HP to Watts Explained: Conversion Formula, Examples, and Uses

When you see power ratings listed in horsepower but need the number in watts, things can get confusing fast. Whether you’re comparing motors, checking electrical requirements, or sizing equipment, converting HP to watts helps you work with numbers that actually line up.

This guide breaks down what horsepower and watts mean, shows you how the conversion works, and explains why it matters in everyday situations, without overcomplicating the math.

What Is Horsepower (HP)?

Horsepower, or HP, is a unit that measures power. It tells you how fast a machine can do work. In simple terms, more horsepower means a machine can do more work in the same amount of time.

The term goes back to the late 1700s. Engineer James Watt wanted an easy way to explain how powerful his steam engines were, so he compared them to draft horses. He estimated that a strong horse could lift 33,000 pounds one foot off the ground in one minute (33,000 ft-lb/min).

That reference stuck, and “horsepower” became a standard way to describe mechanical power. Using that definition, 1 horsepower equals about 745.7 watts.

You’ll see horsepower in plenty of everyday specs: car engines, electric motors, pumps, compressors, and some power tools. It’s especially common when you’re talking about a machine’s mechanical output—how much work it can deliver at the shaft—rather than the electricity it draws from the wall.

What Is a Watt (W)?

A watt (W) is the standard unit of power in the International System of Units (SI). It’s named after James Watt. A watt measures how quickly energy is used or produced. In plain terms, 1 watt = 1 joule of energy transferred per second.

Watts show up everywhere in daily life. Light bulbs, phone chargers, kitchen appliances, and power tools all list their power in watts. When you look at those numbers, you’re seeing how much power the device needs to run.

Watts are especially useful for electrical equipment because they tie directly to electricity. If you know the voltage and current, you can calculate wattage using a simple relationship:

Watts (W) = Volts (V) × Amps (A)

Even when a motor is labeled in horsepower, the electrical side of the spec sheet often lists watts (or kilowatts). That makes it easier to size circuits, estimate energy use, and compare equipment accurately.

How to Convert Horsepower to Watts

Most of the time in the US, “HP” or “horsepower” on a spec sheet means mechanical horsepower, sometimes called imperial horsepower. This is the standard used for engines and motor output.

By definition, 1 mechanical horsepower equals about 745.7 watts. (You may see the exact value written as 745.699871… watts, but it’s almost always rounded.)

The horsepower to watts formula

That makes the HP to watts conversion straightforward:

Watts ≈ Horsepower × 745.7

For quick estimates, many people round the value and say 1 horsepower to watts equals about 746W. In electrical contexts, electric horsepower (hpE) is also defined as exactly 746 watts

Quick examples:

• 0.5 hp ≈ 0.5 × 745.7 ≈ 372.8W
• 1 hp ≈ 1 × 745.7 ≈ 745.7W
• 2 hp ≈ 2 × 745.7 ≈ 1,491.4W
• 5 hp ≈ 5 × 745.7 ≈ 3,728.5 W
• 10 hp ≈ 10 × 745.7 ≈ 7,457W

If you’re working with electrical specs, you may want kilowatts:

• kW = watts ÷ 1,000
• So, 1 hp ≈ 0.746 kW (mechanical hp)

How to convert watts to horsepower

Sometimes you’ll start with watts and need horsepower instead, like when you’re comparing an appliance rating to a motor label. Just flip the math.

The watts to horsepower formula:

Horsepower ≈ Watts ÷ 745.7

Examples:

• 746W ≈ 1 hp
• 1,500W ≈ 2.01 hp
• 3,000W ≈ 4.02 hp

A quick note about what the number means

This watt and horsepower conversion links units, but it doesn’t automatically tell you how much power a device draws from the outlet.

For electric motors, horsepower usually describes mechanical output, while the electrical input is higher because of efficiency losses. That’s why a motor rated at 1 hp won’t always draw exactly 746 watts from the wall.

Other horsepower definitions worth knowing

Mechanical horsepower (hp) is the standard used in the United States for motors and machinery, and it’s the version most people mean when they say “horsepower.” That said, some spec sheets use other horsepower definitions, which can change the conversion slightly.

• Metric horsepower (PS or cv): Used in Europe and on some imported equipment. 1 PS ≈ 735.5 watts
• Boiler horsepower: Used only for boilers and heating systems. 1 boiler hp ≈ 9,809.5 watts

Unless a spec sheet clearly says PS, cv, or boiler horsepower, you can safely assume it’s using mechanical horsepower.

HP to Watt Conversion: Why It Matters in Real Life

Converting HP to watts isn’t just an academic exercise. It shows up in everyday decisions—especially when mechanical ratings and electrical limits don’t use the same units.

Knowing how to move between them helps you avoid guesswork and costly mistakes. Here’s why it matters:

Comparing motors and tools with different ratings

You’ll run into this often with motors and tools like air compressors, table saws, pumps, and shop vacs. Different products may list power in different units, which makes comparisons harder than they should be.

For example, imagine you’re comparing two air compressors. One is rated at 2 hp. The other lists 1,500 watts of output power. Without converting, it’s hard to tell how close they are. At a glance, the 1,500-watt model might even seem “stronger,” just because the number looks bigger.

But once you do the math, you see that:

• 2 hp ≈ 1,491 watts (mechanical output)

That doesn’t mean the 1,500W compressor will perform the same, but it tells you they’re in the same power range. From there, you can look at efficiency, duty cycle, and build quality instead of guessing based on labels.

Checking whether a motor fits a household circuit

Many home workshops and garages run on 120V, 15-amp or 20-amp circuits. Those circuits cap out at roughly 1,800 to 2,400 watts under ideal conditions.

If a motor is rated at 2 hp, converting HP to watts shows that its mechanical output alone is around 1,491W.

Once you factor in efficiency losses and startup current, that motor may be pushing the limits of a standard outlet. This kind of check helps you avoid nuisance breaker trips—or realize you need a dedicated circuit before installing the equipment.

Matching backup power to motor loads

When a storm is on the way, power math stops being academic. If your electricity goes out and your sump pump can’t run, a flooded basement can be the result. That’s where understanding HP to watts becomes critical.

Most household essentials—lights, Wi-Fi routers, refrigerators, phone chargers—are labeled in watts. But motor-driven equipment like sump pumps is usually rated in horsepower (HP). To know whether a backup power solution can handle the load, both numbers need to be compared in the same unit.

A common sump pump scenario

Let’s say you have a 1/2 hp sump pump, which is very common in residential homes.

• Mechanical output: 0.5 hp ≈ 373 watts

That number reflects output power, not electrical input. Once you factor in motor efficiency and power factor, a typical 1/2 hp sump pump usually draws around 600–800 watts while running.

Why surge power matters more than you think

Now comes the part many people miss. Sump pumps use induction motors, which require extra power when they start. This brief spike—called starting or surge wattage—is often 2 to 3 times the running load.

In real terms, that means a sump pump that runs at 700W may need 2,000 watts or more for a split second just to get the motor spinning. If your backup power source can’t supply that surge, the pump may fail to start, trip protection, or shut itself down.

Where portable power stations come in

Gone are the days when a loud, gas-chugging generator was your only option. Portable Power Stations (PPS) are essentially giant, sophisticated batteries with built-in inverters.

Unlike gas generators, you can run these inside your house. No carbon monoxide risk, no noise, and no storing stabilized gasoline.

Modern high-capacity units can now output 2,000W to 3,600W+ of continuous power, with surge capacities high enough to kick-start a heavy sump pump or a refrigerator.

The Anker SOLIX F3800 Portable Power Station is designed specifically to handle demanding home loads.

It offers:

• 6,000W continuous AC output
• 9,000W surge capacity
• 3,840 Wh battery capacity, expandable up to 26.9 kWh with 6 additional batteries

What that means in practice:

The 9,000W surge comfortably covers the startup spike of a typical residential sump pump. The 6,000 W continuous output leaves plenty of headroom once the pump is running.

You can power multiple essentials at the same time, such as:

• Refrigerator (~300W)
• Lights (~20–40W total)
• Wi-Fi router (~15W)
• Phones and laptops (~100W combined)

With 3,840 Wh of capacity, you get hours of runtime, depending on how often the pump cycles. And if you need more coverage, the system scales with extra batteries.

Turning a power station into a solar generator

Pair the F3800 with solar panels, and it becomes a solar generator, which is a major advantage during extended outages.

The F3800 supports up to 2,400W of solar input, allowing fast daytime recharging under good sunlight. Instead of watching your battery level drop, you can replenish power while still running critical equipment. For multi-day storm outages, that flexibility makes a real difference.

Conclusion

Converting HP to watts is a simple step that makes power ratings easier to compare and understand. Horsepower helps describe mechanical output, while watts connect that output to electrical limits and real-world use. Knowing how the two relate lets you read spec sheets more clearly, size equipment with fewer surprises, and avoid common misunderstandings. The math is straightforward, but the insight it gives you—especially when comparing tools, motors, or generators—is what really matters.

FAQs

Is 1 HP equal to 1000 watts?

No. In the US, horsepower usually means mechanical horsepower, which equals about 745.7 watts (often rounded to 746W). That means 1 HP is not the same as 1000W. One kilowatt (1000W) is actually about 1.34 HP, not the other way around.

Is 1 HP equal to 735 or 746?

It depends on the standard being used. In the US, 1 HP normally means mechanical horsepower, which is about 746 watts. The 735-watt figure refers to 1 metric horsepower (also called PS or cv), which is more common in Europe. Both are valid, but they’re based on different definitions. For US appliances, motors, and specs, 746 watts per HP is the correct value.

How many HP is a 2000W motor?

Using the standard US conversion for mechanical horsepower (1 HP ≈ 746 watts), a 2000W motor works out to about 2000 ÷ 746 ≈ 2.68 HP, or roughly 2.7 HP. That puts it in the high-power range, which is why motors of this size are often found in high-performance electric bikes and compact industrial or outdoor equipment.

How many watts is a 1 HP motor?

A 1 HP motor produces about 746 watts of mechanical power. However, the electrical power it draws is usually higher due to efficiency losses. For example, a 1 HP electric motor might consume 800–1000 watts from the outlet, depending on its efficiency, load, and design. Always check the motor’s input rating for real usage.

Why is 1 HP equal to 746 watts?

Because mechanical horsepower was defined historically as 33,000 foot-pounds of work per minute (or 550 foot-pounds per second). When you convert that definition into SI units, it equals about 745.7 watts, which is commonly rounded to 746 W for everyday calculations.