A1 should be ≈1m for it to be elegant.
Paper weight is measure in grammes per square metre. 80gsm is typical for ordinary paper.
A0 = 2⁰ m² = 1 m² → 80g
A1 = 2¯¹ m² = 0.5 m² → 40g
...
A4 = 2¯⁴ m² = 0.0625 m² → 5g
Though maybe we could have A3.1 Gen 2x2 for thick blue paper with glossy texture folded 4 times but 2 of those folds weren't down the middle.
It depends on your point of view on what you are comparing.
A0 area = 0.5^0 = 1 m^2
A1 area = 0.5^1 = 0.5 m^2
A2 area = 0.5^2 = 0.25 m^2
A3 area = 0.5^3 = 0.125 m^2
A1 area = 1 m^2
A2 area = 0.5 = 0.5 ^ (2-1) m^2
A3 area = 0.25 = 0.5 ^ (3-1) m^2
A0 = 1/(2^0) m^2
A1 = 1/(2^1) m^2
A2 = 1/(2^2) m^2
And so on
(EDIT for formatting and also to observe a sibling post to mine is making the same point)