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Math & Numbers

Drag Force Calculator (F_D = ½·ρ·v²·C_D·A)

Compute the drag force on a body in a fluid stream: F_D = ½·ρ·v²·C_D·A (N), where ρ is the fluid density, v the free-stream velocity, C_D the drag coefficient (shape- and Reynolds-dependent), and A the reference (frontal projected) area. A built-in shape library supplies typical high-Re C_D values: sphere 0.47, hemisphere 0.42, long cylinder 0.81, disk/flat plate 1.17, cube 1.05, streamlined airfoil 0.04, long streamlined ellipsoid 0.07, cone 0.50; or choose 'Custom' to enter C_D directly. Optionally, with dynamic viscosity μ and characteristic length L, the Reynolds number Re = ρ·v·L/μ is computed, and the power dissipated by drag P = F_D·v (W). Density in kg/m³/g/cm³, velocity in m/s/km/h, area in m²/cm²/mm², length in m/cm/mm.

json· JSON resultOpen tool

Quick start

Call this tool from your code in three languages.

cURL
curl -X POST 'https://api.elysiatools.com/en/api/tools/drag-force-calculator' \
  -H 'Content-Type: application/json' \
  -d '{"shapeType":"sphere","dragCoeff":0.47,"density":1.225,"densityUnit":"kg/m3","velocity":20,"velocityUnit":"m/s","referenceArea":1,"areaUnit":"m2","dynamicViscosity":0,"charLength":0,"lengthUnit":"m","decimalPlaces":4}'

© 2026 Elysia Tools. Developer documentation.

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API reference

Send a POST request with your inputs as JSON. File parameters require a separate upload first.

Endpoint

HTTP
POST https://api.elysiatools.com/en/api/tools/drag-force-calculator

Parameters

NameTypeRequiredDescription
shapeTypeselectNoBody shape. Selecting a preset fills the typical drag coefficient C_D for that shape at high Reynolds number. Choose 'Custom' to enter C_D directly.
dragCoeffnumberYesDrag coefficient C_D (0 to 5). When a preset Shape is selected, the typical value is filled in automatically; you may still override it. Choose Shape = Custom to enter your own value.
densitynumberYesFluid density ρ. Enter in the selected Density Unit.
densityUnitselectNo—
velocitynumberYesFree-stream velocity v. Enter in the selected Velocity Unit.
velocityUnitselectNo—
referenceAreanumberYesReference (frontal projected) area A. Enter in the selected Area Unit.
areaUnitselectNo—
dynamicViscositynumberNoDynamic viscosity μ of the fluid in Pa·s. Optional — when supplied together with a characteristic length L, the Reynolds number Re = ρ·v·L/μ is computed.
charLengthnumberNoCharacteristic length L of the body. Optional — used only to compute Re. Enter in the selected Length Unit.
lengthUnitselectNo—
decimalPlacesnumberNo—

Response format

JSON result

JSON
{
  "key": {...},
  "metadata": {
    "key": "value"
  },
  "error": "Error message (optional)",
  "message": "Notification message (optional)"
}

MCP integration

Add this tool to your Model Context Protocol server so AI agents can list and call it.

Server configuration

Add this block to your MCP client configuration:

mcp.json
{
  "mcpServers": {
    "elysiatools-drag-force-calculator": {
      "name": "drag-force-calculator",
      "description": "Compute the drag force on a body in a fluid stream: F_D = ½·ρ·v²·C_D·A (N), where ρ is the fluid density, v the free-stream velocity, C_D the drag coefficient (shape- and Reynolds-dependent), and A the reference (frontal projected) area. A built-in shape library supplies typical high-Re C_D values: sphere 0.47, hemisphere 0.42, long cylinder 0.81, disk/flat plate 1.17, cube 1.05, streamlined airfoil 0.04, long streamlined ellipsoid 0.07, cone 0.50; or choose 'Custom' to enter C_D directly. Optionally, with dynamic viscosity μ and characteristic length L, the Reynolds number Re = ρ·v·L/μ is computed, and the power dissipated by drag P = F_D·v (W). Density in kg/m³/g/cm³, velocity in m/s/km/h, area in m²/cm²/mm², length in m/cm/mm.",
      "baseUrl": "https://api.elysiatools.com/mcp/sse?toolId=drag-force-calculator",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

List available tools

After connecting to the SSE endpoint, list the exposed tools:

tools/list
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/list"
}

Call this tool

Invoke the tool by its id, passing arguments built from its parameters:

tools/call
{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "drag-force-calculator",
    "arguments": {
  "shapeType": "sphere",
  "dragCoeff": 0.47,
  "density": 1.225,
  "densityUnit": "kg/m3",
  "velocity": 20,
  "velocityUnit": "m/s",
  "referenceArea": 1,
  "areaUnit": "m2",
  "dynamicViscosity": 0,
  "charLength": 0,
  "lengthUnit": "m",
  "decimalPlaces": 4
}
  }
}
Chain multiple tools in one session with a comma-separated toolId list, e.g. /mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp (max 20).

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