Correspondence between the L60 and L91 model levels showing the values of full level pressure, p_L60 and p_L91, respectively, for a surface pressure of PS[hPa]= 1013.250.

A description of how model levels should be interpreted is available in the IFS Documentation Part III - Chapter 2, Section 2.2.1.

N (L60)p_L60 [hPa]N (L91)p_L91 [hPa]
10.140.1015
20.292160.2768
30.510470.4285
40.796480.6396
51.150690.9244
61.5753101.2985
72.0768111.7781
82.6664122.38
93.3623133.1209
104.193144.0176
115.2013155.086
126.4443166.3417
137.9844177.7988
149.8925189.4706
1512.25651911.3688
1615.18562115.8844
1718.81462218.5179
1823.31082424.5653
1928.88162527.986
2035.78362735.6281
2144.3352944.331
2254.62363154.0701
2366.62333364.7978
2480.39683682.5725
2595.97813895.6172
26113.421240109.8913
27132.757743134.3981
28153.995245153.3538
29177.117647174.7166
30202.085949198.7556
31228.838751225.7656
32257.355853256.069
33287.638455290.0175
34319.630757327.9948
35353.225658348.6233
36388.2760393.4375
37424.570761417.7338
38461.899763470.1659
3950064497.9584
40538.591365526.462
41577.375467584.4855
42616.041768613.4989
43654.273169642.2899
44691.751571698.7032
45728.163172726.0656
46763.204573752.6718
47796.587875803.1575
48828.046976826.8141
49857.341977849.2512
50884.266179890.134
51908.650680908.4403
52930.370281925.2226
53949.349483954.0914
54965.567284966.1707
55979.063385976.6735
56989.943587993.3027
57998.385488999.8373
581004.644891005.122
591009.056901009.146
601012.049911012.049