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Power Adapter Wattage Estimator — Check Charger Output

Estimate your charger wattage based on battery drain and system load.

Estimate your laptop power adapter wattage based on platform and typical charger specs.

Rough estimate only
Battery status: Checking…

Select your laptop brand for a more specific estimate:

Common adapter wattages by brand

Brand Common Wattages (by model)
Apple 30 W (MacBook Air), 67 W (MacBook Pro 13"), 96 W (MacBook Pro 14"), 140 W (MacBook Pro 16")
Dell 45 W (Latitude), 65 W (XPS 13), 90 W (XPS 15), 130 W (XPS 17), 240 W (Precision workstations)
Lenovo 45 W (ThinkPad X-series), 65 W (ThinkPad T-series), 90 W (ThinkPad P-series), 135 W (Legion gaming)
HP 45 W (EliteBook), 65 W (Spectre), 90 W (Envy), 150 W (Omen gaming)
ASUS 45 W (ZenBook), 65 W (Vivobook), 100 W (ROG Zephyrus), 200 W (ROG Strix)
Acer 45 W (Swift), 65 W (Aspire), 90 W (Predator gaming)
Microsoft 65 W (Surface Pro), 90 W (Surface Laptop), 127 W (Surface Book)
Samsung 25 W (Galaxy Book), 45 W (Galaxy Book Pro), 65 W (Galaxy Book Ultra)

How it works

How the power adapter estimator works

This tool combines two inputs to provide a rough estimate: your platform (detected from the browser) and the laptop brand you select. If your browser supports the Battery API (Chrome on HTTPS), it also checks whether your laptop is currently charging. The estimate is then looked up from a table of common adapter wattages for that brand and platform.

This is not a measurement. It is a guess based on typical configurations. The only way to know your exact adapter wattage is to read the output rating printed on the physical charger.

How to find the real wattage

Turn your power adapter over and look for the regulatory label. Find the line labelled OUTPUT or DC Output. It will show a voltage (V) and current (A) rating. Multiply them: Volts × Amps = Watts. For example, "20V ⎓ 3.25A" means 20 × 3.25 = 65W. On USB-C chargers, the wattage is often printed directly as "65W" or "100W".

Common USB-C power delivery wattages

Most modern laptops use USB-C Power Delivery (PD) at these standard wattages: 18W (phones/tablets), 30W (ultraportables), 45W (thin laptops), 65W (standard laptops), 90-100W (performance laptops), 130-140W (Pro workstations), 240W (gaming/workstation via EPR). Using a lower-wattage charger than your laptop expects will result in slower charging or battery drain under load.

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Frequently Asked Questions

How accurate is this wattage estimate? expand_more
It is a very rough estimate based on your platform and selected laptop model. Actual wattage depends on the exact charger model, power delivery negotiation, and system load. <strong>Always read the physical label on your charger</strong> for the real wattage.
Where do I find the actual wattage on my charger? expand_more
Look for the fine print on the power adapter brick. You will see "OUTPUT" followed by a voltage and current rating — for example "20V ⎓ 3.25A" = 65W. On USB-C chargers, the wattage may also be listed as "65W" directly. Never guess from the charger size alone.
Why does my browser not show charging status? expand_more
The Battery API has been deprecated in many browsers (Firefox, Safari). Chrome still supports it but only on secure contexts (HTTPS). If your browser cannot report battery status, this tool falls back to a purely model-based guess.
Can I use this to test a third-party charger? expand_more
This tool can give you a rough idea of what wattage your laptop likely expects, but it cannot detect the actual power draw of a third-party charger. A low-wattage charger may still charge the battery, just slower — especially under load.
Why do different brands use different wattages? expand_more
Each laptop brand designs its charging system around its power delivery (PD) protocol. Dell uses proprietary EPR (Extended Power Range) for high-wattage charging, while Apple, Lenovo, and HP use standard USB-C PD at different negotiated voltages. Always match the exact wattage your laptop supports.