diff --git a/NanoVNASaver/Formatting.py b/NanoVNASaver/Formatting.py
index b0d11f7..2f04972 100644
--- a/NanoVNASaver/Formatting.py
+++ b/NanoVNASaver/Formatting.py
@@ -36,6 +36,7 @@ FMT_REACT = SITools.Format(max_nr_digits=5, space_str=" ", allow_strip=True)
 FMT_COMPLEX = SITools.Format(max_nr_digits=3, allow_strip=True,
                              printable_min=0, unprintable_under="- ")
 FMT_COMPLEX_NEG = SITools.Format(max_nr_digits=3, allow_strip=True)
+FMT_WAVELENGTH = SITools.Format(max_nr_digits=4, space_str=" ")
 FMT_PARSE = SITools.Format(parse_sloppy_unit=True, parse_sloppy_kilo=True,
                            parse_clamp_min=0)
 
@@ -114,6 +115,9 @@ def format_complex_imp(z: complex, allow_negative: bool = False) -> str:
     im = SITools.Value(abs(z.imag), fmt=FMT_COMPLEX)
     return f"{re}{'-' if z.imag < 0 else '+'}j{im} \N{OHM SIGN}"
 
+def format_wavelength(length: Number) -> str:
+    return str(SITools.Value(length, "m", FMT_WAVELENGTH))
+
 
 def parse_frequency(freq: str) -> int:
     try:
diff --git a/NanoVNASaver/Marker/Delta.py b/NanoVNASaver/Marker/Delta.py
index e13b1b7..7488ea9 100644
--- a/NanoVNASaver/Marker/Delta.py
+++ b/NanoVNASaver/Marker/Delta.py
@@ -31,6 +31,7 @@ from NanoVNASaver.Formatting import (
     format_q_factor,
     format_resistance,
     format_vswr,
+    format_wavelength,
 )
 
 from .Widget import Marker
@@ -87,6 +88,8 @@ class DeltaMarker(Marker):
 
         self.label['actualfreq'].setText(
             format_frequency_space(s11_b.freq - s11_a.freq))
+        self.label['lambda'].setText(
+            format_wavelength(s11_b.wavelength - s11_a.wavelength))
         self.label['admittance'].setText(format_complex_imp(imp_p, True))
         self.label['impedance'].setText(format_complex_imp(imp, True))
 
diff --git a/NanoVNASaver/Marker/Values.py b/NanoVNASaver/Marker/Values.py
index ec72931..0cf4e70 100644
--- a/NanoVNASaver/Marker/Values.py
+++ b/NanoVNASaver/Marker/Values.py
@@ -30,6 +30,7 @@ class Label(NamedTuple):
 
 TYPES = (
     Label("actualfreq", "Frequency", "Actual frequency", True),
+    Label("lambda", "Wavelength", "Wavelength", False),
     Label("impedance", "Impedance", "Impedance", True),
     Label("admittance", "Admittance", "Admittance", False),
     Label("serr", "Series R", "Series R", False),
diff --git a/NanoVNASaver/Marker/Widget.py b/NanoVNASaver/Marker/Widget.py
index ae88139..10cddc8 100644
--- a/NanoVNASaver/Marker/Widget.py
+++ b/NanoVNASaver/Marker/Widget.py
@@ -35,6 +35,7 @@ from NanoVNASaver.Formatting import (
     format_q_factor,
     format_resistance,
     format_vswr,
+    format_wavelength,
     parse_frequency,
 )
 from NanoVNASaver.Inputs import MarkerFrequencyInputWidget as FrequencyInput
@@ -317,6 +318,7 @@ class Marker(QtCore.QObject, Value):
             x_p_str = ind_p_str
 
         self.label['actualfreq'].setText(format_frequency_space(s11.freq))
+        self.label['lambda'].setText(format_wavelength(s11.wavelength))
         self.label['admittance'].setText(format_complex_imp(imp_p))
         self.label['impedance'].setText(format_complex_imp(imp))
         self.label['parc'].setText(cap_p_str)
diff --git a/NanoVNASaver/RFTools.py b/NanoVNASaver/RFTools.py
index 160f85e..2eb1151 100644
--- a/NanoVNASaver/RFTools.py
+++ b/NanoVNASaver/RFTools.py
@@ -55,6 +55,10 @@ class Datapoint(NamedTuple):
             return 1
         return (1 + mag) / (1 - mag)
 
+    @property
+    def wavelength(self) -> float:
+        return 299792458 / self.freq
+
     def impedance(self, ref_impedance: float = 50) -> complex:
         return gamma_to_impedance(self.z, ref_impedance)