Apply Tsiolkovsky’s rocket equation to wet mass, dry mass and specific impulse. Check ideal delta-v capability, propellant needed for a manoeuvre, reserve allowance and remaining mass.
Ideal single-stage vacuum equation Δv = Isp·g₀·ln(m₀/mf), with g₀ = 9.80665 m/s². It excludes gravity and drag losses, finite burns, boil-off, unusable propellant, staging, engine-out rules and trajectory constraints.