How many times more does a desktop use than a laptop?

For the same task a laptop (20–65 W) uses about 2–3× less than an office desktop and 5–10× less than a gaming desktop, because laptop chips are efficiency-designed and there's no discrete GPU / separate monitor adding draw.

How much to leave a computer on overnight / 24 h?

At ~4 THB/unit: a 50 W laptop on 24 h ≈ 144 THB/month; a 150 W office PC ≈ 432; a 350–500 W gaming PC (genuinely under load) ≈ 1,000–1,440. Just idling with the screen on is far less — set sleep or turn it off when not in use.

How much per month is a gaming PC (powerful GPU)?

A gaming PC pulls 300–600 W while playing. At 4 h/day (~350 W) ≈ 168 THB/month; 8 h/day ≈ 336. A top-tier / overclocked GPU played longer runs higher. Capping FPS and using sleep helps.

Does a computer really use more power than the air-con?

Usually not: an air-con uses 1,000–2,000 W vs 80–180 W for an office PC, so run equally the air-con uses far more. But a powerful gaming PC (400–600 W) left on all day can total more than an air-con used only 2–3 h. It's watts × hours — compare on the air-con cost page.

Home Appliance Electricity Cost

How Many Watts Does a Computer / Laptop Use — and How Much a Month? PC vs Laptop vs Gaming

Name: CapSolar
Address: 429/44 Sukhonthasawat Rd, Lat Phrao, Bangkok, 10230, TH
Telephone: +66 2 124 5414
Price range: $$$$

Does a computer use a lot of power — how many watts, how much a month running all day/night, and is it true a PC uses more than the air-con? This page answers directly, splitting laptop / office PC / gaming PC with a discrete GPU, with a cost-by-hours-on table, how many times more a PC uses than a laptop, how much sleep mode saves, and the truth about the “a computer steals more power than the air-con” belief.

6 min readLast updated: August 2026As of: Aug 2026 — costed at ~4 THB/unit (rounded estimate)

A laptop uses about 20–65 watts; a general office desktop (with monitor) about 80–180 watts; a gaming / editing PC with a discrete GPU 300–600 watts (high-end / overclocked up to 750). Unlike a fridge, a computer is not duty-cycled — it draws its actual load wattage the whole time it is on, and only hits top wattage under heavy load (gaming/rendering), far less while typing/browsing. The cost is simple: power (kW) × hours on × 30 × ~4 THB. A 50 W laptop used 8 h/day ≈ 48 THB/month, but a 400 W gaming PC left on 24 h (load/download) tops 1,000 THB/month — so the culprit is not the box, it is high watts × long hours.

How Many Watts Does a Desktop PC Use (Work vs Gaming)?

A computer's power draw depends mainly on the GPU and CPU. A general office machine (integrated graphics) uses little; a gaming / editing machine with a discrete GPU uses several times more and only peaks under heavy load. The table below shows typical ranges from device / PSU specs (read the actual watts on your adapter/PSU):

How Many Watts Does a Desktop PC Use (Work vs Gaming)?
Device	Spec / use	Watts (in use)
Laptop	Work / study / streaming	~20–65 W
Desktop PC + monitor	Office (integrated graphics)	~80–180 W
Gaming/editing PC + monitor	Mid–high discrete GPU (under load)	~300–500 W
High-end / OC PC + monitor	Top-tier GPU (full load)	~500–750 W

The figures above are “in use” — a machine peaks only when gaming/rendering, and uses far less while typing or browsing. A monitor adds about 20–40 W (large / high-refresh more), and sleep mode falls to just ~2–5 W. For the whole-house picture, see the appliance electricity-cost table.

How Many Watts Does a Computer Use?

Short answer: a laptop ~20–65 W · a general office desktop with monitor ~80–180 W · a gaming/editing PC with monitor ~300–500 W · a high-end or overclocked machine ~500–750 W. These are “in use” figures, not a constant — unlike a fridge, a computer is not duty-cycled: it draws whatever the current task needs, peaking only while gaming or rendering and using far less while typing or browsing. A monitor adds roughly 20–40 W (large or high-refresh screens more), and sleep mode falls to just ~2–5 W. For your own machine's real figure, read the adapter (laptop) or the PSU (desktop) — the table above breaks it down by spec.

How Many Watts Does a Laptop Use — Is It a Lot?

A laptop uses about 20–65 watts — very little next to the rest of a household's appliances. At ~50 W that works out to roughly 24 THB/month at 4 h a day and 48 THB/month at 8 h a day. Against a desktop a laptop is cheaper to run by about 2–3× (versus an office PC) up to 5–10× (versus a gaming PC), because mobile chips are designed to survive on a battery, the small built-in screen uses little, and there is no high-power discrete GPU. Add roughly 20–40 W if you plug in an external monitor.

Running a Computer All Day / 24 h — How Much Per Month?

The arithmetic is direct: monthly PC cost = power (kW) × hours on per day × 30 × ~4 THB/unit. For example a 150 W office PC (0.15 kW) on 8 h/day = 0.15 × 8 × 30 × 4 = ~144 THB/month. The table compares by hours on (the 24-h column = left on day and night, e.g. downloading/rendering):

Running a Computer All Day / 24 h — How Much Per Month?
Machine (W)	~4 h/day	~8 h/day	On 24 h
Laptop ~50W	~24 THB	~48 THB	~144 THB
Office PC+mon ~150W	~72 THB	~144 THB	~432 THB
Gaming PC ~350W	~168 THB	~336 THB	~1,008 THB
High-end PC ~500W	~240 THB	~480 THB	~1,440 THB

The ~4 THB/unit is a round figure for easy math. Real home bills are tiered (more usage = higher per-unit) plus Ft + VAT. See the real rates at how many baht per unit, or compute the full bill at how to calculate your bill.

Note: the 24-h column assumes full watts the whole time, which overstates it if the machine just sits with the screen on — an idle PC uses far less than while gaming. But if it is genuinely under heavy load all day (downloading/rendering/mining), the four-figure numbers are real. That is where the “a computer steals power” belief comes from — not that every PC is a huge load, but that a powerful PC gets left running for long hours.

How Much Electricity Does a Computer Use Per Month?

At a normal 8 hours a day: a ~50 W laptop ≈ 48 THB/month · a ~150 W office PC + monitor ≈ 144 THB/month · a ~350 W gaming PC ≈ 336 THB/month · a ~500 W high-end machine ≈ 480 THB/month (at ~4 THB/unit). Halve those for 4 hours a day — the full rows are in the table above. The formula is power (kW) × hours on per day × 30 × ~4 THB. The short version: an ordinary work computer is not what inflates a bill (low hundreds of baht a month); a powerful gaming PC left running for long hours is the one that can reach four figures.

Leaving a PC On All Day — and All Night — Costs How Much?

Left on a full 24 h every day: a ~50 W laptop ≈ 144 THB/month · a ~150 W office PC ≈ 432 THB/month · a ~350 W gaming PC ≈ 1,008 THB/month · a ~500 W high-end machine ≈ 1,440 THB/month. “Left on overnight” is roughly 8 hours a night, so it matches the 8-h column instead: about 48 / 144 / 336 / 480 THB a month respectively. One caveat when reading these: the 24-h column assumes full watts the whole time, which overstates a machine that is merely sitting with its screen on — an idle PC uses far less than one that is gaming. But if it is genuinely under heavy load all day (downloading/rendering), the four-figure numbers are real.

PC vs Laptop — How Many Times More?

For the same task a laptop always uses less than a desktop — from about 2–3× (vs an office PC) up to 5–10× (vs a gaming PC), for these reasons:

Laptop chips are built for efficiency — mobile CPUs/GPUs draw far less than desktop parts of similar power, because they must run on a battery.

A discrete GPU is the gaming PC's main draw — one card can pull 150–350 W under load, several times a whole laptop. The heavier the game, the more it draws.

A PC's separate monitor adds power — a desktop needs a monitor (20–40 W); a laptop's small built-in screen uses far less. Plugging an external monitor into a laptop adds the same.

The power supply (PSU) and its efficiency — an 80 PLUS-rated PSU wastes less in conversion, trimming wasted watts — though it still won't make a powerful PC as frugal as a laptop.

Bottom line: for light work (docs/web/streaming) a laptop is clearly cheaper to run; for heavy work (gaming/editing/3D) a powerful PC naturally needs more power — matching the machine to the task is the best way to control the bill.

To compare with other home appliances (air-con, fridge, water heater) see the whole-house appliance electricity-cost table; or if the total bill is abnormally high, work through why your bill is expensive.

Sleep vs Shut Down — and Does a PC Really Use More Than the Air-Con?

The two most-asked questions about a computer's electricity cost:

Sleep vs shut down vs unplug: sleep falls to ~2–5 W (convenient, ready to resume); off-but-plugged is ~1–2 W (phantom load is tiny for a PC); unplugging cuts that but only saves a few baht a month — the real saving is not leaving the machine running at full when you're not using it. Set auto-sleep after 10–15 minutes idle.

Does a PC really use more than the air-con? Usually no — an air-con pulls 1,000–2,000 W vs 80–180 W for an office PC, so run equally the air-con uses several times more. But a powerful gaming PC (400–600 W) left on all day can total more than an air-con used only 2–3 h — it comes down to watts × hours, not the type of device. Compare directly on the air-con cost page.

Does a Computer Use a Lot of Power — Even Left Idle?

An ordinary work computer: no — a PC plus monitor is ~80–180 W, several times less than an air-con (1,000–2,000 W), and works out to roughly 144 THB/month at 8 hours a day. A gaming PC: genuinely yes — 300–500 W, reaching four figures a month if left running for long stretches. As for leaving it idle: it does draw power, but far less than in use — an idle machine uses much less than one under load, sleep mode falls to ~2–5 W, and off-but-plugged is ~1–2 W, which is a few baht a month. So the deciding factor is never whether the device is a computer, it is watts × hours.

How to Cut Your Computer's Electricity Cost

Because a computer's bill is “watts × hours on”, cutting it means reducing one or both:

Set auto-sleep / screen-off after 10–15 minutes idle, and use a “balanced/power-saver” plan instead of “maximum performance” for everyday tasks.

Don't leave it on 24 h without need — if you're not downloading/rendering, shut down or sleep overnight. This is the biggest saving for a powerful PC.

Use a laptop instead of a desktop for light work — for docs/web/video calls a laptop is several times cheaper, and lowering screen brightness helps more.

Right-size the spec/GPU to the task and cap the frame rate (FPS) — a GPU stronger than the task is electricity paid for nothing; capping FPS to what the monitor can show trims watts while gaming.

Switch off / unplug peripherals — monitors, speakers and printers that sip standby power add up. Use a switched power strip to cut them all at once.

Working from home, or running a gaming/rendering PC for long daytime hours + air-con = a big daytime bill — exactly when rooftop solar is generating. Ask CapSolar for a free assessment from your real bill.

About the Author

Compiled by the CapSolar team under Frank Lee (Founder). CapSolar is a commercial & industrial solar EPC/PPA provider in Thailand that explains electricity bills and energy use from first-principles arithmetic so households and businesses can decide with confidence.

FAQ

An office PC (integrated graphics) with a monitor is about 80–180 W; a gaming/editing PC with a discrete GPU is 300–600 W (high-end up to 750 W), peaking only under heavy load and using far less while typing/browsing. Read the actual watts on the PSU.

Appliance Electricity-Cost Table

Whole-house use across 30 appliances.

Chest Freezer Electricity Cost

By คิว, monthly cost, vs a fridge.

Air-Con Electricity Cost

The home's biggest load, vs a PC.

How to Cut Your Home Bill

Practical whole-house saving tips.

Working From Home or Running a PC for Long Hours — High Daytime Bill?

Computers, air-con and daytime devices are the big daytime bill — exactly when rooftop solar generates. CapSolar gives you a free assessment from your actual bill of whether it pays for your home or business.

Free Consultationor call +66 2 124 5414