How long does a 65W USB-C charger take to fully charge a laptop?

It depends on the battery's capacity. In this calculator's CC/CV model at 65W effective power, a 60Wh laptop battery reaches a practical full charge in roughly 110 minutes, while a 100Wh battery takes roughly 180 minutes. The last 20% of charge takes disproportionately longer than the first 20%, since charging tapers during the CV phase.

Do OnePlus and Xiaomi phones charge at full speed with a generic USB-PD charger?

Usually not. OnePlus, Xiaomi, Oppo and Vivo mostly use proprietary fast-charging protocols such as SUPERVOOC and HyperCharge, which only reach their full advertised wattage with the OEM charger and cable. On a generic USB-PD charger they typically fall back to a lower speed, often in the 18-45W range.

Does a 65W-rated charger always deliver exactly 65W to a device?

No. The device negotiates its own charging power over USB-PD based on what it supports, which is often lower than the charger's maximum rating. An iPhone, for example, typically negotiates around 20-30W even from a 65W charger.

USB-PD Charge Time Calculator

Interactive

Charge Time Calculator

Choose a laptop battery capacity, or pick a phone by brand and model — the charge power auto-fills from its USB-PD spec and you can still fine-tune it.

Charging Setup

Battery capacity 60 Wh

Target State of Charge 100%

SoC above 80% enters the CV taper phase — charging slows down.

Effective charge power 65 W

What the battery actually receives (laptop off/sleeping). Default matches a 65W PD negotiation at 100% charge-path efficiency — the AC-DC adapter's own wall-side efficiency (see Assumptions) does not affect this figure.

Result

Time to target SoC

109.7 min

≈ 1h 50m

Time to 80% (t1)

44.3 min

≈ 44m

Time to ~100% (99.5%)

109.7 min

≈ 1h 50m

CC phase — constant power CV phase — exponential taper

Energy delivered (Wh) — left axis State of charge (%) — right axis

Reference Data

Charge Time by Battery Capacity

Time in minutes from 0% SoC, at 65W effective charge power — for the seven reference laptop battery capacities in the source model.

Model

Assumptions & Method

Pulled directly from the source workbook's Assumptions sheet.

Charger rated output

65 W

Charge-path efficiency

100%

Battery receives the full 65W, per design/test data

CC → CV threshold

80%

CV time-constant factor

0.4 × t1

AC-DC wall-side efficiency

90%

Reference only — adapter's mains-side draw ≈ 65 / 0.90 ≈ 72.2W

CC phase (0% → 80% SoC): battery charges at constant effective power, so time is linear in SoC and capacity. t = (SoC / 100 × Capacity_Wh) / P_eff
CV / taper phase (80% → 100%): current tapers down (standard Li-ion CC-CV behaviour), modeled as an exponential approach to full: SoC(t) = 100% − (100% − 80%) × exp(−(t − t1) / τ) where τ = 0.4 × t1, scaled so the CV-phase duration scales sensibly with battery capacity.
A pure exponential taper never mathematically reaches exactly 100%, mirroring how real chargers terminate on a low current cutoff (~C/20) rather than an exact SoC. The "100%" figures above represent that practical 99.5% cutoff — standard practice for reporting Li-ion charge curves.
All figures are engineering estimates for planning purposes, not a specific vendor's measured charge curve. Tune power, threshold and τ to match a real charger/battery datasheet if available.
Wall-side power (reference only): the 65W above is what the laptop actually receives over USB-PD — the negotiated contract power — not the adapter's input from the mains. Per design/test data the battery receives the full 65W, so charge-path efficiency is 100% and it does not factor into the times above. The adapter's own AC-DC conversion efficiency (90%) only affects what it draws from the wall: P_wall = 65W / 0.90 ≈ 72.2W. That number is shown for completeness but plays no part in the charge-time calculation.
Mobile phones: the same generic CC/CV model (80% threshold, τ = 0.4×t1) is applied to phone batteries for consistency. Real phone fast-charging often tapers earlier — commonly 50–70% SoC rather than 80% — especially on the highest-wattage protocols, so treat phone results as a reasonable approximation, not a measured curve. Battery capacities are converted from the manufacturer's mAh rating at an assumed 3.85V nominal cell voltage unless the exact Wh is published.
Proprietary fast charging (OnePlus, Xiaomi, Oppo, Vivo): these brands mostly use proprietary protocols (SUPERVOOC, HyperCharge, Warp Charge, etc.) that only reach their full advertised wattage with the OEM charger and cable. On a generic/standard USB-PD charger they typically fall back to a lower speed — often in the 18–45W range. This calculator uses the standard USB-PD figure for its calculation and shows the OEM proprietary figure separately for reference only.

Phone battery/charging specs verified as of August 2026, from publicly reported figures — new models may not yet be included.

Charge Time Calculator

Charging Setup

Result 🔗 Copy link

Charge Time by Battery Capacity

Assumptions & Method

Result