Your electric bill says 886 kWh. A new Tesla Model Y has a 78 kWh battery. A small commercial building uses about 20 MWh per month. A hyperscale Google data center pulls 50–100 MW continuously, totalling roughly 870 GWh per year. A single offshore wind turbine generates 15 MWh on a windy day. Five different units describing one physical quantity (energy), at five different scales — and the relationships between them are simple multiplication by 1,000 each step up. This guide explains the conversions, the all-important power-vs-energy distinction, and where each unit shows up in 2026.
Quick answer: 1 MWh = 1,000 kWh and 1 GWh = 1,000 MWh = 1,000,000 kWh. The “h” means watt-hours, an amount of energy used over time. kWh on your home bill, MWh on a commercial bill, GWh in utility planning, TWh for whole countries. The unit on a power-plant nameplate is MW or GW (no “h”) — that’s a rate; multiply by hours to get the energy generated.
Jump to a section
- The conversion ladder (Wh → kWh → MWh → GWh → TWh)
- Power vs energy — kW vs kWh, the critical distinction
- Reference table — full unit conversions
- Residential scale: kWh on your bill
- EV scale: kWh in batteries and charging
- Commercial scale: MWh demand and MW peak
- Utility scale: MWh generation and GW capacity
- Data centers and AI: MW per facility, GWh per year
- Solar and wind in MWh per year
- Use the xconvert MWh to kWh tool
- FAQ
The conversion ladder (Wh → kWh → MWh → GWh → TWh)
Each step up is a factor of 1,000:
Memorise the four step-ups (kilo / mega / giga / tera = each ×1,000) and you can move freely between any pair. The same prefixes are used for everything that has SI units — watts (power), bytes (storage), joules (energy), hertz (frequency) — so the multiplier is always the same.
A useful identity: 1 kWh = 3,600,000 joules (a kWh is just power applied over time — 1 kilowatt × 3,600 seconds × 1 second-of-watt-per-joule).
Power vs energy — kW vs kWh, the critical distinction
This trips people up constantly:
- Power (W, kW, MW, GW) is a rate — how much energy you’re using right now. Like miles per hour.
- Energy (Wh, kWh, MWh, GWh) is an amount — how much energy you’ve used over time. Like total miles travelled.
A 1,500 W microwave running for 30 minutes consumes 0.75 kWh of energy (1.5 kW × 0.5 h). The microwave’s power is 1,500 W; the energy it uses depends on how long you run it.
| Power unit | What’s typically rated in it |
|---|---|
| W (watt) | LED bulb (10 W), Wi-Fi router (15 W) |
| kW (kilowatt) | Hair dryer (1.5 kW), electric car charger (7–22 kW), home solar inverter (5–10 kW) |
| MW (megawatt) | Industrial motor, small wind turbine (1–3 MW), data center building (10–100+ MW) |
| GW (gigawatt) | Nuclear plant (1 GW), national grid demand (US: ~700 GW peak), hyperscale data-center cluster |
| Energy unit | What’s typically reported in it |
|---|---|
| Wh / kWh | Home electric bill (kWh), EV battery (kWh), small appliance use |
| MWh | Commercial / industrial bill, single battery storage unit (Tesla Megapack: 3.9 MWh) |
| GWh | Annual generation of a wind farm, monthly fuel use of a power plant |
| TWh | Total national / continental electricity use (US: ~4,000 TWh/year) |
On a power-plant nameplate “500 MW” is the rate. Operating at that rate for 1 hour generates 500 MWh. Operating for 24 hours at full output generates 12 GWh. Operating for a full year at a typical capacity factor of 50% generates about 2,200 GWh = 2.2 TWh.
On your home electric bill, “750 kWh” is the total energy you consumed over the billing period — there’s no “h” on the kW because the kWh already bakes in the time component.
Reference table — full unit conversions
| From | Wh | kWh | MWh | GWh | TWh |
|---|---|---|---|---|---|
| 1 Wh | 1 | 0.001 | 1e-6 | 1e-9 | 1e-12 |
| 1 kWh | 1,000 | 1 | 0.001 | 1e-6 | 1e-9 |
| 1 MWh | 1,000,000 | 1,000 | 1 | 0.001 | 1e-6 |
| 1 GWh | 1,000,000,000 | 1,000,000 | 1,000 | 1 | 0.001 |
| 1 TWh | 1,000,000,000,000 | 1,000,000,000 | 1,000,000 | 1,000 | 1 |
For values between units (e.g., 47,500 kWh in MWh = 47.5 MWh), use the xconvert MWh to kWh tool for precision.
Residential scale: kWh on your bill
The unit you see on every residential electric bill in the US, UK, EU, Australia, and most other countries is the kWh. Reference benchmarks (2024–2026):
| Source | Average kWh / month |
|---|---|
| US household average (EIA) | 886 kWh (10,791 kWh/year) |
| UK household average (Ofgem) | ~242 kWh (2,900 kWh/year) |
| EU average | ~330 kWh (3,960 kWh/year) |
| Texas / Arizona / Florida summer | 1,100–1,500 kWh (AC load) |
| California winter (mild climate) | 500–700 kWh |
| Northeast winter (resistive heat) | 1,500–2,500 kWh |
The US-vs-UK gap is mostly down to climate (larger AC and dryer loads in the US summer) and home size (US average ~204 m² vs UK ~95 m²). Per the US Energy Information Administration, the average US residential rate hovered around $0.16/kWh in 2024–2025, putting the typical monthly bill around $137–145.
To estimate a single appliance’s monthly contribution:
A 1,500 W space heater running 8 hours/day for a month: 1.5 × 8 × 30 = 360 kWh. At $0.16/kWh, that’s $57.60 added to the bill for one heater.
EV scale: kWh in batteries and charging
EV battery capacity is universally specified in kWh — this is the energy storage; range comes from dividing by miles-per-kWh efficiency.
| 2026 EV | Battery (kWh) | EPA range | Efficiency (mi/kWh) |
|---|---|---|---|
| Tesla Model 3 RWD | 60 (LFP) | 272 mi | 4.5 |
| Tesla Model Y Premium RWD | 78.4 | 311 mi | 4.0 |
| Tesla Model Y L (Long Range AWD) | 82 | 327 mi | 4.0 |
| Lucid Air Pure | 84 | 420 mi | 5.0 (most efficient) |
| Rivian R2 Performance | 88.67 (usable) | 332 mi | 3.77 |
| Tesla Model S Plaid | 100 | 359 mi | 3.6 |
| Ford F-150 Lightning ER | 131 | 320 mi | 2.4 |
| Hummer EV | 212.7 | 314 mi | 1.5 (heaviest) |
Charging cost math: the rate is published in $/kWh. A 78 kWh full charge at home (US average $0.16/kWh off-peak) costs $12.48. At a Tesla Supercharger in California ($0.42/kWh average), the same full charge costs $32.76. That’s why home charging dominates EV economics: 60–75% cost reduction vs public DC fast charging.
Charging speed is in kW (power) — separately from battery size. A 7 kW Level 2 home charger adds about 1 hour of energy for every 7 kWh delivered. A 250 kW DC fast charger adds 250 kWh per hour at peak — though the EV’s onboard charger and battery thermal limits usually constrain the actual rate.
Commercial scale: MWh demand and MW peak
Commercial and industrial electric bills introduce a second unit: kW or MW peak demand, in addition to total kWh / MWh consumption. Utilities charge for both because peak demand drives grid capacity costs.
Typical commercial monthly profiles:
- Small office building (10,000 sq ft): 20–40 MWh/month, ~50–100 kW peak demand
- Restaurant: 5–15 MWh/month, ~30–50 kW peak
- Mid-size grocery store: 50–100 MWh/month, ~150–300 kW peak (refrigeration)
- Big-box retail (Costco): 200–400 MWh/month, ~500 kW–1 MW peak
- University campus: 1,000–10,000 MWh/month, multi-MW peak
- Large hospital: 1,500–4,000 MWh/month, ~3–8 MW peak (24/7 critical load)
Demand charges (typically $10–25 per kW of peak demand per month) often equal or exceed the energy charges, which is why commercial buildings invest in load-shedding, battery storage, and solar — flattening the peak saves more than reducing total kWh.
Utility scale: MWh generation and GW capacity
Power-plant capacity is in MW or GW (a rate). Annual generation is in MWh, GWh, or TWh (an amount over time).
| Plant type | Typical capacity (MW) | Annual generation (GWh) | Capacity factor |
|---|---|---|---|
| Single offshore wind turbine | 15 MW | ~60 GWh | ~45% |
| Onshore wind farm (200 MW) | 200 MW | ~480 GWh | ~35% |
| Utility-scale solar farm (500 MW) | 500 MW | ~1,000 GWh | ~25% |
| Natural-gas peaker | 100 MW | ~50 GWh | ~5% (peak hours only) |
| Combined-cycle gas plant | 500 MW | ~3,000 GWh | ~70% |
| Nuclear reactor (single) | 1,000 MW | ~8,000 GWh | ~93% |
| Hoover Dam | 2,080 MW | ~4,000 GWh | ~25% (water-limited) |
Capacity factor is the ratio of actual energy generated to theoretical maximum (capacity × 8,760 hours/year). Nuclear runs near 24/7 (93%); wind and solar are weather-limited (25–45%). When comparing two plants, capacity in MW alone is misleading — multiply by capacity factor to get realistic annual GWh.
The US grid as a whole generates about 4,000 TWh/year with about 1,200 GW of installed capacity, averaging a ~38% system capacity factor across all source types.
Data centers and AI: MW per facility, GWh per year
The largest growth driver for electricity demand in 2024–2026 is data center buildout, especially for AI training and inference:
| Facility | Power (MW) | Annual energy (GWh) |
|---|---|---|
| Small colo / enterprise DC | 1–5 MW | 8–40 GWh |
| Mid-tier hyperscale | 20–50 MW | 175–440 GWh |
| Large hyperscale | 50–100 MW | 440–870 GWh |
| Hyperscale campus (multiple buildings) | 200–1,000 MW | 1,750–8,760 GWh |
The biggest single-site projects announced in 2024–2026 (Microsoft’s Wisconsin AI campus, Meta’s Louisiana cluster, xAI Memphis) target multi-gigawatt scale — comparable to a mid-size nuclear plant dedicated to compute alone.
The aggregate: US data centers consumed 176 TWh in 2023 (4.4% of national electricity), and the IEA projects global data center consumption could exceed 1,000 TWh by 2026 — more than the entire electricity consumption of Japan. By 2030, US data center demand alone could nearly triple.
This is why utility planners now think in GW of new generation needed per major hyperscaler buildout — each new 500 MW campus equals adding the demand of a city of 350,000 homes.
Solar and wind in MWh per year
Quick mental model for renewable scale:
- Residential rooftop solar (10 kW system): 12–18 MWh/year, depending on roof orientation and climate.
- Commercial rooftop / carport (1 MW system): 1,200–1,800 MWh/year (= 1.2–1.8 GWh).
- Utility-scale solar farm (100 MW): 200–250 GWh/year at typical US Southwest capacity factors.
- Single 5 MW onshore wind turbine: 12–15 GWh/year at ~30% capacity factor.
- Offshore wind turbine (15 MW, North Sea): 50–70 GWh/year at ~45% capacity factor.
A 10 kW home solar system at 15 MWh/year covers nearly twice the average US household’s 10.8 MWh/year consumption — which is why net-metering exists. The home consumes only when needed and exports the rest back to the grid.
Use the xconvert MWh to kWh tool
For precise conversions — sizing a battery, reading a commercial bill, calculating per-MWh costs — use xconvert’s megawatt-hours to kilowatt-hours converter. Each ×1,000 step up the ladder gives you the next unit:
- Kilowatt-hours to Megawatt-hours — reverse direction for residential-vs-commercial comparisons.
- Megawatt-hours to Gigawatt-hours — for utility-scale planning.
- Watt-hours to Kilowatt-hours — for small-appliance / phone-battery estimates.
- Joules to Kilowatt-hours — for cross-discipline (mechanical, thermal) energy comparisons.
Related explainer articles on the xconvert blog:
- kW vs HP: EV Motors, ICE Engines, and Power Standards — power-rating conventions (the rate side of energy).
- kJ vs kcal: Reading Food Labels Without a Calculator — energy-unit equivalent for food / metabolism.
- Bytes to GB: Binary vs Decimal Storage Units Explained — same SI prefix ladder applied to storage.
FAQ
What’s the difference between kW and kWh?
kW (kilowatt) is power — a rate. It’s how much energy you’re using right now. kWh (kilowatt-hour) is energy — an amount. It’s how much energy you’ve used over a period. A 2 kW heater running for 3 hours consumes 6 kWh. The “h” matters: kW is the rating; kWh is the cumulative consumption your meter records.
Why does my electric bill use kWh and my car charger spec use kW?
Your bill charges for total energy delivered (kWh). Your charger’s spec is its maximum power draw (kW). They’re different things: a 7 kW Level 2 charger delivers 7 kWh of energy in 1 hour, 14 kWh in 2 hours, etc. The cost on your bill depends on the kWh actually delivered, not the kW rating.
What’s a “demand charge” on my commercial bill?
In addition to per-kWh energy charges, commercial bills include a demand charge based on the highest 15-minute kW peak during the billing period. Utilities charge for peak demand because the grid has to be sized for the worst case. Demand charges often run $10–25/kW; a single high-load moment can dominate the month’s bill.
How does a Tesla Powerwall (kWh) relate to grid-scale battery storage (MWh)?
A single Tesla Powerwall stores about 13.5 kWh. A Tesla Megapack (utility-scale unit) stores about 3.9 MWh — roughly 290 Powerwalls worth. Hornsdale Power Reserve (the original Tesla “Big Battery” in Australia) is 150 MW / 194 MWh of storage. The largest 2024+ deployments hit 1+ GWh of storage.
Is 1 kWh enough to charge an iPhone?
Many times over. An iPhone 16 battery holds about 0.018 kWh (18 Wh). 1 kWh would charge an iPhone roughly 55 times. A typical laptop battery is around 0.05–0.1 kWh. The 1 kWh scale is appliance-and-up, not phone-and-down.
What’s a megawatt-hour worth in dollars?
At wholesale (what utilities pay), US bulk-power market prices average $30–60 per MWh (= $0.03–0.06/kWh). At retail residential rates (~$0.16/kWh in the US), 1 MWh is $160. Commercial industrial rates (~$0.08/kWh) put 1 MWh at about $80. The 3–4× gap between wholesale and retail covers transmission, distribution, billing, and grid maintenance.
Is “kw-h” the same as “kWh”?
Both refer to the same thing. The BIPM SI standard recommends “kWh” or “kW·h” (with the centered dot to indicate multiplication). “kw-h” and “Kw-hr” appear in informal writing and older documentation but are non-standard. Use kWh in technical writing.
Sources
Last verified 2026-05-25.
- US Energy Information Administration — Electricity Explained — primary US source for residential and sector electricity consumption.
- US EIA FAQ — How much electricity does an American home use? — 886 kWh/month residential average reference.
- BIPM — The International System of Units (SI Brochure) — primary definition of the watt, joule, and SI prefixes.
- IEA — International Energy Agency — global data center and electricity demand projections.
- NIST Special Publication 811 — Conversion Factors — Wh / joule / kWh conversion authority.