The Nine Titans in Attack on Titan do not have official canon weights, so any numbers you see are fan estimates rather than confirmed values. A common fan discussion lists weights by Titan form and treats them as rough guesses, not source material.

Common fan estimates

Titan Estimated weight
Founding Titan No reliable canon weight; often treated as unknown
Attack Titan No reliable canon weight; often treated as unknown
Colossus Titan Often estimated around 430 tons in fan calculations
Armored Titan No reliable canon weight; fan estimates vary
Beast Titan No reliable canon weight; fan estimates vary
Cart Titan No reliable canon weight; fan estimates vary
Female Titan No reliable canon weight; fan estimates vary
Jaw Titan No reliable canon weight; fan estimates vary
War Hammer Titan No reliable canon weight; fan estimates vary

What the sources suggest

One fan thread gives a rough size-based estimate that puts a 3-meter Titan at about 100 kilograms and scales the Colossus Titan to about 800,000 kilograms, while another discussion estimates the Colossus Titan around 430 tons. The problem is that these are independent fan calculations, so the numbers conflict and should be treated as speculative.

Practical answer

If you want a simple answer, the safest version is this: the Nine Titans do not have officially confirmed weights, and only fan estimates exist.