Estimate how long caffeine stays in your system with our Caffeine Half-Life Calculator. Track energy levels, sleep disruption, and dose timing using science-based metabolism models tailored to your sensitivity and lifestyle.

Estimate training intensity and load with our RPE Calculator. Use the Rate of Perceived Exertion to plan personalized strength training, adjust effort in real time, and make smarter progress with every workout. Ideal for lifters and coaches alike.