The thing you want is an oximeter. You can purchase medically calibrated ones through Amazon. I use the Nonin Go 2. Less expensive ones are available at Walmart and Walgreen.

I also picked one up at the pharmacy. Inexpensive and a valuable tool to have

Hi Musk, like Barbara said they are fairly easy to find and purchase. You can go anywhere from the cheaper battery ones to the more expensive wire ones. While having one that is accurate a important my thought on it is just have one. If it's the cheaper one and if by a few it at least give you an idea. I use mine all the time. You should be between 92 / 94. The 80s not to good and y need to see a doctor. 70s or lower 80s like 82 / 84 you probably should go to the ER. Have a good day. Take care. Breathe easy

Mine cost about $12 from the drugstore. I took it to the doctor's office to have it checked. It seems to be accurate and I use it a lot.

You can buy a plus oximeter at a drug store there not that expensive and very important to have