How do you weigh yourself when normal household scales don't work?

I will admit that I am obese… My weight well exceeds the 250kg limit on the scales at my local doctors.

Before you ask, I am going to the gym every day, and eating a decent diet… but I’d like to be able to get a starting weight, and check my progress.

But as I said, household scales, AND those at the local doctors clinic, just give me an error.

Thanks.