How to Size a Power Station for Your Apartment
Quick Answer
To size a power station for your apartment: (1) list the devices you need during an outage, (2) find each device's wattage, (3) multiply each wattage by the hours you'll run it to get watt-hours (Wh), (4) add them up, (5) add 20% as a buffer for inverter loss and headroom. For a typical 1-bedroom apartment covering essentials (router, laptop, lights, phone, CPAP) through an 8-hour night outage, you need roughly 800 to 1,000Wh. The Bluetti AC70 (768Wh, ~$329) covers most renters, and the Anker Solix C1000 (1,056Wh, ~$499) adds comfortable headroom.
The 5-Step Sizing Method
Step 1: List Your Priority Devices
Write down everything you'd want to power during an outage. Be realistic. Most apartment renters settle on: WiFi router, laptop or desktop, phone charger, a few lights, and a CPAP if applicable. Adding a mini-fridge is possible but significantly increases capacity needs.
Step 2: Find Each Device's Wattage
Check the nameplate on each device (usually on the bottom or back) for wattage or amps. If it shows amps, multiply by 120 (US voltage) to get watts. Alternatively, use the reference table below. For laptops and phones, use the charger's rated wattage, not the device's theoretical max.
Step 3: Estimate Daily Hours of Use
For each device, estimate how many hours you'll actually run it during a typical outage. A router runs 24/7. Your laptop might run 8 hours. Lights might run 6 hours. CPAP runs 8 hours overnight. A mini-fridge cycles on and off, so use average draw (not peak wattage) multiplied by 24 hours.
Step 4: Calculate Watt-Hours Per Device
Multiply each device's wattage by its hours of use:
Device Wh = Wattage × Hours
Add all device Wh together for your total load.
Step 5: Add a 20% Buffer
Multiply your total by 1.2. This accounts for inverter efficiency loss (roughly 85% efficiency, meaning 15% of stored energy is lost in conversion) and gives you headroom for unexpected loads or a longer-than-expected outage.
Recommended Capacity = Total Load Wh × 1.2
Common Apartment Device Wattages
| Device | Typical Wattage | Notes |
|---|---|---|
| WiFi Router | 10-15W | Runs 24/7 |
| Laptop (charging) | 45-65W | Use charger nameplate |
| Desktop PC | 150-350W | Varies greatly by GPU |
| External Monitor (24") | 20-35W | LED backlit |
| Smartphone (charging) | 10-20W | Fast charge = higher W |
| Tablet (charging) | 18-30W | iPad Pro up to 30W |
| LED Bulb (per bulb) | 8-12W | 60W equivalent |
| LED Floor Lamp | 20-40W | Multi-bulb |
| CPAP (no humidifier) | 30-50W | Varies by pressure setting |
| CPAP (with humidifier) | 60-110W | Doubles runtime needs |
| Mini-Fridge (4-6 cu ft) | 50-80W avg | Cycles; use avg not peak |
| Full-Size Fridge | 100-150W avg | Cycles; use avg not peak |
| Electric Fan (tower) | 40-60W | Most efficient cooling |
| Window AC (5,000 BTU) | 400-550W | 3-5x fan draw |
| Coffee Maker | 800-1,200W | Very high; brief use only |
| Microwave | 600-1,200W | Very high; brief use only |
Three Worked Examples
Example 1: Studio Apartment, Essentials Only
Goal: 8-hour overnight outage coverage for one person.
| Device | Watts | Hours | Wh |
|---|---|---|---|
| WiFi Router | 12W | 8 | 96Wh |
| Laptop | 55W | 6 | 330Wh |
| Smartphone | 15W | 2 | 30Wh |
| LED Lights (2 bulbs) | 20W | 5 | 100Wh |
| Total | 556Wh | ||
| + 20% buffer | 667Wh |
Recommended: Bluetti AC70 (768Wh, ~$329). Covers the load with 100Wh of real headroom.
Example 2: 1-Bedroom Apartment with CPAP
Goal: Full overnight coverage including CPAP, plus daytime essentials.
| Device | Watts | Hours | Wh |
|---|---|---|---|
| WiFi Router | 12W | 12 | 144Wh |
| Laptop | 55W | 8 | 440Wh |
| Smartphone | 15W | 2 | 30Wh |
| LED Lights (3 bulbs) | 30W | 6 | 180Wh |
| CPAP (no humidifier) | 35W | 8 | 280Wh |
| Total | 1,074Wh | ||
| + 20% buffer | 1,289Wh |
Recommended: Anker Solix C1000 (1,056Wh, ~$499) covers most of this load. Or EcoFlow Delta 2 (1,024Wh, ~$799). If budget is tight, the AC70 (768Wh) covers CPAP and essentials but will need recharging before the 12-hour mark.
Example 3: WFH 1-Bedroom with Desktop PC
Goal: Work through a full-day outage without interruption.
| Device | Watts | Hours | Wh |
|---|---|---|---|
| Desktop PC | 250W | 8 | 2,000Wh |
| Monitor (27") | 35W | 8 | 280Wh |
| WiFi Router | 12W | 8 | 96Wh |
| Smartphone | 15W | 1 | 15Wh |
| LED Lights | 20W | 8 | 160Wh |
| Total | 2,551Wh | ||
| + 20% buffer | 3,061Wh |
Honest assessment: A full desktop workstation drawing 250W for 8 hours requires 3,000Wh, which is above the consumer portable power station sweet spot ($300 to $500 range). The Anker Solix C1000 (1,056Wh) covers roughly 3.5 hours of desktop runtime, enough for short outages but not a full day. For a full-day desktop outage, you'd need a 3,000Wh+ unit like the EcoFlow Delta Pro ($1,500+). Alternatively, switching to a laptop (55W) instead of a desktop cuts the load by 80% and makes full-day coverage trivially achievable with a $329 to $499 unit.
Don't Forget Output Wattage
Capacity (Wh) tells you how long the station lasts. Output (W) tells you what it can actually run. Before finalizing your pick, verify two things:
Continuous output covers your simultaneous load. Add up the wattage of everything you plan to run at the same time. If router + laptop + lights + CPAP = 112W, any station rated for 1,000W continuous handles it fine. Issues arise when people try to run a coffee maker (1,000W) or microwave (800W) from a 300W-output station.
Peak (surge) output covers motor startups. Compressor-driven devices (fridges, AC units) surge to 2 to 4 times their running wattage at startup. A mini-fridge drawing 80W steady might spike to 300 to 400W for 1 to 2 seconds. Your station needs enough peak output to handle that spike without shutting off. The Bluetti AC70 handles 2,000W surge; the Anker Solix C1000 handles 4,800W surge.
Quick-Reference Size Tiers
| Capacity | Best For | Example Model | Price |
|---|---|---|---|
| 256-320Wh | Phones, router, laptop for 3-5 hrs | EcoFlow River 2 | ~$249 |
| 512Wh | Essentials for 6-8 hrs (no CPAP) | Various mid-tier | ~$300-350 |
| 768Wh | Full essentials + CPAP overnight | Bluetti AC70 | ~$329 |
| 1,024-1,056Wh | Full essentials + CPAP + mini-fridge buffer | Anker Solix C1000 | ~$499 |
| 2,000Wh+ | Full-size fridge for several hours, extended coverage | EcoFlow Delta Pro 2 | $1,500+ |
Frequently Asked Questions
How many watt-hours do I need for an apartment power outage?
For a typical 1-bedroom apartment covering essentials (router, laptop, lights, phone, CPAP) through an 8-hour overnight outage, you need roughly 800 to 1,100Wh after a 20% buffer. The Bluetti AC70 at 768Wh covers this for most people. Add a mini-fridge and you need 1,200 to 1,500Wh. Studios can get by with 500 to 700Wh for short outages. Two-bedroom apartments or setups with a full-size fridge need 2,000Wh or more for meaningful all-day coverage.
How do I calculate the watt-hours I need?
Multiply each device's wattage by the hours you'll run it during an outage. Add up all device watt-hours. Multiply the total by 1.2 (20% buffer for inverter loss and headroom). That's your recommended minimum capacity. For example: router (12W x 8h = 96Wh) + laptop (55W x 6h = 330Wh) + lights (20W x 5h = 100Wh) + CPAP (35W x 8h = 280Wh) = 806Wh total. Add 20% = 967Wh. A 1,000Wh station covers you comfortably.
Is 1,000 watt-hours enough for an apartment?
Yes, for most apartment outage scenarios. 1,000Wh covers a CPAP all night (8 hrs at 35W = 280Wh), a router for 24 hours (12W x 24 = 288Wh), a laptop for most of the day (55W x 8h = 440Wh), and lights (20W x 5h = 100Wh) — roughly 1,100Wh total. Without the CPAP, 1,000Wh comfortably covers an entire day of apartment essentials. With a mini-fridge added, you'd want 1,500Wh or more for a full-day outage.