Berechne BMI, TDEE, Kalorien, Makros und mehr — 100% kostenlos, privat und sofort.
Every key fitness metric — one tool, zero friction
BMI-Rechner
Berechne deinen Body-Mass-Index und finde deinen gesunden Gewichtsbereich.
TDEE-Rechner
Berechne deinen Gesamtenergieverbrauch basierend auf deiner Aktivität.
Grundumsatz-Rechner
Finde deinen Grundumsatz — Kalorien im Ruhezustand verbrannt.
Körperfett-Rechner
Schätze deinen Körperfettanteil mit mehreren Methoden.
Idealgewicht-Rechner
Finde dein Idealgewicht basierend auf Größe und Körperbau.
Kalorienrechner
Erhalte dein tägliches Kalorienziel zum Abnehmen, Halten oder Zunehmen.
Makro-Rechner
Berechne optimale Protein-, Kohlenhydrat- und Fettverhältnisse.
Wasseraufnahme-Rechner
Berechne deinen täglichen Wasserbedarf nach Gewicht und Aktivität.
Herzfrequenz-Rechner
Finde deine Trainingsherzfrequenzzonen für optimales Cardio.
Magermasse-Rechner
Berechne deine fettfreie Körpermasse.
1RM-Rechner
Schätze dein Maximalgewicht für jede Übung.
Protein-Rechner
Finde deine tägliche Proteinzufuhr für Muskelaufbau und Erholung.
Schlafrechner
Finde optimale Schlaf- und Aufwachzeiten nach Schlafzyklen.
Schlafschuld-Rechner
Berechne deine angesammelte Schlafschuld und Erholungsplan.
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Why CalaiFitness
Every calculation runs entirely in your browser using JavaScript. No data is ever sent to our servers, logged, or sold. What you enter stays on your device — always.
0 bytes
sent to servers
We use only peer-reviewed formulas: Mifflin-St Jeor for BMR/TDEE, the US Navy method for body fat, WHO BMI standards, and the Karvonen formula for heart rate zones.
10+
validated formulas
Your results are saved automatically to your browser's local storage. Open the dashboard to see your history and track how your numbers change week over week.
100%
on-device storage
Simple by Design
Pick from 18 free calculators covering every key fitness metric — from BMI to body fat to daily calories.
Input your measurements in metric or imperial units. Our clean, distraction-free interface takes seconds to fill out.
Results appear immediately, with context, categories, and advice. Save to history to track your progress over time.
Quick Answers
TDEE (Total Daily Energy Expenditure) is the total calories your body burns each day, including activity. It's the most important number in nutrition — knowing it lets you set an exact calorie target for fat loss, maintenance, or muscle gain.
Learn more →BMI is accurate as a population-level screening tool for adults. It has known limitations for athletes and older adults due to muscle mass differences. For a complete picture, pair it with body fat percentage.
Learn more →Completely private. All calculations run in your browser — nothing is ever sent to our servers. We have no database of user data. Your history is stored in your browser's localStorage only.
Learn more →Science-Based Articles
What is a healthy BMI for a 45-year-old woman who exercises? Discover why standard BMI charts mislead active women, ideal body fat ranges, and how to assess true health.
Read article →How many calories does a 5'6 woman need to maintain weight? Complete calorie chart by age, weight, and activity level with exact macro formulas.
Read article →Need 150 to 160 grams of protein daily? Here is how to hit your protein target easily with whole foods, budget-friendly staples, and exact meal breakdowns.
Read article →No sign-up. Results in under 30 seconds. Your calculator entries stay on your device.
