.py b/src/remucs/__main__.py
index 905213c..dab384e 100644
--- a/src/remucs/__main__.py
+++ b/src/remucs/__main__.py
@@ -40,6 +40,10 @@
                                default=','.join(["1"]*len(STEMS)),
                                show_default=True,
                                help=f'Gain of individual stems \"{",".join(sorted(STEMS))}\", e.g. \"2,1,0.5,0\".')
+@click.option('-a', '--a4',
+                               default=None,
+                               type=int,
+                               help='Target tuning reference frequency, to automatically estimate the pitch shifting factor (experimental).')
 @click.option('-p', '--pitch',
                                default='0',
                                show_default=True,
@@ -57,7 +61,7 @@
                                VERSION,
                                '-V', '--version',
                                message='%(version)s')
-def main(files, fine, norm, mono, bala, gain, pitch, data, quiet):
+def main(files, fine, norm, mono, bala, gain, a4, pitch, data, quiet):
 
     try:
 
@@ -72,6 +76,7 @@ def main(files, fine, norm, mono, bala, gain, pitch, data, quiet):
             mono=mono,
             bala=bala,
             gain=gain,
+            a4=a4,
             pitch=pitch)
 
         for file in list(set(files)):
diff --git a/src/remucs/options.py b/src/remucs/options.py
index 0b64a1e..2db5875 100644
--- a/src/remucs/options.py
+++ b/src/remucs/options.py
@@ -1,5 +1,5 @@
 from dataclasses import dataclass, field
-from typing import List
+from typing import List, Union
 
 
 @dataclass
@@ -14,6 +14,7 @@ class RemucsOptions:
     bala: List[float] = field(default_factory=lambda: [0]*4)
     gain: List[float] = field(default_factory=lambda: [1]*4)
 
+    a4:        Union[int, None] = None
     pitch:     float = 1
     quefrency: float = 1e-3
 
diff --git a/src/remucs/remucs.py b/src/remucs/remucs.py
index a9b2d1d..2078819 100644
--- a/src/remucs/remucs.py
+++ b/src/remucs/remucs.py
@@ -8,6 +8,7 @@
 from remucs.options import RemucsOptions
 from remucs.analysis import analyze
 from remucs.synthesis import synthesize
+from remucs.tuning import howto_shift_pitch
 
 
 def remucs(file: Union[str, PathLike], data: Union[str, PathLike] = '~', opts: Union[RemucsOptions, None] = None):
@@ -36,4 +37,10 @@ def remucs(file: Union[str, PathLike], data: Union[str, PathLike] = '~', opts: U
     dst = file.with_suffix(opts.remucs + file.suffix)
 
     analyze(src, data, opts)
+
+    if opts.a4:
+
+        file       = data / opts.model / ('other' + src.suffix)
+        opts.pitch = howto_shift_pitch(file, opts)
+
     synthesize(dst, data, opts)
diff --git a/src/remucs/tuning.py b/src/remucs/tuning.py
index 85abb9b..7d40013 100644
--- a/src/remucs/tuning.py
+++ b/src/remucs/tuning.py
@@ -61,7 +61,7 @@ def analyze(src: Path, opts: RemucsOptions) -> Tuple[NDArray, NDArray]:
     x, samplerate = resample(src, samplerate)
 
     reference  = 440
-    bandwidth  = (100, 4000)
+    bandwidth  = 100, 4000
     resolution = int(1200 / 25)
     batchsize  = int(1 * samplerate)
     numpeaks   = 3
@@ -117,3 +117,25 @@ def analyze(src: Path, opts: RemucsOptions) -> Tuple[NDArray, NDArray]:
     assert numpy.all(numpy.isfinite(weights))
 
     return estimates, weights
+
+
+def howto_shift_pitch(src: Path, opts: RemucsOptions) -> float:
+
+    estimates, weights = analyze(src, opts)
+
+    values = numpy.round(estimates).astype(int)
+    bounds = numpy.min(values), numpy.max(values)
+    bins   = numpy.arange(bounds[0], bounds[1] + 1)
+    edges  = numpy.arange(bounds[0], bounds[1] + 2) - 0.5
+    hist   = numpy.histogram(values, bins=edges, weights=weights)
+
+    assert hist[0].shape == bins.shape
+    assert hist[1].shape == edges.shape
+
+    a4 = bins[numpy.argmax(hist[0])]
+    q  = opts.a4 / a4
+
+    if not opts.quiet:
+        click.echo(f'Estimated pitch shifting factor {q} (from {a4} Hz to {opts.a4} Hz)')
+
+    return q
diff --git a/src/sandbox/tuning.py b/src/sandbox/tuning.py
index 087c4fc..bb8633d 100644
--- a/src/sandbox/tuning.py
+++ b/src/sandbox/tuning.py
@@ -32,9 +32,9 @@ def main():
     cp2, weights = analyze(test, RemucsOptions())
 
     values = np.round(cp2).astype(int)
-    minmax = np.min(values), np.max(values)
-    bins   = np.arange(minmax[0], minmax[1] + 1)
-    edges  = np.arange(minmax[0], minmax[1] + 2) - 0.5
+    bounds = np.min(values), np.max(values)
+    bins   = np.arange(bounds[0], bounds[1] + 1)
+    edges  = np.arange(bounds[0], bounds[1] + 2) - 0.5
     hist   = np.histogram(values, bins=edges, weights=weights)
 
     assert hist[0].shape == bins.shape