The conventional answer is 15%. The FIRE answer is as much as possible. Here's how to find the right number for your actual goals.
Saving and investing 15–20% of gross salary from your mid-20s, combined with state pension, gets most people to a comfortable retirement at 65. This is the baseline. Below 15% and you're relying heavily on state pension, which is increasingly uncertain.
Pushing toward 30% of salary invested from your late 20s means financial independence a decade before conventional retirement. Still liveable — you don't have to sacrifice dramatically.
This is where lifestyle trade-offs become real. In low-tax environments (UAE, Singapore), 50% savings rates are achievable on professional salaries without extreme frugality. In high-tax countries, you may need a high income to make this work after tax.
Automate your investment the day you're paid. The percentage comes before lifestyle, not after. Most people who fail to hit savings targets do so because they spend first and invest "what's left."