Battery wear range sheet

Type the maximum capacity from iPhone Settings and, if you have it, the cycle count, then download a sheet with the wear-per-month range and the months left before 80%, always as a range and never as a score.

Current month

Every result is a range with a ±25% band around the observed average. No single-number prediction, no health score.

You provided: Purchase month, Maximum capacity %, Cycle countEstimated: Age (months), Wear % per month, Months to 80%, Cycles per month

Device

Purchase month

Maximum capacity %

Cycle count

Age (months)Estimated

Wear % per monthEstimated

0.38–0.63

Months to 80%Estimated

12–22

Cycles per monthEstimated

17.2

Device

Purchase month

Maximum capacity %

Cycle count

Age (months)Estimated

Wear % per monthEstimated

0.00–0.00

Months to 80%Estimated

No measurable wear yet

Cycles per monthEstimated

—

Device

Purchase month

Maximum capacity %

Cycle count

Age (months)Estimated

Wear % per monthEstimated

0.24–0.40

Months to 80%Estimated

Already at or below 80%

Cycles per monthEstimated

—

Up to 10 devices.Cycle count is optional; iOS shows it under Battery Health on newer models.

Device

Maximum capacity %You provided

Months to 80%Estimated

Already at or below 80%

Your entries stay in this tab. No upload, account, tracking of entries or saved data. Reloading clears your edits.

Worked example

Three devices checked in 2026-09: one two-year-old iPhone at 88% with 412 cycles, one new phone still at 100%, and one older phone already at 79%.

Device	Purchase month	Maximum capacity %	Cycle count	Age (months)	Wear % per month (low)	Wear % per month (high)	Months to 80% (low)	Months to 80% (high)	Source
Device 1	2024-09	88	412	24	0.38	0.63	12	22	You provided: Purchase month, Maximum capacity %, Cycle count; Estimated: Age (months), Wear % per month, Months to 80%
Device 2	2026-08	100		1	0.00	0.00	No measurable wear yet	No measurable wear yet	You provided: Purchase month, Maximum capacity %; Estimated: Age (months), Wear % per month, Months to 80%
Device 3	2021-03	79		66	0.24	0.40	Already at or below 80%	Already at or below 80%	You provided: Purchase month, Maximum capacity %; Estimated: Age (months), Wear % per month, Months to 80%
Current month	2026-09

Download example CSV

Formula and limits

Wear per month = (100 − capacity) ÷ age in months, shown as a ±25% band. Months to 80% = (capacity − 80) ÷ wear, low bound from the high wear rate and high bound from the low rate. Cycles per month = cycle count ÷ age.

Device 1: (100 − 88) ÷ 24 = 0.50 %/Age (months) → ±25% → 0.38–0.63; (88 − 80) ÷ Wear % per month → 12–22
Device 2: (100 − 100) ÷ 1 = 0.00 %/Age (months) → ±25% → 0.00–0.00; (100 − 80) ÷ Wear % per month → No measurable wear yet
Device 3: (100 − 79) ÷ 66 = 0.32 %/Age (months) → ±25% → 0.24–0.40; (79 − 80) ÷ Wear % per month → Already at or below 80%

Capacity from 60 to 100 as a whole percent, cycle count from 0 to 3000, purchase month between 2007 and 2099 and one to 240 months old, up to 10 devices. Months are YYYY-MM. Inputs stay in this tab; nothing is measured or read from your phone.

Maximum capacity %: 60 ≤ x ≤ 100
Cycle count: 0 ≤ x ≤ 3000
Age (months): 1 ≤ m ≤ 240
Device: 1 ≤ n ≤ 10

Optional apps

No app is required for this free worksheet. Check each App Store listing for current features and prices.

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