I am booked United MEL to SFO as part of a circle pacific fare I am also booked SFO to KIX Both these sectors are long Upgrades for both with mileage plus are 30000 points But

I am booked United MEL to SFO as part of a circle pacific fare

I am also booked SFO to KIX

Both these sectors are long

Upgrades for both with mileage plus are 30000 points

But the service charge for the SFO to KIX is 600, whereas MEL-SFO is only 350

It's mileage plus

How com its more for the shorter flight?

When you say 'service charge', are you talking about a co-payment for taxes and surcharges, or a fixed booking fee?

It says 'upgrade service fee' $350 on the receipt

I am fine with the price, I just can't understand why a 2 sector trip costs $250 less than a 1 sector that is a few hours shorter

Taxes and charges vary per sector and airport landing charges vary from airline to airline in different country's  this applies to separate bookings .sometimes I find it's cheaper to book multiple sectors as an  award flight as the charges and tax can vary .

This is the same airline United for all sectors

It does list separate sectors for upgrade - they are not bundled

30000+$350 - Mel to SFO (via SYDNEY)

30000 +$650 - SFO to KIX (Direct)

Correction $600 not $650