It depends a lot on when the war happened and under what circumstances. A conflict in 1980 over Afghanistan or something would be very different from one in 1989.
Around 1980 the Warsaw Pact's strength was estimated to be around:
16 DDR divisions
24 Polish divisions
12 Czech divisions
10 Hungarian divisions
20 Romanian divisions
8 Bulgarian divisions
Totaling some 800, 000 men.
The Soviets had 46 divisions in Germany alone, and around 2-3 million in Eastern Europe and the western USSR.
Against that NATO was outnumbered in both divisions and men. The largest armies were the US and FRG at around 300, 000- 400, 000 each. Belgium and the Netherlands had around six divisions in West Germany, and the figures for Denmark, Luxembourg, and other minor powers are likely fairly insignificant, unlikely to total much more than ten divisions together. NATO was also outnumbered in the areas of tanks and artillery, but had an advantage in air power.
But it's not that simple. The two forces had different military strategies and political, economic, social, and military realities. NATO had an advantage in population as well as a more diversified economy, but in a short conflict it likely wouldn't have the ability to use these to their fullest. Plus, NATO would have to ship the bulk of their forces and equipment overseas from America, Canada, and the UK whereas the Soviets simply needed to hop on a train to the front.
Generally speaking the Soviets overwhelmingly favored a sort of "rush b" doctrine against the West. Their armies were technologically inferior and had less training than their NATO counterparts, so the Warsaw Pact attempted to make up for this through surprise and speed. A significant DDR, Polish, and GSFG unit was to advance into West Germany across the North German Plain and the Fulda Gap. Meanwhile, a large Hungarian, Czech, and Soviet force would invade Austria into northern Italy in an attempt to reach either the French border (assuming France continues to refuse integrated NATO command) or Lyon should France cooperate fully with NATO.
In all likelihood the Warsaw Pact would have decent success in the NGP, especially since the NATO units stationed there were overwhelmingly Dutch, Belgian, and some FRG units and not the strongest outfits in the NATO arsenal. Warsaw Pact forces in the Fulda Gap would face a much harder time, especially as they'd be going up against the bulk of the American, British, and Canadian forces stationed in West Germany. Austria wouldn't be able to provide much of any resistance to the Warsaw Pact, and I doubt NATO would invade the country to try and cut off Warsaw Pact troops north of Italy.
Even with this highly mobile war of movement (the fastest and most mobile in history) estimated casualties were always very high. NATO expected to lose some 500, 000 men in the first couple of weeks or so of combat, and Warsaw Pact casualties could likely run near 1, 000, 000. The amazing amounts of ammunition expected to be expended by massed Soviet artillery and tanks was expected to deplete Warsaw Pact stocks within a matter of weeks, and the same goes for NATO. What we're thus likely to see is a short period of intense border bombardment followed by incredibly heated border armor and mechanized infantry clashes, followed by a bloody Warsaw Pact breakthrough along multiple sections of the front. From here the war would assume a highly mobile character, with Warsaw Pact forces likely having devastated the advanced NATO units so badly that the bulk of the NATO forces would have been forced to retreat in mass in order to re-group for a defensive posture further west in FRG, likely near the Weser River. Warsaw Pact casualties would mount as their ammo runs out, and somewhere west of the Weser the front stalls as American forces are brought in. By now both sides have exhausted their best units, and the match becomes one of two tired boxers slugging each other hoping the other collapses first. In all likelihood NATO air supremacy would begin to carry the day and be brought to bear against the overextended Warsaw Pact lines, starting a renewed round of rapid movement eastward into the DDR itself, with the shattered Warsaw Pact units likely being unable to mount an effective defense in time. Within a week or so from here Berlin is likely re-captured by NATO forces as NATO troops fan out across the DDR and to the river Oder. At this point both sides would have run out of much of their pre-stocked ammunition and other supplies as well as almost all of their veteran units, and a ceasefire would likely be signed. Germany is reunified into a neutral country, Italy, Denmark, Norway, and possibly Czechia become neutral countries as well, and maybe, depending on how things go, Bulgaria and Romania leave the Warsaw Pact to pursue a path similar to Yugoslavia.