On the NG if you go to the N1 Limit page and enter the OAT at 1L you will get the 26K N1 at line 1R, assuming your airline doesn't have the T/O Bump option.
If the packs are on, switching them off will increase the figure by 0.8%.
The 24K and 22K derate figures are available by selecting 2L and 3L.
If you enter an assumed temp at 1L the figures at 1R will change to reflect that value,again approx 0.8% difference packs on / off.