Square the foot, square the factor
A foot is 0.3048 m, so a square foot is 0.3048² = 0.09290304 m², exactly, and a square metre is 10.7639 square feet. The factor is squared, which is why the numbers move so much more than for lengths: a 1,000 ft² apartment is 92.9 m², not 305. Real-estate listings in the US, Canada and India use square feet; Europe, Australia and most of the world use square metres.
square metres = square feet × 0.09290304 | square feet = square metres ÷ 0.09290304
Rough conversion in your head
Divide square feet by 10 and take off 7%: 2,000 ft² → 200 − 14 = 186 m² (true 185.8). Multiply square metres by 10 and add 8%: 75 m² → 750 + 60 = 810 ft² (true 807). For a fast sanity check, a 10 × 10 ft room is 100 ft² or 9.3 m²; a 3 × 3 m room is 9 m² or 97 ft².