PSU Calculator
Build a source-labeled wattage estimate without mixing component load, planning headroom, and a conditional manufacturer system minimum.
Planning estimate, not a compatibility certificate. Choose an exact bundled profile or enter your own watts. Nominal capacity alone cannot verify connectors, rails, transients, quality, efficiency, case fit, or electrical safety.
Suggested nominal class
- Component planning load CPU + GPU + other load
- After entered headroom Exact arithmetic before class rounding
- Class before system floor First offered nominal class at or above target
- Manufacturer system floor Kept separate; never added to component watts
Field-by-field provenance
Source and assumption receipt
Automatic copy was blocked. Select the current receipt below and copy it manually; CSV remains available.
Private calculation: selections, watts, source note and results stay in this tab and are not sent to ToolNeko or analytics. Copy receipt writes the current receipt to your system clipboard; Download CSV saves a file through your browser. This page does not put build data in URLs, storage, cookies, requests, diagnostics, or analytics.
What this PSU calculator actually computes
Component planning load equals CPU planning watts + GPU planning watts + other system watts. The headroom target equals that sum × (100 + your headroom percentage) ÷ 100. If an applicable manufacturer system minimum is available, the required planning target is the larger value—not the sum of both. The result is the first nominal class in the bounded list from 450 W through 2,000 W that meets the controlling target.
RTX 4070 reference example: why the result is 650 W
Choose Ryzen 7 7800X3D, enter 120 W as your own CPU planning assumption, keep the RTX 4070 Founders Edition/reference 200 W TGP, enter 60 W for the rest of the system, and use 30% headroom. The component load is 380 W and the headroom target is 494 W, which rounds up to a 500 W nominal class before any manufacturer floor.
NVIDIA separately lists 650 W Required System Power for its RTX 4070 reference specifications. Its footnote says that minimum used a Ryzen 9 5900X test PC and requirements can vary by configuration. The calculator therefore shows 500 W and 650 W in separate rows, then lets the conditional 650 W floor control the final class. It never calculates 380 + 650.
Why CPU TDP is context, not a hidden peak estimate
AMD's current Ryzen 7 7800X3D page calls 120 W “Default TDP.” That value is visible beside the result, but the calculator leaves CPU planning power blank until you enter the assumption you want to use. Intel's Core i9-14900K page publishes separate 125 W Processor Base Power and 253 W Maximum Turbo Power fields; the 253 W field is used only as an editable starting point.
The receipt keeps every manufacturer field name, source URL, checked date, and dataset version. Custom components remain user assumptions. Unsupported hardware is never replaced with a nearby model.
Wattage is one compatibility check, not the whole build
A sufficient nominal wattage does not establish connector fit, cable rating, 12 V rail behavior, transient response, PSU quality, efficiency, ATX form factor, card dimensions, case clearance, or electrical safety. NVIDIA's reference connector guidance also does not automatically apply to every board-partner card. Compare the receipt with the exact graphics card, CPU, motherboard, case, and PSU manuals before buying or installing hardware.
Private, local, versioned calculation
The source snapshot contains two CPU records and one precisely identified reference GPU record. It is not a copied competitor catalog and it makes no real-time hardware claim. Official records are reviewed at least quarterly and sooner when a cited page changes; any record marked “source needs recheck” is disabled until it is verified in a new dataset version. Inputs and results stay in the browser; the page makes no task API request, stores no build by default, and creates copy/CSV output locally. Open a manufacturer link only when you want to inspect the source yourself.
Frequently asked questions
How many watts does my gaming PC need?
Add the CPU planning power, GPU planning power, and an explicit allowance for the rest of the system. Apply only the headroom percentage you choose, then compare that target with any manufacturer minimum that applies to your exact card edition. This page reports the first listed nominal PSU class at or above the controlling value.
Can I use a 550 W PSU for an RTX 4070?
This calculator does not give an unconditional yes. NVIDIA lists 650 W Required System Power for its RTX 4070 Founders Edition/reference specifications, based on a Ryzen 9 5900X test PC, and says requirements can vary. Board-partner cards and other systems need their own manuals and specifications.
Is CPU TDP the same as peak power?
No. Manufacturer field names have different meanings. AMD lists the Ryzen 7 7800X3D at 120 W Default TDP, while Intel separately lists 125 W Processor Base Power and 253 W Maximum Turbo Power for the i9-14900K. The calculator keeps those labels and asks for an editable CPU planning value.
Why is the manufacturer minimum separate from component watts?
A system minimum already describes a complete reference system under stated assumptions. Adding it to the CPU, GPU, and other watts would double-count the build. The calculator instead takes the larger of the component target and the applicable manufacturer floor.
Does a wattage result prove the PSU is compatible?
No. Check the exact graphics card and PSU manuals for connector count and rating, rail capacity, ATX version, transients, quality, efficiency, dimensions, case clearance, and installation requirements. A nominal wattage class is only a planning estimate.
Does the PSU calculator work offline?
After this page and its small bundled source snapshot load, calculation, receipt, clipboard copy, and CSV creation run in your browser. Source links need a network connection only when you choose to open them.