{
    "name": "Horsepower Calculator",
    "url": "https://calculators.geekmidst.com/calculators/horsepower-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/horsepower-calculator.md",
    "category": "Science & engineering",
    "description": "Calculate power in horsepower, metric horsepower (PS), kilowatts and watts from torque and engine speed, or from force, distance and time.",
    "summary": "Power is the rate of doing work. For a rotating shaft it is torque times angular speed; for a straight push it is force times distance divided by time.",
    "also_called": [
        "Torque to horsepower calculator",
        "HP calculator"
    ],
    "applies_to": "Worldwide",
    "last_updated": "2026-10-29",
    "computation": "Results are computed in the visitor’s browser on the HTML page. This API describes the calculator; it does not compute results.",
    "inputs": [
        {
            "name": "mode",
            "label": "Calculate from",
            "type": "segmented",
            "default": "torque",
            "options": {
                "torque": "Torque and RPM",
                "work": "Force, distance and time"
            }
        },
        {
            "name": "torque",
            "label": "Torque",
            "type": "number",
            "default": "400",
            "shown_when": {
                "mode": "torque"
            }
        },
        {
            "name": "torque_unit",
            "label": "Torque unit",
            "type": "segmented",
            "default": "nm",
            "options": {
                "nm": "N·m",
                "lbft": "lb·ft"
            },
            "shown_when": {
                "mode": "torque"
            }
        },
        {
            "name": "rpm",
            "label": "Engine speed",
            "type": "number",
            "default": "6000",
            "unit": "rpm",
            "shown_when": {
                "mode": "torque"
            }
        },
        {
            "name": "force",
            "label": "Force",
            "type": "number",
            "default": "550",
            "shown_when": {
                "mode": "work"
            }
        },
        {
            "name": "force_unit",
            "label": "Force unit",
            "type": "segmented",
            "default": "lbf",
            "options": {
                "n": "Newtons",
                "lbf": "Pounds-force"
            },
            "shown_when": {
                "mode": "work"
            }
        },
        {
            "name": "distance",
            "label": "Distance moved",
            "type": "number",
            "default": "1",
            "shown_when": {
                "mode": "work"
            }
        },
        {
            "name": "distance_unit",
            "label": "Distance unit",
            "type": "segmented",
            "default": "ft",
            "options": {
                "m": "Metres",
                "ft": "Feet"
            },
            "shown_when": {
                "mode": "work"
            }
        },
        {
            "name": "seconds",
            "label": "Time taken",
            "type": "number",
            "default": "1",
            "unit": "s",
            "shown_when": {
                "mode": "work"
            }
        }
    ],
    "outputs": [
        {
            "key": "hp",
            "label": "Horsepower (mechanical)",
            "format": "number"
        },
        {
            "key": "kw",
            "label": "Kilowatts",
            "format": "number"
        },
        {
            "key": "ps",
            "label": "Metric horsepower",
            "format": "number"
        },
        {
            "key": "watts",
            "label": "Watts",
            "format": "number"
        }
    ],
    "formula": {
        "text": "P (W) = Torque (N·m) × RPM × 2π ÷ 60;  P = Force × Distance ÷ Time;  hp = W ÷ 745.69987;  PS = W ÷ 735.49875;  in US units hp = lb·ft × RPM ÷ 5,252",
        "variables": {
            "1 hp": "550 ft·lbf/s = 745.69987 W",
            "1 PS": "75 kgf·m/s = 735.49875 W",
            "1 lb·ft": "1.3558179 N·m"
        }
    },
    "worked_example": {
        "inputs": {
            "mode": "torque",
            "torque": "400",
            "torque_unit": "nm",
            "rpm": "6000",
            "force": "550",
            "force_unit": "lbf",
            "distance": "1",
            "distance_unit": "ft",
            "seconds": "1"
        },
        "steps": [
            "Angular speed: 6,000 rpm × 2π ÷ 60 = 628.32 rad/s.",
            "Power: 400 N·m × 628.32 = 251,327 W = 251.3 kW.",
            "In horsepower: 251,327 ÷ 745.7 = 337.0 hp, or ÷ 735.5 = 341.7 PS."
        ],
        "result": "400 N·m at 6,000 rpm is about 251 kW, 337 hp or 342 PS."
    },
    "interpretation": "Peak power usually occurs at higher rpm than peak torque. Quoted engine figures are measured at the crankshaft; power at the wheels is lower because of drivetrain losses.",
    "assumptions": [
        "Mechanical (imperial) horsepower of 745.7 W unless PS is stated."
    ],
    "limitations": [
        "Electrical horsepower (746 W) and boiler horsepower are different units and are not shown."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "Why do torque and horsepower curves cross at 5,252 rpm?",
            "answer": "In US units hp = lb·ft × rpm ÷ 5,252, because 33,000 ft·lbf per minute ÷ 2π ≈ 5,252. At that speed the two numbers are equal."
        },
        {
            "question": "Is PS the same as bhp?",
            "answer": "No. PS (metric horsepower) is 735.5 W, about 1.4% less than a mechanical horsepower. “bhp” means horsepower measured at the engine’s output shaft."
        }
    ],
    "sources": [],
    "related": [
        {
            "name": "Engine Horsepower Calculator",
            "url": "https://calculators.geekmidst.com/calculators/engine-horsepower-calculator"
        },
        {
            "name": "Ohm’s Law Calculator",
            "url": "https://calculators.geekmidst.com/calculators/ohms-law-calculator"
        },
        {
            "name": "Conversion Calculator",
            "url": "https://calculators.geekmidst.com/calculators/conversion-calculator"
        },
        {
            "name": "Mechanical Power Calculator",
            "url": "https://calculators.geekmidst.com/calculators/mechanical-power-calculator"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}