Imperial Star Destroyer vs UFP Galaxy class in five minutes (canon materials only)

Maximum anti-capital ship range:
ISD: 4 000 - 6 000 km
GCS: 225 000 km

Maximum energy weapons firepower:
ISD: 0.33-3.2 megatons per shot heavy and 5.8-22.8 kilotons per shot medium turbolasers
GCS: 2.39 gigatons per second

Maximum torpedo firepower:
ISD: none
GCS: 500 to 600 Mt per torpedo
Maximum sublight speed:
ISD: 0.25 c
GCS: 0.25 c minimum (0.9 c seen in TOS, 0.8 c seen in VOY)

Maximum FTL speed:
ISD: 80 000 to 1 563 792 c
GCS: 21 000 to 20 000 000 c (latter is only possible inside well-explored area)

Maximum shield strength:
ISD: 126-925 megatons
GCS: 25-75 Gt[1]; up to some teratons

Energy production (non-combat):
ISD: 500 to 7500 TW (5 x 10e14 - 7.5 x 10e15 W)
GCS: 5 840 000 000 000 TW (5.84 x 10e24 W).

[1] As far as I can recall, on several occasions they were concerned that "full torpedo spread" at point-blank range could destroy ship; full spread might be 5 to 10 torpedoes - GCS has shown to be able to launch at least 5 torpedoes simultaneously. That was before invention of shaped-charge torpedoes, so I took that 1/3rd of blast would hit ship in such case.

In 2367, if a torpedo was fired by a Galaxy-class starship with shields, at a target in close range, the torpedo explosion could cripple the firing ship. When shield strength was increased 300 percent, the ship remained undamaged when a full spread of maximum yield torpedoes was detonated at close range. (TNG: "The Nth Degree")

NOTE: I mostly used materials from st-v-sw.net, by Mr. Anderson, but I will keep updating this page as I make my own calculations.

Canon and non-canon sources for Star Trek vs Star Wars discussion

Canon sources:
On-screen evidence (ST,SW)

Non-canon sources:
Incredible Cross Sections (SW)
Memory Beta (ST)
Memory Gamma (ST)
Technical Manuals (ST)
Expanded Universe (SW, ST) -includes books, video games etc.

Semi-canon sources:
Comments from production staff, firms etc.
Various estimates derived from movies

Mixed canonity sources:
Wookiepedia (SW, ~1-5% canon)
Memory Alpha (ST) -supposed to be canon, but non-canon technical manuals are permitted source so it is of mixed canonity. Still more canon than Wookiepedia.