I am not saying you should do this. In fact, don't do this.
But after recurrent early miscarriages, if you need something just to get the days to pass, this is how you can try and measure HCG levels at home: you need a number of small pots, a syringe (eg from child medicine bottle) and loads of the cheapo ebay pregnancy tests. Take a morning urine sample, in 1st pot. Luke warm water 0.5mls in the other pots. Then put 0.5 mls of urine in 2nd pot: it is now diluted by half. If you are using a 25mIU stick and it is positive, your urine level must be at least 50mIU. Then put 0.5mls from pot 2 into pot 3. If this is positive your level must be 100mIU... etc etc. You have to apply a certain degree of scientific rigour to this, eg rinsing out syringe each time, being acurate etc.
These do not equal blood levels, so I can't tell you a normal range, but the levels should logically be doubling every 48hours like blood levels, until about 8 weeks.
This will not tell you if you are going to ultimately miscarry. But, personally, (and this may be just random), I have not miscarried in the few days after my levels had doubled.
I'm just putting out there. Feel free to think I have totally lost the plot. I think those who have had miscarriages will understand.