Experience

Killing monsters and fulfilling certain tasks will grant players experience (also known as xp, exp) which they can accumulate to increase their levels in professions. Players will start a profession with zero experience, and are able to level their professions to level 500.

Experience table

The following table shows the relationship between the profession level, the experience required for that level, and the experience difference from the previous level:

Level	Experience	XP needed for level up
Novice
0	0	500
1	500	515
2	1,015	530
3	1,545	545
4	2,090	561
5	2,651	578
6	3,229	1,189
7	4,418	1,224
8	5,642	1,260
9	6,902	1,297
10	8,199	1,335
11	9,534	1,374
12	10,908	2,828
13	13,736	2,911
14	16,647	2,997
15	19,644	3,084
16	22,728	3,175
17	25,903	3,268
18	29,171	3,364
19	32,535	3,462
Apprentice
20	35,997	17,818
21	53,815	18,164
22	71,979	18,517
23	90,496	18,877
24	109,373	19,244
25	128,617	19,619
26	148,236	20,000
27	168,236	20,389
28	188,625	20,785
29	209,410	21,189
30	230,599	21,601
31	252,200	22,011
32	274,221	22,449
33	296,670	22,886
34	319,556
Journeyman
50	752,539
75	1,762,204
Adept
100	3,396,108
125	6,040,195
150	10,319,013
175	17,243,259
Expert
200	28,448,494
225	89,611,386
250	160,276,100
275	241,918,762
300	336,244,832
325	445,224,715
350	571,134,915
375	716,605,603
400	884,675,555
425	1,078,855,621
450	1,303,202,085
475	1,562,401,381
Ultimate
500	1,861,867,939

Required experience amount breakpoints

Based on the above table, we can notice a few breakpoints in the experience formula:

For the sake of being rigorous, the following data has been observed based on an incomplete chart, not datamined.

Novice:

Levels 0-6 : every level requires around 2,95% more experience than the previous one;

Levels 7-12: every level still requires 2,95% more experience, but the required experience is also doubled;

Levels 13-20: again, every level requires 2,95% more experience, but it is once again doubled.

For example, going from level 13 to level 14 requires slightly more than 4x the experience required from level 4 to level 5.

Apprentice to expert:

Levels 21-200: the required experience, per level, has been quintupled (explaining why you suddenly feel like you hit a wall once you are at skill level 20), and every new level from 21 to 200 requires 1,94% more experience than the previous one.

Expert to ultimate:

Levels 201-500: the required experience per level is once again quadrupled, then every new level requires around 0,60% more experience than the previous one.

To say it differently: at level 20, you've got 4,8% of the experience to level 50, 1% of the experience to level 100, 0,13% of the experience to level 200 and 0,002% of the experience to level 500.

At level 100, you've got 12% of the experience to level 200, and 0,2% of the experience to level 500.

At level 200, you've got 1,5% of the experience to level 500.

At level 350, you've got 30,7% of the experience to level 500.

Conclusions:

While I haven't checked the increase in experience gained per action yet, I assume it follows a fairly similar formula regarding the percentage increases, but completely ignores the multipliers at specific breakpoints. It'd mean that you have indirect penalties if you do underleveled content, but that each level takes a similar amount of actions if you do "on-level" content (barring the breakpoint multipliers).

Levels 0-20 are certainly made easier for the sake of allowing players to explore new professions quickly.

Levels 21-200 look like the intended regular levels, requiring some dedication.

Finally, levels 201+ require an absurd amount of experience and are likely here to make sure players end up specializing in something if they want to pursue leaderboards and the ultimate cape.

Additional data needed:

Providing exp gained per action isn't quadrupled either for levels 201+, it would be interesting to know whether converting knowledge into experience ends up being the fastest way to level past this point, considering knowledge conversion seems to be granting around 20-25% of a full level. I don't have a high level skill personally so additional data would be very helpful.