How much caffeine is enough to energize? A personalized guide to finding your optimal dose
                                
                                
                                •
                                
                                
                        
                                    
                                    5 min read                                
                            
                                According to the U.S. Food and Drug Administration (FDA), up to 400 milligrams of caffeine a day is considered safe for most healthy adults. However, figuring out how much caffeine is enough to energize depends on a multitude of factors, including your metabolism, genetics, and personal tolerance.