A pace calculator expresses time per unit distance, such as minutes per kilometer or mile. Speed is distance per unit time, so converting between them requires consistent units. For 10 km in 50 minutes, average pace is 5:00 per km; that does not mean every kilometer was run at the same pace.
Enter total elapsed time and distance, then check whether pauses are included. For splits, compare their sum with the total and note GPS measurement error. A target pace is a planning number, not medical or training advice for an individual. Adjust effort for terrain, conditions, and health rather than forcing a calculator's target.
Akousa