Calculate when to replace your battery based on capacity fade
Original design capacity when new
Current measured capacity
Number of charge cycles used
Average cycles per day of use
Higher temps accelerate fade
Typically 80% for Li-ion batteries
Enter your battery data and click calculate
Most manufacturers recommend replacing lithium-ion batteries when capacity drops below 80% of the original design capacity. At this threshold, devices typically show noticeable runtime drops and unexpected shutdowns. For smartphones, laptops, and EVs, the 80% mark is the industry standard for end-of-life.
A typical lithium-ion battery lasts 2 to 5 years or 500 to 1000 full charge cycles before capacity fades to 80%. Lifespan varies by usage patterns, operating temperature, depth of discharge, and charging habits. High temperatures and deep discharges accelerate capacity fade.
Battery capacity fade can be calculated by dividing the difference between initial and current capacity by the number of cycles, giving you fade per cycle. Then project when future capacity reaches 80% using: Remaining Cycles = (Current Capacity - 0.80 × Initial Capacity) / Fade Rate Per Cycle. Temperature and discharge depth adjust this rate.