How Many Watts Does a Modem Use?
ZacharyWilliamA typical stand-alone cable/DSL/fiber modem uses about 5–15 watts, and even an all-in-one gateway with Wi-Fi is usually under ~20 W. See measured examples in The Power Consumption Database (Cable Modems) and Comcast’s public Small Network Equipment efficiency site.
1. Why modem wattage matters
Internet uptime is essential for work, calls, and smart-home devices. Because modems sip power, they’re perfect to keep online with a small UPS or a portable power station during outages or while camping.
2. So… how many watts does a modem use?
- Most DOCSIS 3.0/3.1 cable modems: 6–10 W typical. Examples: ARRIS SB8200 5.9 W measured, Motorola MB8600 ~6 W measured (17 W at boot for ~5 s).
- Multi-gig models (2.5G ports / more channels): plan ~10–20 W. Motorola MB8611 is listed as 18 W.
- Modem-router gateways: commonly ~10–20 W; e.g., Xfinity XB7 ~13.2 W measured.
Budgeting tip: Use 15 W for a modem or 25 W for a gateway if you need a safe planning number.
3. Wattage table of popular modems / gateways
The table consolidates popular U.S. models with the best available public measurements or manufacturer/datasheet references.
| Brand | Model | Type | Power (W) | Source / Notes |
|---|---|---|---|---|
| ARRIS | SB8200 | DOCSIS 3.1 modem | ~5.9 W | TPCDB measurement · Product page: ARRIS |
| Motorola | MB8600 | DOCSIS 3.1 modem | ~6.0 W avg; ~17 W at boot |
TPCDB measurement · Datasheet: PDF |
| Motorola | MB8611 | DOCSIS 3.1 multi-gig | ~18 W | ApprovedModemList · Specs: Motorola |
| NETGEAR | CM1000 | DOCSIS 3.1 modem | ~8.6 W | TPCDB measurement · Datasheet: PDF |
| Comcast / Xfinity | xFi Gateway XB7 | Modem + Wi-Fi | ~13.2 W | TPCDB measurement · Energy info: CableLabs SNE |
| TP-Link | TC-7610 | DOCSIS 3.0 modem | Adapter 12V/1A (max) | Datasheet shows 12V⎓1A (typical draw is lower in use) |
| ARRIS | S33 | DOCSIS 3.1 modem | — (not published) | Product page: ARRIS (no official watts listed) |
| ARRIS | G34 | DOCSIS 3.1 + Wi-Fi 6 | Varies (Wi-Fi radios add draw) | Product page: ARRIS |
| Cisco | DPC3941T | Gateway | ~13 W (op.); up to 17 W | TPCDB measurement · Spec listing: SHI |
Tip: If your exact model isn’t here, check the power adapter label. “12V 1A” means a max rating of 12 W—actual draw is often 5–9 W for pure DOCSIS modems. For certainty, measure with a plug-in watt-meter.
4. How to estimate monthly power cost
Energy (kWh) = (Watts × Hours per day × 30) ÷ 1,000
Example: 10 W modem, 24 h/day → 10 × 24 × 30 ÷ 1,000 = 7.2 kWh/month. At $0.15/kWh, that’s about $1.08/month.
5. Running a modem on a portable power station
Because a modem is a 10–20 W load, it’s a perfect match for compact LiFePO₄ power stations.
Runtime (h) ≈ Battery capacity (Wh) × 0.85 ÷ Modem watts
UDPOWER official capacities/specs for reference: S1200 1,190 Wh / 1,200 W, C600 596 Wh / 600 W, C400 256 Wh / 400 W, C200 192 Wh / 200 W. Add solar recharging with the UDPOWER 120W panel.
| Load | Watts | S1200 (1,190 Wh) | C600 (596 Wh) | C400 (256 Wh) | C200 (192 Wh) |
|---|---|---|---|---|---|
| Basic cable modem | 8 W | ≈ 126 h | ≈ 63 h | ≈ 27 h | ≈ 20 h |
| Gigabit modem (multi-gig chip) | 15 W | ≈ 67 h | ≈ 34 h | ≈ 14 h | ≈ 11 h |
| Gateway (modem+Wi-Fi) | 20 W | ≈ 50 h | ≈ 25 h | ≈ 11 h | ≈ 8 h |
6. UDPOWER options (light recommendation)
S1200 Portable Power Station
Official page — 1,190 Wh LiFePO₄, 1,200 W AC output, fast charge ~1.5 h.
C600 Portable Power Station
Official page — 596 Wh, 600 W rated, 1,200 W max, 4,000+ cycles, 5-year warranty.
C400 Portable Power Station
Official page — 256 Wh, 400 W (800 W surge), compact backup for modem + a few devices.
C200 Portable Power Station
Official page — 192 Wh, 200 W pure sine, ideal for modem + phone charging.
Optional solar recharge: UDPOWER 120W Portable Solar Panel.
7. FAQ
Does a modem use power when no one is browsing?
Yes. It stays synced to the ISP and keeps RF/optical circuitry active; measured idle draws for many models are in the 5–15 W range (see TPCDB).
Why does my model use more than 20 W?
It’s likely a gateway (modem + Wi-Fi radios) or a multi-gig design. Examples include MB8611 (~18 W) and gateways like XB7 (~13.2 W).
Can I power a modem from a portable power station?
Yes. Because draw is low, even a 192 Wh unit (UDPOWER C200) can keep it running many hours. Ensure the AC adapter voltage matches.
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