ForHosting KIT · Health & fitness

TDEE & BMR calculator

An 80 kg, 180 cm, 30-year-old man with a sedentary routine burns 1,780 kcal at rest and needs 2,136 kcal a day to keep his weight, by the Mifflin-St Jeor equation. Enter sex, weight, height, age and activity to get your own figures. Free in your browser.

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Worked example

If you enter

Sex: Male
Weight (kg): 80
Height (cm): 180
Age (years): 30
Activity level: Sedentary

You get

Activity factor: 1.2
BMR: 1,780
TDEE: 2,136

Estimates basal metabolic rate and total daily energy expenditure from sex, weight in kilograms, height in centimetres, age and an activity level, using the Mifflin-St Jeor equation.

From resting burn to daily needs

The calculation runs in two steps. First comes basal metabolic rate, the energy your body would burn at complete rest, from the Mifflin-St Jeor equation: 10 times weight in kilograms, plus 6.25 times height in centimetres, minus 5 times age, plus 5 for men or minus 161 for women. For an 80 kg, 180 cm, 30-year-old man that gives 1,780 kcal. That figure is then multiplied by an activity factor to get total daily energy expenditure, the calories that keep weight stable: 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 active and 1.9 very active. Sedentary turns 1,780 into 2,136.

An anchor for a plan, not a prescription

The equation does not see body composition, hormonal state or the way metabolism adapts, so your real needs can differ from the estimate. Treat the number as the anchor of a plan rather than a fixed rule. Results are rounded to whole calories by default, with up to two decimals if you prefer. A frequent slip is choosing a higher activity level than your real routine, which inflates total daily expenditure and every target you work out from it.

Reading and applying the numbers

BMR is the energy your body would burn at complete rest; TDEE adds the cost of daily movement and exercise through the activity factor, so it is the realistic maintenance target. To lose or gain weight, clients typically create a deficit or surplus against tdee rather than against bmr. Because the equation ignores body composition, hormonal state and adaptive thermogenesis, the output is an estimate to anchor a plan, not a prescription.

What you can do with it

Nutrition and coaching apps

Turn a client profile into a maintenance calorie target, then apply a deficit or surplus against the returned tdee.

FAQ

Can I get decimal calories?

Yes. Set decimals from 0 to 2 (default 0); bmr and tdee are each rounded half-up independently from the raw value.

Is this medical advice?

No. It is a deterministic estimate that ignores body composition and metabolic adaptation; use it to plan, not to diagnose.

What is the difference between BMR and TDEE?

BMR is the energy your body would burn at complete rest. TDEE adds the cost of daily movement and exercise through the activity factor, so it is the realistic number of calories that keeps your weight stable.

Which activity level should I choose?

Pick the one that matches your usual week: sedentary multiplies BMR by 1.2, light by 1.375, moderate by 1.55, active by 1.725 and very active by 1.9. The multiplier applied is shown with the result, so you can check it.

How do I use the result to lose or gain weight?

Start from TDEE, not BMR: eat below it to create a deficit or above it for a surplus. BMR only covers complete rest, so cutting from that figure would set a target lower than you intended.

Related tools

For developers — API access

Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.

API endpoint

POSThttps://api.kit.forhosting.com/dev/calorie-needs

Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.

Call it from your stack

curl -X POST https://api.kit.forhosting.com/dev/calorie-needs \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"sex":"male","weight_kg":80,"height_cm":180,"age_years":30,"activity":"sedentary"}'

const res = await fetch("https://api.kit.forhosting.com/dev/calorie-needs", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "sex": "male",
    "weight_kg": 80,
    "height_cm": 180,
    "age_years": 30,
    "activity": "sedentary"
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/dev/calorie-needs",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "sex": "male",
    "weight_kg": 80,
    "height_cm": 180,
    "age_years": 30,
    "activity": "sedentary"
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/dev/calorie-needs", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"sex":"male","weight_kg":80,"height_cm":180,"age_years":30,"activity":"sedentary"}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"sex":"male","weight_kg":80,"height_cm":180,"age_years":30,"activity":"sedentary"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/dev/calorie-needs", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "sex": "male",
  "weight_kg": 80,
  "height_cm": 180,
  "age_years": 30,
  "activity": "sedentary"
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "dev.calorie_needs",
  "status": "queued",
  "_links": {
    "result": "/tasks/tsk_…/result"
  }
}

The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.

Pricing

Per request$0.002

Published price — no tokens, no invented credits. A failed task is never charged.

Errors

HTTP	Code	Meaning
`401`	`unauthorized`	Missing or invalid API key.
`402`	`insufficient_balance`	Your balance doesn't cover the task price.
`404`	`unknown_type`	That task type doesn't exist.
`429`	`rate_limited`	Too many requests. Use the webhook instead of polling.

Technical notes

The Mifflin-St Jeor equation

The worked example — male, 80 kg, 180 cm, 30 years, sedentary — yields a BMR of 1780 and a TDEE of 2136 kcal. dev.calorie_needs first computes basal metabolic rate (BMR) with the Mifflin-St Jeor formula: 10 times weight_kg plus 6.25 times height_cm minus 5 times age_years, then plus 5 for male or minus 161 for female. That resting figure is multiplied by an activity_factor to give total daily energy expenditure (tdee), the calories needed to maintain weight at the stated activity. The five recognised levels map to fixed multipliers: sedentary 1.2, light 1.375, moderate 1.55, active 1.725 and very_active 1.9. The response returns every input alongside activity_factor, bmr and tdee, so the multiplier that was applied is explicit and the two calorie figures can be reconciled by hand.

Required fields, ranges and rounding

All of sex, weight_kg, height_cm, age_years and activity are required. sex must be male or female, and activity must be one of the five enum values; any other string returns a typed invalid_input error. weight_kg must be a finite number in the range greater than 0 up to 500, height_cm greater than 0 up to 300, and age_years greater than 0 up to 120, which fences off impossible bodies before arithmetic runs. decimals is an integer from 0 to 2 (default 0) and controls rounding of both bmr and tdee.

Integration use cases

Onboarding calculators

Embed the widget so new members see their BMR and TDEE instantly from sex, weight, height, age and activity.

Batch meal-plan sizing

Call the API across a roster to size portions and macros from each person's tdee in a single run.

Technical questions

Which equation is used for BMR?

Mifflin-St Jeor: 10*weight_kg + 6.25*height_cm - 5*age_years, plus 5 for male or minus 161 for female.

How is TDEE derived from BMR?

BMR is multiplied by the activity_factor for your level: sedentary 1.2, light 1.375, moderate 1.55, active 1.725 or very_active 1.9.

What units and ranges are expected?

weight_kg up to 500, height_cm up to 300 and age_years up to 120, all greater than zero; out-of-range values return invalid_input.

Read the full KIT documentation →

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