How pip value is calculated for GBP/USD
GBP/USD is quoted in US dollars, so its pip value is already in USD: 0.0001 × 100,000 = $10.00 per standard lot, whatever the price. For a USD account a pip on GBP/USD is always worth $10.00 per lot, $1.00 per mini lot and $0.10 per micro lot.
Worked example
Holding 1 standard lot of GBP/USD:
0.0001 × 100,000 = $10.00
One pip is worth $10.00. A 30-pip move is worth $300.00 on one lot, $30.00 on a mini lot and $3.00 on a micro lot.
These are the calculator's default inputs above, so its result matches.