Estimate when to replace a tablet.
Tablets fail on cycles and on support, not on speed. Lithium-ion cells are rated for roughly eight hundred full cycles before capacity drops to about eighty percent, and converting your charging habit into cycles used gives a battery runway. Comparing that with the operating system support window shows which constraint binds first — for lightly used tablets it is almost always software support.
Cycles consumed
Cycles used = charge cycles per week x months owned x 30 / 7
Remaining life
Battery months left = (800 - cycles used) / (cycles per week x 4.345); useful months = min(OS support left, battery months left)
A full one hundred percent of capacity discharged, however it accumulates — two fifty percent discharges make one cycle. Topping up frequently does not consume cycles faster.
As an offline reader, media player or kitchen display, yes. For browsing, banking or email it becomes a liability once security patches stop.