Experience points are one of the most widespread concepts in roleplaying games. Many RPGs use point-buy experience systems or provide variable scale rates of advancement. D&D 4th Edition’s experience system functions by characters accruing points and gaining levels at specific point totals. The system, as presented in the PHB and other resources, uses a single scale of experience point values required to level up, and the stated assumption is that characters will gain a level around every ten encounters, give or take.
This assumption can be used to calculate roughly how much playtime it will take to go from level 1 to level 30. In practice, the experience required to go up a level can be gained in fewer than ten encounters, thanks to a combination of quest rewards, experienced gained from skill challenges and other noncombat encounters, and higher-level combat encounters. One can generally assume around seven combat encounters will provide sufficient experience to gain a level.
According to the assumptions of RPGA organized play events, a four hour session should be sufficient to make it through about three encounters and a bit of roleplaying. In my own experience as an RPGA DM, this assumption is not too far off the mark. Thus, for every two to three sessions of play (at four hours per session), one can expect to gain a level.
If the above assumptions hold true, then gaining 29 levels should take roughly sixty to ninety sessions, likely leaning towards the higher end. A campaign running from level 1 to level 30, then, can be expected to take over a year of play, even if a group plays once a week without fail. In practice, it is likely to be somewhere between a year and a half to two years of play, with one session of four hours a week.
Once you understand the expected duration of a 1-30 campaign, based on the assumed rate of advancement, it becomes much easier to play with it. Some DMs don’t bother tracking experience totals numerically, advancing their players in level whenever it feels appropriate to do so. This works well, but can lead to some levels being “longer” than others if it is not tracked—going by the numbers at least ensures a consistent rate of advancement. Numbers can be adjusted easily, as well.
For example, if you wanted to slow advancement slightly, you might shift the total experience required to level up to reflect twelve encounters rather than ten—three to four sessions, rather than 2-3. This would mean that second level is reached at 1200 experience, third at 2500, fourth at 4300, and so on. You could also speed things up, aiming for 8 encounters, ensuring a level increase every second session—second level would then be 800 experience, third at 1800, fourth at 3000, etcetera.
Adjusting experience requirements isn’t difficult, especially once one understands the play time the numbers represent. There are two things one must bear in mind, however, before deciding to go forward with such an alteration. First, the treasure parcel system will need to be adjusted to reflect any changes. If you reduce the number of encounters between leveling up, you should either hand out treasure faster or use the inherent bonuses system presented in the DMG2—simply because the defenses and attacks of monsters assume that at certain levels, a certain minimum enhancement bonus will have been applied to players. The other consideration is that you must let your players know before you begin about any adjustments you have made.
Experience and advancement are an important part of any roleplaying game, and by understanding the assumptions the game designers have made in creating these systems it becomes much easier to adapt them to suit your group’s particular requirements, be they for a speedier game or a lengthier campaign duration.