I took my husband on a cruise for $4 less than cruising solo, including airfare and gratuities

It all started with a work trip, a promotional offer and a bit of mathematical detective work that would make any budget traveler proud.

But let me back up.

Cruise pricing can be confusing. Fares constantly fluctuate based on demand; the same itinerary on the same ship on different dates can have fare differences of hundreds of dollars. Certain cabin locations cost more than others, even for the same room type. Check cruise fares today, and they’re almost guaranteed to be different tomorrow.

To find the best cruise deal for your desired sailing, you might need to abandon conventional logic and embrace a touch of creative chaos.

I only meant to find the best cruise fare for an upcoming trip, but I stumbled on a pricing quirk that helped me save a few bucks and, more importantly, stretch my cruise dollars further. Here’s how I made a startling discovery about cruise fares and how this knowledge can help you save, too.

Related: I booked a sailing through American Airlines Cruises — was it worth it?

A surprising cruise fare discovery

I mainly cruise with my husband or my family, but this time, I was booking a solo trip to review Royal Caribbean‘s Voyager of the Seas for TPG. As such, I began my booking search based on a single passenger.

If you’ve never booked a solo cruise, you should know that most cruise lines charge a single supplement fee, which can be a significant hurdle for solo cruisers. Cruise lines apply this charge to recoup the revenue they could earn from a second passenger, who would likely spend money on things like spa treatments, drinks and shore excursions.

As I searched for the best cruise fares, I discovered that, in many cases, a solo cruiser would pay the same total cruise fare (if not a bit higher) than what two people would pay for the same cabin.

However, I discovered something interesting during the booking process. Royal Caribbean was offering a 60% discount for the second guest as part of the line’s wave season promotions (which typically run from January to March). During wave season, cruise lines often roll out some of their most competitive sales.

Of course, it’s a good idea to take cruise promotions with a grain of salt, as they might not always be the best deal. However, the 60% discount on a second passenger offer prompted me to compare the costs of cruising alone versus sailing with my husband.

As I progressed through the booking process, I realized something remarkable. Booking for two wasn’t just the same price as going solo — it was cheaper than going solo.

Related: Ways to get a deal on a cruise

The guarantee cabin advantage

How is it possible for two people to cruise for less than one person alone? Let me tell you.

During my search for a two-passenger cabin, I unlocked a new savings opportunity. When I reached the step of picking a cabin, I was given the option to choose a “guarantee” cabin for a discounted rate that was not offered to me when I searched single-passenger fares. Intriguingly, this option wasn’t presented at all when booking for a single passenger for any sailing. (I confirmed this through multiple test bookings.)

What exactly is a guarantee cabin? You choose the cabin category (balcony, ocean-view, etc.), but the cruise line selects the specific location. While you’re guaranteed at least the cabin type you chose, if not a higher category, you relinquish control over its placement on the ship. Cabin assignments are typically revealed closer to departure.

The appeal of a guarantee cabin lies in the potential savings and the possibility of an upgrade if your chosen cabin category sells out. The guarantee cabin fares on my cruise, based on two people sharing a cabin, were $140 less per person than the cheapest available room where you could select your location.

The trade-off? Your cabin might be in a less desirable location, near noisy elevators or above a nightclub, or your window or balcony might have an obstructed view.

How much I saved adding a second passenger

When I compared the costs of cruising solo versus sharing a guarantee cabin, the numbers were eye-opening. A solo cruise would have cost me $2,081.51 (including taxes and fees), while adding my husband brought the total fare down to just $1,736.03 (including taxes and fees).

Of course, traveling as a couple leads to other expenses. I also had to factor in the cost of an additional flight to the cruise port and prepaid gratuities for one more person (per day). Needless to say, my gob was thoroughly smacked after I did the math — because the trip was still cheaper to take as a couple than as a solo traveler!

Here’s how the numbers stacked up.

Costs for a solo cruise

• Fare for balcony cabin: $2,081.51
• Gratuities: $92.50 ($18.50 per day)
• Flight: $249 round-trip

Total cost: $2,423.01

Costs for a two-person cruise

• Fare for balcony (guarantee) cabin: $1,736.03
• Gratuities: $185 ($18.50 per day, per person)
• Flight: $498 total ($249 round-trip per ticket)

Total cost: $2,419.03

The result? I would save $3.98 by adding my husband. As a bonus, since the cruise was in February, I was off the hook for buying him a Valentine’s Day gift.

Bottom line

The math was clear — my husband was going to accompany me in order to save money. (Plus, I got extra photography help, to boot.) Our guarantee cabin risk paid off, too. We received our cabin number about two weeks before our departure date. Our room was in a quiet area of the ship, and while our balcony overlooked a lifeboat, the view was perfectly acceptable.

Searching for the biggest savings on a cruise fare is often an exercise in patience, but it can be worth the effort. This cruise booking experience opened my eyes to the potential of guarantee fares and how thinking creatively about cabin categories and fare classes can lead to unexpected savings.

In my case, it meant that I’d save money booking two people on a no-frills fare versus traveling solo in a room location I chose. You might discover that sharing a suite with your family is cheaper than booking two separate rooms — or vice versa — or that declining “free” perks allows you to spend less on your vacation.

My takeaway is this: Cruise pricing does not always make sense at first. Instead of struggling with this notion, use it to your advantage. Be creative with the cabin combinations you compare as you price out your next sailing, and you might be pleased to find a cruise deal hiding in plain sight.

Planning a cruise? Start with these stories:

• The 5 most desirable cabin locations on any cruise ship
• A beginners guide to picking a cruise line
• The 8 worst cabin locations on any cruise ship
• The ultimate guide to what to pack for a cruise
• A quick guide to the most popular cruise lines
• 21 tips and tricks that will make your cruise go smoothly
• Top ways cruisers waste money
• The ultimate guide to choosing a cruise ship cabin