Hot Tub / Spa Wattage for Generator Sizing
About the Hot Tub / Spa
A standard 240-volt hot tub or spa with a heater, circulation pump, and jets. Hot tubs are among the most power-intensive residential loads, requiring both 240-volt service and substantial wattage. The starting surge comes from the pump motors engaging. Maintaining hot tub temperature during extended outages prevents potential freeze damage in winter climates, which can crack the shell and plumbing. A generator powering a hot tub needs at least 8,000 to 10,000 watts of capacity and 240-volt output capability.
Generator Sizing for a Hot Tub / Spa
Running a hot tub / spa by itself requires a generator with at least 9,375 W of capacity (10 kW), which includes a 25% safety margin. However, you rarely run a single appliance on a generator. When combined with other appliances, the hot tub / spa contributes 6,000 W to the continuous running load and adds a potential 1,500 W starting surge gap when its motor starts.
The hot tub / spa is an inductive (motor-driven) load with a starting surge of 7,500 W, which is 1.3 times its running wattage. This starting surge occurs for a fraction of a second when the motor first engages and must overcome inertia to begin rotating. Your generator must be capable of delivering this peak wattage even though it only lasts briefly. If the hot tub / spa has the largest starting surge gap of any appliance in your generator load, its surge gap of 1,500 W will be the primary driver of your peak demand calculation. Avoid starting the hot tub / spa at the same time as other large motor loads to prevent generator overload.
To determine the total generator size you need, use our interactive calculator to combine the hot tub / spa with your other appliances. The calculator automatically handles the starting surge calculation and applies the 25% safety margin to give you an accurate recommendation. Alternatively, browse the scenarios below to see common generator setups that include the hot tub / spa.
Scenarios That Include Hot Tub / Spa
The following pre-calculated generator scenarios include the hot tub / spa in their appliance list. Each scenario shows the total generator size needed for all appliances in the set, not just the hot tub / spa alone. Click any scenario to see the full appliance breakdown.
| Scenario | Total Appliances | Running Watts | Recommended Size |
|---|---|---|---|
| Pool and Spa Maintenance | 3 | 7,600 W | 12 kW |
Tips for Running a Hot Tub / Spa on a Generator
When running the hot tub / spa on a generator, the most important consideration is the starting surge. Before starting the hot tub / spa, check that no other large motor-driven appliances are starting simultaneously. Stagger your startups: let the hot tub / spa reach steady-state operation (usually within 1-2 seconds) before starting the next motor load.
If the generator struggles to start the hot tub / spa (indicated by the generator bogging down, lights dimming significantly, or the appliance failing to start), it likely means the generator's peak surge capacity is insufficient. Try reducing other loads before attempting to start the hot tub / spa again. If the problem persists, you may need a larger generator with more surge capacity.
Modern inverter generators handle motor starting surges particularly well due to their electronic power management. If you are purchasing a new generator specifically for loads that include the hot tub / spa, verify that the generator's peak (starting) wattage specification meets or exceeds the 7,500 W starting requirement plus the running wattage of all other connected appliances.
Hot Tub / Spa Wattage Compared to Similar Appliances
The following table compares the hot tub / spa to other appliances in the other category. Understanding relative power requirements helps you make informed decisions about which appliances to prioritize on your generator and where you might find opportunities to reduce your total load.
| Appliance | Running Watts | Starting Watts |
|---|---|---|
| Hot Tub / Spa (this appliance) | 6,000 W | 7,500 W |
| Phone / Tablet Charger | 25 W | — |
| Sewing Machine | 100 W | — |
| Clothes Iron | 1,200 W | — |
| Hair Dryer | 1,500 W | — |
| Electric Blanket | 200 W | — |
| Pool Pump (1 HP) | 1,500 W | 2,500 W |
Frequently Asked Questions
How many watts does a hot tub / spa use?
A hot tub / spa uses approximately 6000 watts of continuous (running) power during normal operation. It also requires 7500 watts of starting (surge) power when the motor first turns on, which is 1.3 times the running wattage. This starting surge lasts only a fraction of a second but your generator must be capable of delivering it.
What size generator do I need to run a hot tub / spa?
To run a hot tub / spa by itself, you need a generator rated for at least 9,375 W (10 kW), which includes a 25% safety margin above the starting wattage of 7500W. However, most people run additional appliances alongside the hot tub / spa, so your actual generator needs will be higher. Use our calculator to add your other appliances and get a comprehensive recommendation.
Can I run a hot tub / spa on an inverter generator?
Yes, a hot tub / spa can run on an inverter generator as long as the generator's peak (starting) wattage capacity meets or exceeds 7500 watts. Inverter generators handle motor starting surges well and provide clean power that is safe for the electronic controls found in many modern hot tub / spa models. Verify the inverter generator's surge rating in the specifications.