Spots going fastCosta Diadema vs Costa Firenze
Side-by-side cruise ship comparison · Updated February 2026
Costa Diadema offers more personal space with a space ratio of 35.6 GT per passenger versus 31.9. Built in 2021, Costa Firenze is 7 years newer — an advantage for travellers seeking modern amenities and design. Costa Firenze accommodates 508 more guests (4,232 vs 3,724), making it the larger resort-at-sea — Costa Diadema trades capacity for a more intimate atmosphere.
Score: 2 – 5
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Category
Costa Diadema
Costa Firenze
Size
132,500 GT
135,225 GT
Passengers
3,724
4,232
Year Built
2014
2021
Crew Ratio
1:3.0
1:3.0
Space Ratio
35.6
31.9
Decks
—
—
Length
306m
323m
From Price
$1,997/pp
—
Comparison Verdict
Costa Diadema offers more personal space with a space ratio of 35.6 GT per passenger versus 31.9. Built in 2021, Costa Firenze is 7 years newer — an advantage for travellers seeking modern amenities and design. Costa Firenze accommodates 508 more guests (4,232 vs 3,724), making it the larger resort-at-sea — Costa Diadema trades capacity for a more intimate atmosphere.
| Category | Winner |
|---|---|
| Size | Costa Firenze |
| Capacity | Costa Firenze |
| Modernity | Costa Firenze |
| Service | Costa Diadema |
| Spaciousness | Costa Diadema |
| Decks | Tie |
| Length | Costa Firenze |
| Fleet Power | Costa Firenze |
Bottom line: Costa Firenze leads 5–2 across our categories — strongest in Size. Choose Costa Firenze for overall superiority; pick Costa Diadema if Service matter more to you.
Which Ship Is Right for You?
Choose Costa Diadema if...
- Better service ratio (3.0:1 crew ratio)
- More space per guest (35.6 GT/pax)
Choose Costa Firenze if...
- You want the newer ship (built 2021, 7yr newer)
- Size matters to you (135,225 GT)
- More onboard variety (4,232 guests)
You've compared the ships. Now see what they cost.
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Sailing Prices
| Costa Diadema | Costa Firenze | |
|---|---|---|
| Cheapest | $1,997 pp | — |
| Departing | Jul 31 | — |
| Duration | 7 nights | — |
| View Deal |
Prices from Cruisebound. We may earn a commission at no extra cost to you.
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Frequently Asked Questions
How is the comparison score calculated?
We compute scores across 8 categories using real spec data — gross tonnage, passenger capacity, crew capacity, year built, length, deck count, space ratio, and fleet power. Each category awards one point to the winning ship.
What is the space ratio and why does it matter?
Space ratio is gross tonnage divided by passenger capacity. A higher number means more space per guest. Luxury lines typically score above 40; mass-market ships often fall in the 30-40 range.
What does the passenger-to-crew ratio mean?
Passengers per crew member. Lower is better — more staff per guest means better service. Luxury lines aim below 2:1; large mainstream ships may be 3-4:1.
Are the prices shown accurate?
Prices are sourced from Cruisebound and reflect real-time availability. They may change based on cabin type, date, and demand. Click through to see the latest fares.
Can I compare more than two ships?
Yes — up to four ships. Use the search tool on the compare hub page to add additional ships.
How current is the ship data?
Specifications come from our database of 380+ vessels, revalidated every 5 minutes via ISR. The "Updated" timestamp shows when records were last modified.
