The ThermoFlask, sold primarily through Costco as a two-pack at a very low price point, enjoys strong community support as a high-value alternative to premium bottles like Hydro Flask and Yeti. Reviewers consistently praise its insulation performance as comparable to much more expensive competitors, with many owners reporting years of reliable daily use. Minor complaints about lid durability and the 40oz size not fitting cup holders are the main caveats.
ThermoFlask delivers legitimate long-term durability and excellent insulation at a fraction of the price of premium competitors, but lid fragility from drops and the 40oz cup holder issue prevent a full unconditional endorsement.
Community members overwhelmingly highlight ThermoFlask's exceptional value for the price, with insulation performance that matches or rivals premium brands. Long-term durability and easy-to-clean, interchangeable lids are frequently praised.
The most common complaints are that the 40oz bottle doesn't fit standard cup holders and that lids can break when dropped. A minor leaking issue with the straw lid and some plastic content were also noted by a small number of users.
One owner who compared five brands including Yeti, Stanley, Contigo, Hydro Flask, and ThermoFlask concluded that the ThermoFlask was simply the best because it was the cheapest — and performed the same as the rest.
A parent of four kids noted they've bought the Costco two-pack repeatedly over the years, not because the bottles fail but because they keep getting left behind — a backhanded testament to how replaceable and affordable they are.
One user reported their ThermoFlask from Costco kept hot coffee hot for over eight hours during a full day of snowboarding in the mountains, and also kept cold drinks cold — with two lid types included in the box.
A longtime owner mentioned they've had their ThermoFlask for ten years with only cosmetic wear, and the only lid replacement they made was by choice — wanting a straw lid — not because anything broke.