What health calculators does Texterfly offer?

Texterfly offers 3 free health calculators: a BMI Calculator (adult and child/teen modes, visual gauge, healthy weight range), a Calorie & Macro Calculator (Mifflin-St Jeor and Katch-McArdle formulas, macronutrient breakdown, goal-based timeline), and a Pregnancy Due Date Calculator (last menstrual period or conception date methods, trimester guide, weekly development milestones). All are for informational purposes only.

What do the BMI categories mean?

BMI (Body Mass Index) categories for adults are: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), Obese Class I (30–34.9), Obese Class II (35–39.9), and Obese Class III (40 and above). Note that BMI has significant limitations — it does not account for muscle mass, bone density, age, sex, or ethnicity. Athletes may have a high BMI due to muscle, not fat. Always consult a healthcare professional for a full health assessment.

What is the Mifflin-St Jeor formula?

The Mifflin-St Jeor formula estimates Basal Metabolic Rate (BMR) — calories burned at rest. For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161. Multiplying BMR by an activity factor gives TDEE (Total Daily Energy Expenditure), which is the estimated number of calories needed to maintain current weight.

TDEE (Total Daily Energy Expenditure) is the estimated total number of calories you burn per day, including physical activity. It is calculated by multiplying your BMR (Basal Metabolic Rate) by an activity factor: Sedentary (×1.2), Lightly active (×1.375), Moderately active (×1.55), Very active (×1.725), Extra active (×1.9). To lose weight, eat fewer calories than your TDEE; to gain, eat more.

How is a pregnancy due date calculated?

The most common method is Naegele's rule: add 280 days (40 weeks) to the first day of your Last Menstrual Period (LMP). For example, if your LMP was January 1, the estimated due date is October 8. Alternatively, add 266 days to a known conception date. Only about 5% of babies are born on their exact due date — it's an estimate within a 2-week window.

What are the pregnancy trimesters?

First Trimester: Weeks 1–12 (months 1–3). Key developments: fertilisation, heart formation, organ development. Second Trimester: Weeks 13–26 (months 4–6). Key developments: movement felt, sex identifiable, rapid growth. Third Trimester: Weeks 27–40+ (months 7–9+). Key developments: lungs mature, weight gain, preparation for birth.

Are these calculators a substitute for medical advice?

No. These calculators are for informational and educational purposes only. They are not designed to diagnose, treat, cure, or prevent any medical condition. BMI, calorie needs, and pregnancy timelines are estimates based on statistical formulas — individual health varies significantly. Always consult a qualified healthcare professional, doctor, or registered dietitian for personalised medical guidance.

How accurate is the BMI calculator?

The BMI formula is mathematically accurate — it correctly calculates weight (kg) divided by height (m²). However, BMI as a health metric has well-documented limitations: it does not distinguish between fat and muscle, does not account for where fat is stored (visceral vs subcutaneous), and may misclassify athletes as overweight and elderly people with muscle loss as normal weight. Use BMI as one data point, not a definitive measure of health.

Are these health calculators free?

Yes. All 3 health calculators are 100% free with no registration, subscription, or payment required.

Is my health data private?

Yes. All calculations run entirely in your browser. Your weight, height, age, activity level, and other personal health data are never sent to any server or stored anywhere.

What's the difference between this and a calorie calculator?

A calorie calculator gives a single daily calorie target. This tool uses the same underlying TDEE math, then breaks that target down into specific protein, carb, and fat gram targets based on your goal and diet style.

Why do carb targets change so much between diet styles?

Carbs are calculated as whatever calories remain after protein and fat are covered, so a higher fat percentage leaves far fewer calories available for carbs.

Back to Health & Fitness Calculators

Macro Calculator

Calculate daily protein/carb/fat targets based on your goal — cut, maintain, or bulk — with balanced, high protein, low carb, or keto splits. Free, no sign-up.

This uses the same TDEE math as our Calorie Calculator

Just want a calorie target without the macro split?

Calorie Calculator

Your Stats

Sex

Age

Height

ftin

Weight

lbs

Activity Level

Goal

Diet Style

Daily Calorie Target (Maintain)

2,764 kcal

Maintenance (TDEE): 2,764 kcal · BMR: 1,784 kcal

Macro Split

Protein

147g

21% of calories

Carbs

337g

49% of calories

Fat

92g

30% of calories

Per-Meal Breakdown

Meals/day

Per Meal	Calories	Protein	Carbs	Fat
1 of 3	921	49g	112g	31g

Assumes macros are spread evenly across all meals.

This calculator uses the Mifflin-St Jeor equation and standard macro-split conventions for a general estimate — it isn't personalized medical or nutrition advice. Consult a doctor or registered dietitian before starting a new diet, especially if you're pregnant, nursing, or managing a health condition.

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Free Macro Calculator — Protein, Carbs & Fat for Cutting, Maintaining, or Bulking

Calorie targets only tell half the story — what those calories are made of matters just as much for body composition, performance, and how full you feel. This calculator starts with the same BMR and TDEE math as our Calorie Calculator, then splits your daily calories into protein, carb, and fat targets based on your goal and preferred diet style — whether that's a balanced split, high protein, low carb, or keto. Everything runs instantly in plain JavaScript, no sign-up needed.

How Your Macros Are Calculated

Your calorie target comes from the Mifflin-St Jeor equation for basal metabolic rate (BMR), multiplied by an activity factor to get your total daily energy expenditure (TDEE), then adjusted up or down for your goal. From there, protein is set relative to your body weight — since protein needs scale with lean mass, not total calories — and fat is set as a percentage of your calorie target. Whatever calories remain after protein and fat are covered become your carbohydrate target.

🥩 Protein scales with body weight

Protein targets are set in grams per kilogram of body weight, which stays consistent whether you're cutting, maintaining, or bulking.

🍞 Carbs fill the remainder

Once protein and fat are covered, whatever calories are left become your carb budget — this is why carb targets shift the most between diet styles.

Tips for Hitting Your Macros

🎯

Prioritize protein first

Protein is the macro most linked to muscle retention and satiety. Hit your protein target consistently before worrying about the exact carb/fat split.

📅

Think in weekly averages

You don't need to hit your numbers exactly every single day — being close across a week matters more than perfection on any one day.

⚖️

Re-calculate as your weight changes

Both calorie needs and protein targets shift as your body weight changes, especially during a cut or bulk. Re-run the calculator every few weeks.

🍽️

Use the per-meal breakdown as a guide

Splitting your targets evenly across meals is a simple starting point — adjust based on your schedule, training times, and appetite.

🧪

Give any new split 2–3 weeks before judging it

Weight and energy levels fluctuate day to day. Give a new calorie or macro target a few weeks before deciding whether to adjust it.

Frequently Asked Questions

What's the difference between this and your Calorie Calculator?

The Calorie Calculator gives you a single daily calorie target. This tool uses the same underlying TDEE math, then breaks that calorie target down into specific protein, carb, and fat gram targets based on your goal and diet style.

How is my protein target calculated?

Protein is set in grams per kilogram of body weight (roughly 1.6–2.2 g/kg depending on your chosen diet style), which is the standard approach used in most evidence-based nutrition guidance for muscle retention and growth.

Which diet style should I pick?

Balanced works well for most people. High Protein suits those prioritizing muscle retention during a cut. Low Carb and Keto are stricter approaches some people prefer for appetite control or personal preference — none is inherently "better" for fat loss than the others at matched calories and protein.

Why do my carbs change so much between diet styles?

Because carbs are calculated as whatever calories remain after protein and fat are covered. A higher fat percentage (like Keto) leaves far fewer calories for carbs than a Balanced split does.

Is this calculator accurate for everyone?

It gives a solid starting estimate based on established formulas, but individual metabolism, medical conditions, and activity patterns vary. Treat the result as a starting point to adjust from, not a fixed prescription — and check with a doctor or dietitian for personalized guidance.

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