How pip value is calculated for EUR/GBP
EUR/GBP is a cross: neither currency is the US dollar. One pip on a standard lot is worth 0.0001 × 100,000 = 10 GBP, converted to US dollars by multiplying by the GBP/USD rate. At GBP/USD 1.2700 that is $12.70. The pip value moves with GBP/USD, not with the EUR/GBP price.
Worked example
Holding 1 standard lot of EUR/GBP: Assumes GBP/USD at 1.2700, an example rate.
0.0001 × 100,000 × 1.2700 = $12.70
One pip is worth $12.70. A 30-pip move is worth $381.00 on one lot, $38.10 on a mini lot and $3.81 on a micro lot.
These are the calculator's default inputs above, so its result matches.