About Ethereal
Ethereal is a free set of weight-loss calculators and guides built on one principle: give people the right number, explain where it came from, and never get in the way.
Why it exists
Most calorie calculators are the top of a sales funnel. They give you a number, hide the reasoning and ask for your email. We wanted the opposite: a fast, private, honest toolkit that a dietitian would be comfortable recommending.
Methodology
| Tool | Method | Notes |
|---|---|---|
| Calories | Mifflin-St Jeor (default), revised Harris-Benedict, Katch-McArdle; standard 1.2–1.9 activity multipliers | Deficits capped at 25% of TDEE (550 kcal always allowed); floors of 1,200 (women) and 1,500 kcal (men) |
| Timeline | Weekly simulation recomputing TDEE from projected weight; 7,700 kcal per kg | Does not model adaptive thermogenesis; real timelines run 10–20% longer |
| Macros | 4/4/9 kcal per gram; 14 g fibre per 1,000 kcal | Protein-first mode fixes protein in g/kg and fat as % of calories |
| BMI | WHO adult categories; ponderal index | Lower risk thresholds apply for some ethnic groups |
| Body fat | U.S. Navy circumference method (Hodgdon & Beckett); ACE categories | ±3–4% versus DEXA |
| Protein | Ranges from recent meta-analyses: 1.6–2.2 g/kg training, 1.6–2.4 g/kg in a deficit, ≥1.2 g/kg over 65 | Lean-adjusted mass above 30% body fat |
| Ideal weight | Devine, Robinson, Miller, Hamwi; BMI 18.5–24.9 range | Reference points only |
| Food diary | Built-in database of 1,400+ halal-friendly foods (no pork, gelatin or alcohol): generic items aligned with USDA FoodData Central and McCance & Widdowson, world-cuisine dishes, and branded and chain items from published labels; plus Open Food Facts for packaged products and barcodes, queried directly from your browser | Energy 4/4/9 kcal per gram; per-100 g storage so portions stay editable; every row checked by a validator (unique ids, plausible values, Atwater energy within 12%) |
| Recipes and day planner | 66 recipes assembled from database rows, so totals are the ingredient sums; the day planner searches every breakfast–lunch–dinner–snack combination for the one closest to your calorie target with protein covered | Meals carry 25 g+ protein, snacks 10 g+; over-shooting calories is penalised more than under |
| Exercise | Compendium of Physical Activities MET values; kcal = MET × 3.5 × kg ÷ 200 per minute | Not added to the target unless you opt in, because MET and watch estimates run high |
| Two-week check | Exponentially-smoothed trend (α 0.1), 14-day regression slope compared with the planned rate in a toward-the-goal frame, so loss, gain and maintenance all get advice in the right direction; adjustment capped at ±250 kcal, floors respected | Waits for 14 days of data before recommending anything |
| Water | 35 ml/kg baseline + 12 ml per minute of exercise + climate and pregnancy allowances | Drinking-water guidance; food supplies ~20% more |
How it is built
The site is a static build with no server, no database and no third-party scripts. Calculators are small islands of JavaScript that run entirely in your browser. Your profile is stored in your browser's local storage so you type it once; clearing site data removes it completely. The code is open and every calculation has automated tests.
Limits
Every equation is a population average with roughly ±10% error for an individual. The tools are educational and are not a substitute for a clinician, especially if you are under 18, pregnant, have a medical condition, or have a history of disordered eating. Read the full disclaimer.