For F-35A/C:

18,000 lb total weapon load equates to:

5,700 lb (int) +

12,300 lb (ext) = 18,000 lb

The tallied weight allowance for each pylon comes to.

Max internal = 5,700 lb

Max external = 16,600 lb ... ... (4,300 lb more than the available 12,300 lb for external stores in a 18,000 lb total allowable payload)

Total = 22,300 lbA maximium external load configuration would be:

2 x 5,000 lb weapon (includes 2 x 550 lb pylons)

2 x 2,500 lb weapon (includes 2 x 550 lb pylons)

2 x 300 lb (includes 2 x 113 lb pylons)

1 x 1,000 "multi-mission pod" (as centerline station is reported rated for 1,000 lb)

Which brings it up to about

16,600 lb of total max external weight that could be added to the jet.

I don't see a configuration where 18,000 lb external is even possible, unless the pylon stations were capable of carrying more weight than claimed. For instance, if a higher external weight was made possible via a reduced certification +/- G range. i.e. the official 18,000 lb of total payload would represent the allowable payload, without reducing +/-G numbers below required G ranges. Thus a "Beast mode" loading would only be viable with a reduced agility envelope in battle, plus non-standard weapons, and this may degrade structural life also. I'm betting we never see maximum loadings like that.

But even if you had full-fuel plus an actual 22,300 lb weapon load the takeoff-weight still only comes to 69,797 lb, or 203 lb less than MTOW

Now, if you had full-fuel plus the full 18,000 lb weapons load (theoretically possible, but unlikely) the actual takeoff-weight only comes up to 65,497 lb, or 4,503 lb less than certified MTOW.

But if you have full-fuel plus the maximum long-range standoff strike configuration possible, you get this: 2 x JSM @ 950 lb each = 1,900 lb

2 x AIM-120D @ 355 lb each = 710 lb

Full internal load = 2,610 lb2 x AIM-9X @ 187 lb each = 374 lb

4 x JASSM-ER @ 2,250 lb each = 9,000 lb

Add pylon weight: 4 x Heavy weapon pylon @ 550 lb each + 2 x AAM rail pylon @ 113 lb each = 2,426 lb

Full external loading is therefore = 11,800 lbSo the maximum long-range strike takeoff weight is

11,800 lb external plus

2,610 lb internal =

14,410 lb So, full-fuel plus the 14,410 lb, comes to

61,907 lb for a maximum strike-loading at takeoff, or

8,093 lb less than MTOW.

In this relatively light configuration power to weight looks like this:

Dry thrust:28K lb Thrust @100% fuel = 0.452

28K lb Thrust @50% fuel = 0.532

Wet thrust:43K lb Thrust @100% fuel = 0.695

43K lb Thrust @50% fuel = 0.817

And the

achievable cruise altitude such a light takeoff weight and the

resulting climb and cruise fuel-burn efficiency benefit will provide is a lot higher than what all prior strikefighters could achieve with their maximum long-range strike loads.

EDIT1: I slipped up with the middle pylon's allowable weight limit, resulting numbers now adjusted.

EDIT2: All numbers

updated using 'Spurts' suggested pylon weight additions, given immediately below.