Estimate total cruise trip cost.
The advertised cruise fare is typically only 55 to 70 percent of what a cruise actually costs, and the remainder is structurally predictable rather than optional. Daily gratuities are charged automatically per person per night and are not usually removable. Shore excursions are where the largest discretionary spend goes, often several hundred per person on a week-long itinerary. Onboard extras — drinks, wifi, speciality dining — accrue per day and compound with trip length. Reporting the fare as a share of the total is the useful output: if it lands near 55 percent, the fare you compared between operators was telling you little about the real cost.
Gratuities
Gratuity total = daily rate x nights x passengers
Grand total
Total = fare x passengers + gratuities + (excursions + daily extras x nights) x passengers
On most major lines it is applied automatically to your onboard account and removing it requires a specific request at guest services, which some lines decline outright. Premium and luxury lines increasingly include it in the fare. Treat it as a fixed cost when comparing operators unless you have confirmed otherwise.
Excursions are the biggest lever — independent tours or self-guided port days often cost a fraction of the ship's offering. Beyond that, assess a drinks package honestly against your actual consumption, and be aware that wifi and speciality dining are priced to be bought impulsively once you are aboard.