I'm sorry, it's actually called national insurance. am I making an incorrect assumption? I'm just going off this tax calculator: https://www.moneysavingexpert.com/tax-calculator/

Yep, incorrect. National Insurance is not an NHS tax.

sorry to be obtuse, did I just call it the wrong name or is it completely different? I'm american and I just assumed that NHS is the government org that handles healthcare and a mandatory contribution is pretty similar to a tax.

See my comment above. Not all of National Insurance goes to the NHS, and not all NHS funds come from National Insurance. There exists no special tax whose revenue is earmarked for the NHS. Thus, there is no easy way to see how much of your pay you are contributing to the NHS. Similarly, someone in the US can’t easily see how much of their pay goes to the US military or to the National Science Foundation.

edit: On an individual level, a lot will depend on your income, and how expensive your US health insurance is. Here is an informative post:

https://www.quora.com/If-you-make-100-000-in-UK-what-percent...

That works out to about $560/month for someone with a salary of $100,000. If you take into account employer contributions, that's still less than a lot of Americans are paying. If you're on a lower income, you're likely to be paying significantly less in the UK for much better coverage.

And I almost forgot - copays! The amount you're paying in taxes in the UK really is paying for virtually the full cost of your treatment when you're sick.

understood, ty for the explanation.