Fitness Calculator API - BMI & Calories

Health and fitness calculators: BMI with category and healthy weight range, BMR, daily calories (TDEE) with lose/maintain/gain targets, macros, ideal weight (4 formulas) and body fat (U.S. Navy method). Metric or imperial.

Authentication & base URL

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Endpoints

GET `/v1/health/bmi`

BMI

Parameter	In	Description	Example
`weight` *	query	Weight (kg, or lb if units=imperial)	`70`
`height` *	query	Height (cm, or inches if units=imperial)	`175`
`units`	query	metric or imperial	`metric`

GET `/v1/health/bmr`

Basal metabolic rate

Parameter	In	Description	Example
`weight` *	query	Weight (kg, or lb if units=imperial)	`70`
`height` *	query	Height (cm, or inches if units=imperial)	`175`
`units`	query	metric or imperial	`metric`
`age` *	query	Age in years	`30`
`sex` *	query	male or female	`male`

GET `/v1/health/calories`

Daily calories (TDEE)

Parameter	In	Description	Example
`weight` *	query	Weight (kg, or lb if units=imperial)	`70`
`height` *	query	Height (cm, or inches if units=imperial)	`175`
`units`	query	metric or imperial	`metric`
`age` *	query	Age in years	`30`
`sex` *	query	male or female	`male`
`activity`	query	sedentary, light, moderate, active, very_active	`moderate`

GET `/v1/health/macros`

Macros for a goal

Parameter	In	Description	Example
`weight` *	query	Weight (kg, or lb if units=imperial)	`70`
`height` *	query	Height (cm, or inches if units=imperial)	`175`
`units`	query	metric or imperial	`metric`
`age` *	query	Age in years	`30`
`sex` *	query	male or female	`male`
`activity`	query	Activity level	`moderate`
`goal`	query	lose, maintain or gain	`lose`

GET `/v1/health/ideal-weight`

Ideal weight

Parameter	In	Description	Example
`height` *	query	Height (cm or inches)	`175`
`sex` *	query	male or female	`female`
`units`	query	metric or imperial	`metric`

GET `/v1/health/body-fat`

Body fat (Navy method)

Parameter	In	Description	Example
`height` *	query	Height	`175`
`neck` *	query	Neck circumference	`38`
`waist` *	query	Waist circumference	`82`
`hip`	query	Hip circumference (female only)
`sex` *	query	male or female	`male`
`units`	query	metric or imperial	`metric`

Example

GET /v1/health/bmi?weight=70&height=175&units=metric

{
  "bmi": 22.9,
  "category": "Normal weight",
  "healthyWeightRangeKg": [
    56.7,
    76.3
  ],
  "note": "BMI is a screening measure for adults, not a diagnosis."
}

Use cases

Fitness and diet apps, gym and coaching platforms, health content sites, chatbots, onboarding questionnaires.

Why this API

Standard published formulas (Mifflin-St Jeor, Devine, Robinson, Miller, Hamwi, U.S. Navy).
Metric and imperial units, clear JSON, millisecond responses.
For information only, not medical advice.
Fair pricing: Free plan 500 requests/month, Pro 25,000 for $4.99, Ultra 150,000 for $14.99.

Support

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Pricing

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