diff --git a/functions/pressure_conversion.py b/functions/pressure_conversion.py
new file mode 100644
index 0000000..96744c4
--- /dev/null
+++ b/functions/pressure_conversion.py
@@ -0,0 +1,77 @@
+# convert to Pa
+def bar_to_pa(p):
+    return p*1e5
+
+def mWS_to_pa(p):
+    return p*9.80665*1e3
+
+def torr_to_pa(p):
+    return p*133.322
+
+def atm_to_pa(p):
+    return p*101.325*1e3
+
+def psi_to_pa(p):
+    return p*6894.8
+
+# convert from Pa
+def pa_to_bar(p):
+    return p*1e-5
+
+def pa_to_mWS(p):
+    return p*1/(9.80665*1e3)
+
+def pa_to_torr(p):
+    return p/133.322
+
+def pa_to_atm(p):
+    return p*1/(101.325*1e3)
+
+ # converstion function
+
+def pa_to_psi(p):
+    return p/6894.8
+
+def pressure_conversion(pressure, input_unit = 'bar', target_unit = 'Pa'):
+    p = pressure
+    if input_unit.lower()   == 'bar':
+        p_pa = bar_to_pa(p)
+    elif input_unit.lower() == 'mws':
+        p_pa = mWS_to_pa(p)
+    elif input_unit.lower() == 'torr':
+        p_pa = torr_to_pa(p)
+    elif input_unit.lower() == 'atm':
+        p_pa = atm_to_pa(p)
+    elif input_unit.lower() == 'psi':
+        p_pa = psi_to_pa(p)
+    elif input_unit.lower() == 'pa':
+        p_pa = p
+    else:
+        raise Exception('Given input unit not recognised. \n Known units are: Pa, bar, mWs, Torr, atm, psi')
+    
+    if target_unit.lower()      == 'bar':
+        return pa_to_bar(p_pa), target_unit
+    elif target_unit.lower()    == 'mws':
+        return pa_to_mWS(p_pa), target_unit
+    elif target_unit.lower()    == 'torr':
+        return pa_to_torr(p_pa), target_unit
+    elif target_unit.lower()    == 'atm':
+        return pa_to_atm(p_pa), target_unit
+    elif target_unit.lower()    =='psi':
+        return pa_to_psi(p_pa), target_unit
+    elif target_unit.lower()    == 'pa':
+        return p_pa, target_unit
+    else:
+        raise Exception('Given target unit not recognised. \n Known units are: Pa, bar, mWs, Torr, atm, psi')
+
+# testing_pressure_conversion
+if __name__ == '__main__':
+    p = 1
+
+    unit_dict = ['Pa','Bar','Torr','Atm','MWS','psi']
+
+    for input_unit in unit_dict:
+        for target_unit in unit_dict:
+            converted_p = pressure_conversion(p,input_unit,target_unit)
+            print(input_unit,target_unit)
+            print(converted_p)
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