Short answer — FitsAir is generally cheaper than SriLankan Airlines on the Colombo–regional routes that FitsAir serves, and it’s in the same low-cost price band as AirAsia (sometimes slightly higher or lower depending on the dates/fare sale).

Key evidence and a quick comparison (sources at the end):

• FitsAir launch/intro fares: FitsAir advertised promotional round‑trip fares to Kuala Lumpur around LKR 60,000–65,300 (examples: “starting from LKR 60,000” and an LKR 65,300 launch fare). (FitsAir.com)
• Market listings: online OTAs show one‑way FitsAir tickets to KUL starting around USD 123 and average roundtrip examples around USD 260 on some dates. That matches the airline’s low‑cost positioning. (Traveloka.com)
• SriLankan Airlines (full‑service carrier) list prices for Colombo→Kuala Lumpur are noticeably higher in many searches — the SriLankan site often shows roundtrip economy “from” fares near LKR ~89,000 (and OTA/aggregate searches commonly show SriLankan fares higher than the FitsAir promo). (srilankan.com)
• AirAsia (another low‑cost carrier) commonly appears as the cheapest on Colombo–Kuala Lumpur in flight searches (examples: Google Flights showing AirAsia roundtrips from ~$178 on some dates). That places AirAsia in the same low‑cost bracket as FitsAir; which one is cheaper depends on the specific travel dates, how far ahead you book, and which promotions are running. (Google.com)

A concrete price example (to make the comparison easier):

• FitsAir promo ~LKR 65,300 roundtrip → about USD 215–216 using October 2025 exchange rates (~LKR 302–303 per USD). (LKR → USD rates vary; I used the October 2025 market rate to illustrate.) (Newswire.lk)
• SriLankan example shown on its site: ~LKR 89,000 → about USD 294 (same exchange context). (srilankan.com)
• AirAsia sample low fares in searches: often from about USD 114–$180 one‑way/roundtrip deals around USD 178 (so comparable or sometimes cheaper than FitsAir depending on the sale). (Google.com)

What this means for you:

• If you want the lowest base fare and are happy with a low‑cost product (carry‑on/limited frills), FitsAir and AirAsia are the closer options. On many dates AirAsia may be the cheapest, but FitsAir’s launch promos put it very competitive with AirAsia.
• SriLankan Airlines (full‑service) generally prices higher because its fares include a different set of services (meals, baggage rules differ by fare bucket), so expect to pay a premium vs. FitsAir/other LCCs unless there’s a special sale.
• Exact cheapest option on your travel dates will vary — fares change quickly by date, time, availability and baggage/seat choices.

If you want, I can:

• Check specific dates and routes you care about and pull current prices across FitsAir, SriLankan and AirAsia so you can see a head‑to‑head comparison (I’ll show exact fares, baggage allowances and total price).