Short answer: it depends on the airline and the fare class. Below are the typical allowances for the main carriers on the Colombo (CMB) — Chennai (MAA) route — but always check the allowance printed on your ticket/booking before travel.

• SriLankan Airlines (frequent operator on CMB–MAA)

  • Checked baggage (Economy): typically a weight-based allowance (about 30 kg per passenger on most non‑Americas routings); Business/First larger (≈40 kg).
  • Cabin baggage: 1 piece (Economy) up to 7 kg (Business 2 pieces up to 7 kg each). (ffpmobile.srilankan.com)

• IndiGo (low‑cost carrier)

  • Cabin baggage: 1 handbag up to 7 kg (plus a small personal item).
  • Checked baggage on international sectors: often not included in the lowest/no‑frills fares (you buy a checked allowance or pre‑pay excess); check your fare conditions — IndiGo’s site documents hand‑baggage rules and paid checked baggage options. (goindigo.in)

• Air India

  • Typical economy checked allowance shown on their site is in the region of 30 kg (business/premium classes higher). Cabin allowance generally 7–10 kg depending on class. Confirm on your booking. (airindia.com)

• SpiceJet (if operating the sector via interline)

  • Cabin: 7 kg. International checked allowances vary by route/fare and may be sold as piece or weight concept — confirm for your ticket. (corporate.spicejet.com)

Tip: baggage rules vary by fare family, frequent‑flyer status, interline/partner tickets and can change — the single most reliable source is the airline’s baggage page or the allowance shown in your e‑ticket/Manage My Booking. If you tell me which airline and fare class (or paste the allowance shown on your ticket), I can interpret it for you.