USB-C charger & cable wattage checker.
Your charger can say 140W while the usable charging path is limited to 60W. WattageFit checks charger, shared power, port, cable, device reference and charging protocol — then shows the weakest rated link. The Upgrade Impact Lab then tests whether changing only one link would actually raise that ceiling before you buy anything.
Check the whole chain
Start with a source-backed device preset or enter your own values. WattageFit finds the lowest rated power ceiling, explains it, then models whether a cable, source or sharing change would actually improve the rated path. It does not measure live device draw.
Choose your device
Describe your charger
Cable & usage
Target-capable
Power chain
Would changing one part actually help?
Run the checker to compare single-change scenarios.
Keeps charger, port and shared load unchanged.
Models enough source budget for the target while keeping the cable unchanged.
Sets the entered other-device load to 0W and changes nothing else.
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Counterfactual model only: each card changes one input while holding the others constant. It does not predict negotiated USB-PD power, charging time, product compatibility or real device draw.
Wattage is only one number
USB-C charging is negotiated end-to-end. A large charger cannot overcome a low-power port, cable, protocol or device limit.
Shared charger budget
A 100W multi-port charger may not give one port 100W while another device is drawing power.
Port vs. cable limits
The brick, selected port and cable can all have different ceilings. WattageFit compares each one.
Device & protocol
Your device decides what it accepts. Some phones also need PPS for their advertised fastest charging.
Not sure what your device needs?
Browse manufacturer-sourced presets with published minimums clearly separated from values the manufacturer does not specify.
Short answers to common charging questions
What wattage USB-C charger do I need?
How to size a charger without overspending — and why a larger rating is usually safe.
CablesCan a 60W cable slow a 100W charger?
Yes. The cable can be the lowest power ceiling in the whole chain.
Multi-portWhy 100W chargers do not always deliver 100W
Understand total power, per-port limits and dynamic power sharing.
Interactive toolPlan one charger for several devices
Pick your laptop, phone and tablet, then calculate the total wattage, strongest port, protocol and cable requirements to look for.
ProtocolsUSB PD, PPS and EPR in plain English
The protocol labels that actually matter when matching modern chargers and devices.
Compare45W, 65W, 100W or 140W?
Compare common USB-C charger sizes and what each one changes.
Quick answers
Can a 140W charger damage a 65W laptop?
With standards-compliant USB-C Power Delivery equipment, the device negotiates what it accepts. A higher charger rating is a ceiling, not power forced into the device.
Does a 60W cable limit a 100W charger?
It can. If the device wants more than 60W, a cable with a 60W power rating becomes the limiting link.
Why does a multi-port charger slow down when I plug in a phone?
Many multi-port chargers redistribute a shared total power budget. The printed total rating is not necessarily available on every port at the same time.
Is this result exact?
No. Browsers cannot see live USB-PD negotiation from this tool. WattageFit compares published charger requirements, rated limits and your inputs. The “available path capacity” result is a compatibility ceiling, not a wattmeter reading; battery temperature, charge level, firmware and charger allocation can change real-world behavior.
Planning a standby generator location?
Try wall, opening and property-line clearances in an interactive side-yard precheck before you commit to a location.
Standby Generator Placement Planner
Drag the generator and nearest opening, enter your local setback, and compare the candidate spot with manufacturer guidance. Planning precheck only — not permit approval.