PSU Calculator: Power Supply Wattage Calculator

Short answer: most gaming PCs need a 550W to 850W power supply, and the graphics card decides which end you land on. An RTX 5060-class build is comfortable on 550W, an RTX 5070 on 650W, an RTX 5070 Ti on 750W, an RTX 5080 on 850W, and an RTX 5090 on 1000W — NVIDIA’s own published minimums. On the AMD side our estimates are 650W for an RX 9070 or RX 9060 XT and 750W for an RX 9070 XT. Pick your exact parts in the power supply calculator below for a number built from your build rather than a category.

Worked examples

These are this calculator’s own outputs, computed with the same formula the tool runs in your browser — so you can see a real answer without touching a single input.

Mainstream 1440p gaming build — Ryzen 7 7800X3D + RTX 5060 Ti (OC model), 2x DDR5, one Gen3 NVMe, 3 case fans, one AIO, ATX board. (This is the tool’s own default state, so it is the number a visitor sees on page load.)

• Inputs: CPU = Ryzen 7 7800X3D (120W); GPU = RTX 5060 Ti OC (200W peak); DDR5 sticks = 2; Gen5 NVMe = 0; Gen4 NVMe = 0; Gen3 NVMe = 1; SATA SSDs = 0; HDDs = 0; case fans = 3; AIO = 1; USB/misc = 10W; motherboard = ATX (45W)
• Result: Peak draw 409W | Min recommended 550W | Sweet spot 850W. Headline: “Minimum recommended PSU: 550W — your build peaks at 409W. For a 40–50% load target, the optional efficiency-focused size is 850W (48% utilization), which sits in the 80 Plus efficiency sweet spot (40–50%).”

High-end 4K gaming build — Ryzen 7 9800X3D + RTX 5080 Founders Edition, 2x DDR5, one Gen5 and one Gen4 NVMe, 6 case fans, one AIO, ATX board

• Inputs: CPU = Ryzen 7 9800X3D (120W); GPU = RTX 5080 Founders Edition (360W peak); DDR5 sticks = 2; Gen5 NVMe = 1; Gen4 NVMe = 1; Gen3 NVMe = 0; SATA SSDs = 0; HDDs = 0; case fans = 6; AIO = 1; USB/misc = 10W; motherboard = ATX (45W)
• Result: Peak draw 587W | Min recommended 750W | Sweet spot 1200W. Headline: “Minimum recommended PSU: 750W — your build peaks at 587W. For a 40–50% load target, the optional efficiency-focused size is 1200W (49% utilization), which sits in the 80 Plus efficiency sweet spot (40–50%).”

Homelab NAS / Proxmox box — Ryzen 5 5600X on a Micro-ATX board, no dedicated GPU, one NVMe boot drive and six 3.5-inch hard drives, four case fans, air cooler

• Inputs: CPU = Ryzen 5 5600X (65W); GPU = No dedicated GPU / integrated only (0W); DDR5 sticks = 2; Gen5 NVMe = 0; Gen4 NVMe = 0; Gen3 NVMe = 1; SATA SSDs = 0; HDDs = 6; case fans = 4; AIO = 0; USB/misc = 10W; motherboard = mATX (35W)
• Result: Peak draw 206W | Min recommended 550W | Sweet spot 550W. Headline: “Minimum recommended PSU: 550W — your build peaks at 206W. For a 40–50% load target, the optional efficiency-focused size is 550W (37% utilization).” (no sweet-spot clause)

PSU wattage by graphics card

In a balanced, gaming-first build the graphics card is the single largest draw — roughly 45% of system peak on an entry card and up to about 75% on a flagship — so it is the fastest way to a starting number. Every row below carries its own source, because two different kinds of number appear in this table and the difference matters.

Why the two bases differ. A vendor minimum is deliberately worst-case: NVIDIA’s own note on the RTX 5090 states its 1000W figure is based on a system built around a Ryzen 9 9950X — a flagship CPU, not a mainstream one — so the number carries padding for a processor you may not own. Our estimates are the opposite: the calculator’s itemized minimum for a typical mid-range build, stepped up one retail size. Both are floors. Where a vendor publishes a number, we print the vendor’s, because that is the configuration the card was validated against.

These are minimums, not the calculator’s answer. The tool below targets roughly half load rather than a floor, so its headline recommendation will read higher than this table — on a flagship build, considerably higher. That gap is efficiency and upgrade headroom, not a transient-spike requirement. If you want the smallest defensible unit, use this table; if you want the quietest and most efficient one, use the tool’s number. Note also that 600W is a size few brands actually sell — where a vendor figure lands between retail steps, buy the next size up. For a worked example of how one card’s number changes with the processor beside it, see the RTX 50-series PSU guide — per-card tables for the 5070 through the 5090, including the one case where the itemized math lands above NVIDIA’s own floor.

How this power supply calculator works

No vendor’s calculator shows you its math. Here is ours, in full.

1. It sums real component draw, not a flat overhead. Your CPU and GPU peak figures come from the dropdowns; everything else is itemized and added: motherboard (about 45W for ATX, less for Micro-ATX and Mini-ITX, more for EATX), 5W per stick of RAM, 10W per Gen5 M.2 drive, 8W per Gen4, 6W per Gen3, 3W per SATA SSD, 12W per hard drive, 2W per case fan, 12W for an AIO pump and fans, plus whatever you enter in the miscellaneous field (10W by default, for fan controllers, RGB, capture cards, and similar). That total is your peak draw.

2. The minimum is peak plus 20%. The calculator multiplies your peak by 1.2 and rounds up to the next size commonly sold — 550, 650, 750, 850, 1000, 1200, or 1500W; above 1500W it steps in 100W increments, because retail sizes get irregular there. That is the smallest unit it will suggest, and it is a genuine floor: at exactly 1.2x, your peak sits at about 83% of the unit’s rating, which is above the 80% line where the table below starts warning. Treat the minimum as “this will work,” not “this is the one to buy.”

3. The recommended size targets about half load. Power supplies are most efficient, coolest, and quietest loaded near the middle of their range, so the headline recommendation is the size that puts your peak near half the unit’s rating, and the tool flags 40-50% as the sweet spot when your build lands there. It is deliberately larger than the minimum: it buys efficiency, quiet, and room for a future graphics card. It is not a spike requirement — see below.

4. The efficiency table shows every size. Rather than hiding the trade-off, the table rates each retail wattage against your build: above 80% load is under-sized and risks shutdowns, 65-80% works but leaves little upgrade room, and 35-65% is the band worth buying into.

The transient-spike question, answered honestly

Modern graphics cards pull microsecond spikes well above their rated power, and this is where PSU advice usually turns into “buy double.” It should not.

Intel’s ATX 3.0 design guide sets explicit excursion brackets a compliant unit must survive, and they are tiered by duration rather than being one blanket number:

The qualifier matters as much as the number. That 200% bracket applies to units above 450W that ship a native 12VHPWR / 12V-2x6 connector. A smaller unit, or one without that connector, is held to a lower bar — 150% at 100 µs. So “my PSU is ATX 3.x, it handles 200% spikes” is only true for the larger, natively-connectored units.

Where it applies, though, it settles the sizing question: a 750W unit in that class is built to ride out a 1500W spike lasting 100 microseconds. That headroom is already in the standard, so on a qualifying unit you do not buy a bigger PSU to cover transient spikes — you buy a compliant one. On an older ATX 2.x unit paired with a high-wattage card, leave more room, because it was never designed to these brackets.

What ATX 3.1 revised is the connector: the 12V-2x6 design shortens the sense pins so a plug that is not fully seated fails to deliver full power rather than making partial high-resistance contact. We are still not going to tell you whether 3.1 raises or lowers the transient bar relative to 3.0, because we have not read a source that compares the two brackets directly, and we do not publish spec claims we have not read. Buy 3.1 for the connector. (We have since read Intel’s ATX v3 design guide for a different figure — the low-load efficiency point it sets at 10W — which is covered in the PSU tier list.)

One more that vendor calculators skip: if your unit is multi-rail, total wattage is not a single pool. A 1000W multi-rail supply may cap one 12V rail well below the card’s draw, and a high-wattage GPU fed entirely from that rail can trip over-current protection on a supply that is nominally huge. Follow the rail distribution in your PSU’s manual and use separate cables rather than daisy-chaining one pigtail.

Reading the three numbers

Continuous vs. peak vs. transient. A PSU’s headline number is its continuous rating — what it can deliver all day. Your parts list a peak draw, which the calculator sums. Transient spikes are the third number, and the standard above covers them. A unit sized only to the raw continuous total, with no margin at all, can trip its over-current protection under load, which shows up as a random shutdown rather than an error message.

Why the sweet spot is roughly half load. Efficiency curves peak in the middle of a unit’s range, and a supply loafing at half load runs cooler and spins its fan slower — often not at all, on units with a zero-RPM mode. Worth keeping the two measures apart: the calculator’s load percentages are measured against your peak, while the 50-60% figure people quote describes typical sustained draw, which sits below peak. Size so peak stays under about 80% and typical lands near half, and both are satisfied at once.

80 Plus tiers in plain terms. The 80 PLUS badge rates efficiency at fixed load points. At these wattages the bill difference between Gold and Platinum is a dollar or two a month; treat the rating mostly as a signal of build quality, heat, and fan noise. Gold is the floor worth buying for a gaming or always-on homelab box. Our EVGA SuperNOVA 1000 GT review walks through what that looks like in a real unit, and the power & cost calculator turns watts into an annual dollar figure.

A lower-power build is a cheaper build. Undervolting cuts real wattage — around 100W on a high-end card and roughly 50W on a mid-range one, going by the measured results in our own database — which can drop you a PSU size and lower your bill at the same time. The complete GPU undervolting guide covers the method, and our undervolt results database lists measured power savings by card.

If your PC is already shutting down

An undersized or failing supply looks the same from the outside: reboots under load, shutdowns in games, a PC that will not post. PSU failure symptoms covers how to tell a dying unit from an undersized one, and the FAQ below covers testing a supply and finding out which one you already own.

These are conservative component estimates. Real-world idle draw is far lower, and your actual numbers depend on overclocks and the specific models you choose — for a full parts list with compatibility checking, use the PC Builder, and for where each card lands on speed, see the GPU hierarchy.

Corrections

2026-08-15 — Core i7-14700K peak draw corrected from 192W to 253W. The CPU dropdown is documented above as carrying peak figures, and its other Intel entries do exactly that: the i9-14900K and i9-13900K rows both use 253W, which is Intel’s published Maximum Turbo Power for those parts. The i7-14700K row carried 192W, which matches neither of Intel’s two published power figures for that processor — Intel ARK lists it at 125W Processor Base Power / 253W Maximum Turbo Power (read from Intel’s own specification page on 2026-08-15). The 61W understatement flowed straight into every calculation a 14700K owner ran, pushing peak draw, the minimum size and the recommended size all low. Corrected to 253W, which restores the table’s own Intel convention.

Scope note, stated plainly: this correction covers the one row re-derived from the vendor page. Several other rows in the same dropdown appear to carry base TDP where the page promises peak — AMD entries in particular, whose peak package power (PPT) AMD does not publish on its product pages. Those are recorded as open findings in our audit log rather than changed on a guess; see the caveat below.

2026-08-29 — three Intel rows corrected from base power to Maximum Turbo Power. The same defect class as the 14700K entry above, in three more rows: Core i5-14600K and Core i5-13600K both carried 125W, and Core Ultra 5 245K carried 125W. In every case that is Intel’s Processor Base Power, not the peak figure this dropdown is documented as carrying. Corrected to Intel’s published Maximum Turbo Power — 181W for the i5-14600K and i5-13600K, 159W for the Core Ultra 5 245K. The understatement was worth one retail PSU size on mainstream pairings: an i5-13600K with an RTX 5070 Ti computed 514W and recommended a 650W unit, where the true 570W peak recommends 750W — and 570W of 650W is 88% load, which this page’s own efficiency table would flag as “Over — risk of shutdowns under peak load”.

Change-safety note: correcting these three removed the last value="125" option from the CPU dropdown. A shared link carrying cpu=125 would previously have landed on no option at all and silently computed with a 0W CPU. The URL restore path was hardened first, in the same change, to ignore any value the dropdown does not offer and keep its default selection instead.

Read the AMD rows as a mix of Default TDP and PPT — not a single convention. An earlier version of this note said every AMD figure was AMD’s published Default TDP. That was not true, and the rows disagree with each other: the Ryzen 9 9950X (200W) and 7950X (230W) rows carry PPT, the package power ceiling, which is the closer proxy for the peak draw this calculator sums; the Ryzen 5 7600X row carried 88W, which is neither that part’s 105W Default TDP nor its ~142W PPT; and the Ryzen 7 5825U row carries 45W against a published 15W Default TDP. Those rows are recorded as open findings and are being re-derived against primary sources rather than changed on a guess — deliberately including not lowering the 9950X and 7950X rows to their 170W thermal figure, which would make this paragraph true by understating the two highest-draw AMD parts. Until each row is re-derived, treat an AMD build’s calculated peak as approximate and lean toward the recommended size rather than the minimum.

Sources

• NVIDIA GeForce RTX 50-series official specifications (total graphics power and minimum system power requirement) — RTX 5090, RTX 5080, RTX 5070 family, RTX 5060 family — verified live 2026-07-24; the 5070 and 5060 family pages re-verified 2026-07-25.
• Intel ATX 3.0 / ATX 3.1 desktop power supply design guides — the 200%-of-rated power-excursion requirement for microsecond transients (Intel ATX 3.0 PSU power excursion).
• AMD board power: RX 9060 XT (150W) from the TechFuelHQ PC Builder parts dataset (CC BY 4.0); RX 9070 XT (304W) as cited in our RX 9070 XT undervolt guide; RX 9070 (220W) as cited in our RX 9070 vs RX 9070 XT comparison. The PSU sizes on those three rows are our own estimates, not AMD figures — AMD’s specification pages did not respond when we checked on 2026-07-24.
• Intel desktop processor power: Processor Base Power and Maximum Turbo Power from Intel ARK product specification pages — Core i7-14700K (125W base / 253W turbo), read 2026-08-15. The CPU dropdown carries the turbo figure, because the calculator sums peak draw.
• Component draw coefficients are this calculator’s own published figures, listed in full in the methodology section above.