Investment risk tolerance is largely a personal decision that depends on your goals and other facets of your financial situation. A tolerable risk level for a young investor with few assets may not be right for someone nearing retirement.
For context, Wealthfront can build portfolios personalized to your risk tolerance, which is scored between 0.5 and 10.0. You can use the example portfolio on Wealthfront’s website to get an idea of what your portfolio would look like with different risk scores.