Assess Your Power Needs Before You Shop
Before you visit any store or browse online, calculate the wattage your household requires during an outage. Generators are not one-size-fits-all, and buying too small a unit leads to overload; buying too large wastes fuel and money.
Start with two calculations: running watts and starting watts. Running watts represent the continuous power an appliance needs. Starting watts, also called surge watts, apply to motor-driven devices—refrigerators, air conditioners, pumps—which draw extra power for a few seconds at startup. A typical refrigerator needs 700 running watts but 2,200 starting watts. A 1-ton air conditioner demands roughly 1,200 running watts and 3,500 starting watts.
List your essentials. Most households prioritize the refrigerator, freezer, sump pump, a few lights, and device chargers. Add the running watts, then add the highest single starting watt requirement. This total determines your minimum generator capacity. For example: refrigerator (700 running, 2,200 starting) + freezer (700 running, 2,200 starting) + lights (300) + sump pump (800 running, 2,000 starting) equals 2,500 running watts, but you need at least 4,400 starting watts to handle the refrigerator and freezer starting simultaneously.
As a practical benchmark, a 3,000-watt generator powers essentials for a small household. A 5,000–7,500-watt unit handles most homes with well pumps or central air. Whole-house backup demands 10,000 watts or more.
Select the Right Fuel Type
Portable generators run on gasoline, propane, or diesel, with dual-fuel and tri-fuel options available. Your choice affects storage, runtime, cost, and safety.
Gasoline
Gasoline generators dominate the market due to lower upfront cost and widespread availability. However, gasoline degrades within 12 months without stabilizer. Store fuel in OSHA-approved containers, limit quantities to local fire code allowances (often 25 gallons residential), and never store gasoline in basements or attached garages. Runtime typically reaches 8–13 hours on a single tank at 50% load.
Propane
Propane burns cleaner, stores indefinitely, and connects to standard 20-pound barbecue tanks or larger permanent tanks. A 20-pound tank yields roughly 5 hours at 50% load on a mid-size generator. Propane produces 10–15% less power than gasoline on the same engine, so size up accordingly. Dual-fuel generators offer flexibility—run gasoline when available, switch to propane for cleaner storage.
Diesel
Diesel engines last longer, handle heavy loads efficiently, and diesel fuel stores more stably than gasoline. These units cost more upfront and weigh substantially more. They suit users with diesel equipment already on-site or those needing extended daily operation.
| Fuel Type | Storage Life | Runtime (20 lb propane / 5 gal gas) | Typical Price Premium |
|---|---|---|---|
| Gasoline | 12 months | 8–13 hours | Baseline |
| Propane | Indefinite | 5 hours (20 lb tank) | +10–20% dual-fuel |
| Diesel | 12–24 months | Varies by tank | +30–50% |
Match Features to Real-World Use
Several features directly impact usability and safety. Evaluate each against your specific situation.
Inverter technology: Standard generators produce fluctuating power suitable for tools and appliances. Inverter generators produce clean, stable electricity safe for electronics—computers, medical devices, smart home systems. Inverters also run quieter (50–60 decibels versus 70–80) and throttle engine speed to match load, improving fuel efficiency by 20–40%. The trade-off: higher cost per watt, typically 2–3 times standard generators.
Electric start: Pull-starting a cold generator in a storm proves difficult for many users. Electric start adds convenience but requires a charged battery. Some models offer both.
Transfer switch compatibility: Never plug a generator directly into a wall outlet (backfeeding)—this electrocutes utility workers and violates electrical code. A manual transfer switch, installed by a licensed electrician ($500–$1,500), lets you power hardwired circuits safely. Confirm your chosen generator works with your planned switch; 30-amp and 50-amp twist-lock outlets are standard.
Carbon monoxide shutdown: Since 2020, portable generators sold in the United States must include CO sensors that shut down the engine when carbon monoxide concentrations become dangerous. Prioritize models with this feature regardless of purchase date.
Consider Weight, Portability, and Noise
“Portable” spans a wide range. A 2,000-watt inverter weighs 45–50 pounds—one person can lift it. A 7,500-watt standard generator exceeds 200 pounds and requires a wheel kit. Measure your storage space: garage shelf, shed, or dedicated enclosure. Account for the generator’s footprint with operating clearance—manufacturers specify minimum distances from structures (typically 5–10 feet) for ventilation and fire safety.
Noise restrictions matter, especially in dense neighborhoods. Many municipalities limit outdoor equipment to 65 decibels at property lines. Inverter generators under 60 decibels at quarter load meet most requirements. Standard open-frame generators at 75–80 decibels draw complaints and potential fines. Check your local noise ordinance before purchasing.
Calculate True Ownership Costs
The purchase price is only your first expense. Budget for:
- Professional installation: Transfer switch installation by a licensed electrician runs $500–$1,500 depending on panel location and circuit count.
- Maintenance: Annual oil changes, air filter replacement, spark plug service, and fuel system cleaning total $100–$200 in parts if you perform labor yourself. Professional servicing doubles that figure.
- Fuel storage infrastructure: Propane tanks, gasoline containers, fuel stabilizer, and possibly a storage cabinet add $100–$500 initially.
- Runtime costs: At 50% load, a 5,000-watt gasoline generator consumes roughly 0.75 gallons per hour. During a three-day outage running 12 hours daily, you burn 27 gallons—approximately $100 at current prices.
Make Your Purchase and Prepare
Buy from authorized dealers with established warranty support. Major manufacturers—Honda, Yamaha, Generac, Champion, Westinghouse—maintain parts networks and honor warranties through registered dealers. Avoid gray-market imports with incompatible voltage or unsupported warranties.
Upon delivery, run your generator monthly for 15–20 minutes under load. This prevents fuel system clogging, keeps the battery charged, and confirms readiness. Maintain a maintenance log with run hours, oil changes, and service dates. Store your unit with stabilized fuel or run it dry per manufacturer instructions, and keep the operator’s manual accessible.
Your portable generator represents a significant investment in household resilience. Proper selection ensures that investment performs when you need it most.