Protein is the macro most people under-eat, and the one that does the most work for body composition. How much you need depends less on a single rule and more on what you are asking your body to do.
TL;DR — Enter your weight and goal in the protein intake calculator to see a daily target range.
Why protein matters
Protein builds and repairs muscle, keeps you fuller than carbs or fat, and is the macro that protects lean mass when you are losing weight. If a diet is costing you muscle, too little protein is usually part of the reason.
How much you need
The baseline for general health is roughly 0.8 g per kg of body weight — enough to avoid deficiency, but not optimized for training. People who exercise, are dieting, or want to build muscle do better in the range of about 1.6–2.2 g per kg. Endurance and strength athletes sit toward the top of that band.
Spread it across the day
Your body uses protein best when it arrives in regular doses rather than one big hit. Aim to include a protein source at each meal — that makes a higher daily total far easier to reach and supports muscle repair throughout the day. Find your range in the protein intake calculator and build your meals around it.