The table below shows the mapping between Undertale OST track names and in-game music filenames. Where an OST track corresponds with multiple in-game music filenames, brace expansion syntax is used to represent the filenames.

All OST tracks are present in the game files, except 72 (Song That Might Play When You Fight Sans).

Track number Track title Filename
1 Once Upon a Time mus_story
2 Start Menu mus_menu{0..6}
3 Your Best Friend mus_flowey
4 Fallen Down mus_toriel
5 Ruins mus_ruins
6 Uwa!! So Temperate♫ mus_options_fall
7 Anticipation mus_prebattle1
8 Unnecessary Tension mus_tension
9 Enemy Approaching mus_battle1
10 Ghost Fight mus_ghostbattle
11 Determination mus_gameover
12 Home mus_house1
13 Home (Music Box) mus_house2
14 Heartache mus_boss1
15 sans. mus_muscle
16 Nyeh Heh Heh! mus_papyrus
17 Snowy mus_snowy
18 Uwa!! So Holiday♫ mus_options_winter
19 Dogbass mus_dogmeander
20 Mysterious Place mus_mystery
21 Dogsong mus_dogsong
22 Snowdin Town mus_town
23 Shop mus_shop
24 Bonetrousle mus_papyrusboss
25 Dating Start! mus_date
26 Dating Tense! mus_date_tense
27 Dating Fight! mus_date_fight
28 Premonition mus_mysteriousroom2
29 Danger Mystery mus_undynescary
30 Undyne mus_undynetheme
31 Waterfall mus_waterfall
32 Run! mus_undynefast
33 Quiet Water mus_waterquiet
34 Memory mus_musicbox
35 Bird That Carries You Over A Disproportionately Small Gap mus_birdsong
36 Dummy! mus_dummybattle
37 Pathetic House mus_napstahouse
38 Spooktune mus_spoopy
39 Spookwave mus_spoopy_wave
40 Ghouliday mus_spoopy_holiday
41 Chill mus_napstachords
42 Thundersnail mus_race
43 Temmie Village mus_temvillage
44 Tem Shop mus_temshop
45 NGAHHH!! mus_undynetruetheme
46 Spear of Justice mus_undyneboss
47 Ooo mus_oogloop
48 Alphys mus_lab
49 It's Showtime! mus_{mtgameshow,tv}
50 Metal Crusher mus_mettatonbattle
51 Another Medium mus_anothermedium
52 Uwa!! So HEATS!!♫ mus_options_summer
53 Stronger Monsters mus_battle2
54 Hotel mus_hotel
55 Can You Really Call This A Hotel, I Didn't Receive A Mint On My Pillow Or Anything mus_hotel_battle
56 Confession mus_confession
57 Live Report mus_news
58 Death Report mus_news_battle
59 Spider Dance mus_spider
60 Wrong Enemy !? mus_wrongworld
61 Oh! One True Love mus_mettmusical{1..4}
62 Oh! Dungeon mus_operatile
63 It's Raining Somewhere Else mus_sansdate
64 CORE Approach mus_coretransition
65 CORE mus_core
66 Last Episode! mus_mettafly
67 Oh My… mus_mettaton_pretransform
68 Death by Glamour mus_mettaton_ex
69 For The Fans mus_mettsad
70 Long Elevator mus_elevator_last
71 Undertale mus_endarea_part{a,b}
73 The Choice mus_chokedup
74 Small Shock mus_smallshock
75 Barrier mus_barrier
76 Bergentrückung mus_bergentruckung
77 ASGORE mus_vsasgore
78 You Idiot mus_yourbestfriend_3
79 Your Best Nightmare mus_{repeat_{1,2},f_{intro,part{1,2},alarm,6s_{1,6}}}
80 Finale mus_f_finale_{1_l,2,3}
81 An Ending mus_{z_ending,endingexcerpt{1,2}}
82 She's Playing Piano mus_undynepiano
83 Here We Are mus_hereweare
84 Amalgam mus_amalgam
85 Fallen Down (Reprise) mus_fallendown2
86 Don't Give Up mus_dontgiveup
87 Hopes and Dreams mus_xpart
88 Burn in Despair! mus_a2
89 SAVE the World mus_xpart_2
90 His Theme mus_xpart_{a,b}
91 Final Power mus_xpart_back
92 Reunited mus_reunited
93 Menu (Full) mus_menu6
94 Respite mus_leave
95 Bring It In, Guys! mus_cast_{1..7}
96 Last Goodbye mus_express_myself
97 But the Earth Refused to Die mus_x_undyne_pre
98 Battle Against a True Hero mus_x_undyne
99 Power of "NEO" mus_mettaton_neo
100 MEGALOVANIA mus_zz_megalovania
101 Good Night mus_piano