Calorie deficit calculator
Losing 5 kg in 70 days on 2500 kcal of maintenance means a 550 kcal daily deficit and an intake of about 1950 kcal. The goal is spread evenly at 7700 kcal per kilogram, or 3500 per pound. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Target weight to lose
- 5
- Plan length in days
- 70
- Daily maintenance energy
- 2,500
- Weight unit
- Kg
- Kcal per unit
- 7,700
- Total deficit kcal
- 38,500
- Daily deficit kcal
- 550
This calorie deficit calculator converts a target weight loss, a planning timeframe in days, and your daily maintenance calories into the average daily calorie deficit and the daily calorie intake that would produce that deficit. The model is the classic energy-balance approximation used in coaching worksheets and consumer apps: about 7700 kilocalories per kilogram of body tissue, or 3500 kilocalories per pound, spread evenly across the days you choose. For example, losing five kilograms over seventy days at a twenty-five-hundred-calorie maintenance level implies a total deficit of thirty-eight thousand five hundred kilocalories, a daily deficit of five hundred fifty, and a daily intake near one thousand nine hundred fifty. The engine is fully deterministic finite arithmetic with no network calls, no sampling, and no date-dependent shortcuts.
What a calorie deficit plan returns and what the numbers mean
A calorie deficit is the gap between the energy you expend on a typical day and the energy you take in from food and drink. Over many days, a sustained deficit is the arithmetic core of most weight-loss plans, even though real bodies also adapt, retain water, and shift lean mass. This tool does not guess your metabolism from age or activity; you supply maintenance calories (often labeled TDEE) from a prior estimate, a wearable average, or a clinical assessment.
You also supply how much weight you want to lose and how many days you want the plan to span. The calculator multiplies the weight target by a fixed energy density, 7700 kilocalories per kilogram or 3500 per pound, to obtain a total energy debt, divides by the day count for a constant daily deficit, and subtracts that daily deficit from maintenance to yield a target intake.
Where daily deficit targets fit in coaching, products, and study
Coaches and clients use a fixed daily deficit as a starting contract before they adjust for hunger, training load, and plateaus. App builders map a goal form into intake targets for food logs without shipping opaque calculator code. Students and dietetic trainees check textbook examples that assume 3500 kilocalories per pound or 7700 per kilogram and need a fast, offline source of daily rates.
Product and education tools use the same contract when a learner types a five-kilogram goal and a ten-week window and the UI must show both the deficit and the implied intake beside a maintenance field. Extreme goals that push daily intake below safe ranges are still computed transparently so the UI can warn; this engine does not silently clamp or invent medical advice.
Pair it with body-composition or heart-rate tools when you are building a small lab of free, deterministic health helpers, and always treat the output as a planning estimate rather than a prescription.
What you can do with it
Goal-to-intake planning
Convert a kg or lb weight-loss target and a day count into a daily calorie deficit and intake from known maintenance calories.
Coaching worksheets and apps
Generate reproducible deficit and intake numbers for client plans, onboarding flows, and food-log defaults.
FAQ
What does the calorie deficit calculator cost?
It is free in your browser on this page.
What happens if the timeframe is zero or negative?
A non-positive timeframe cannot define a daily calorie deficit rate.
Does this tool estimate my maintenance calories?
No. You provide maintenance (TDEE). The calculator only turns a weight goal and day count into deficit and intake.
Why might daily intake be very low or negative?
An aggressive loss over a short timeframe can exceed maintenance. The engine reports the arithmetic so apps can warn; it does not give medical advice.
Why might my real weight loss differ from the plan?
The 7700 kcal per kilogram rule is an approximation: real bodies adapt, hold water and shift lean mass. Treat the daily deficit as a starting point and adjust it for hunger, training load and plateaus.
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
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/health/calorie-deficit \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"weight_loss":5,"timeframe_days":70,"maintenance_calories":2500}'const res = await fetch("https://api.kit.forhosting.com/health/calorie-deficit", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"weight_loss": 5,
"timeframe_days": 70,
"maintenance_calories": 2500
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/health/calorie-deficit",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"weight_loss": 5,
"timeframe_days": 70,
"maintenance_calories": 2500
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/health/calorie-deficit", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"weight_loss":5,"timeframe_days":70,"maintenance_calories":2500}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"weight_loss":5,"timeframe_days":70,"maintenance_calories":2500}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/health/calorie-deficit", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"weight_loss": 5,
"timeframe_days": 70,
"maintenance_calories": 2500
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "health.calorie_deficit",
"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
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_weight_loss | 200 |
max_timeframe_days | 3650 |
max_maintenance_kcal | 20000 |
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
What a calorie deficit plan returns and what the numbers mean
The response echoes the normalized inputs, the kcal-per-unit constant, total and weekly deficit figures, daily deficit and intake, a method tag energy_balance, a short formula string, and the decimal precision used. There is no machine-learning path and no random sampling: either the finite arithmetic succeeds inside the documented limits or the request fails with invalid_input. Rejected cases include missing weight loss, timeframe, or maintenance; non-finite values; values above the documented ceilings; non-positive weight loss or maintenance; and any timeframe that is zero or negative, because a non-positive span cannot define a meaningful daily rate. If you need BMR formulas, macro splits, or workout fueling, pair this page with those dedicated tools; this landing answers only the deficit-from-goal rewrite with stable numeric output for worksheets, product UIs, and API consumers that must not invent adaptive models.
How inputs are read, which units apply, and why results stay reproducible
Optional leading plus signs and scientific notation on numeric strings are allowed when they parse as finite decimals; embedded spaces, hex prefixes, and non-numeric tokens are rejected with a clear message so a bad cell does not become a wrong intake target. The preferred fields are weight_loss for the amount to lose, timeframe_days for the plan length, and maintenance_calories for daily maintenance energy in kilocalories. Aliases such as loss, target_loss, days, timeframe, duration_days, maintenance, tdee, and maintenance_kcal are accepted so spreadsheets, query strings, and typed forms can reuse one contract. Optional weight_unit defaults to kilograms and also accepts kg, kilogram, lb, lbs, pound, and pounds; pounds use the 3500 kilocalorie convention while kilograms use 7700. An optional precision field, with aliases decimals and dp, chooses how many decimal places to expose, defaulting to two and capped at fifteen so JSON goldens stay stable. Pair the free browser run on this page with the priced API when you need the identical mathematical result inside an automated pipeline without re-implementing the deficit formulas yourself.
Where daily deficit targets fit in coaching, products, and study
On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split — free interactive exploration and a priced, identical API — matches the rest of the KIT tier-A catalog and lets you move from a classroom demo to an automated pipeline without changing the mathematical result.
Integration use cases
Deterministic test fixtures
Seed CI and unit tests with fixed daily_deficit_kcal and daily_intake_kcal from the classic 7700/3500 model.
Technical questions
How are daily deficit and intake calculated?
total_deficit_kcal = weight_loss × 7700 (kg) or × 3500 (lb); daily_deficit_kcal = total / timeframe_days; daily_intake_kcal = maintenance_calories − daily_deficit_kcal.