Calculators explained

The numbers, and what they actually mean

Top 1% Fit works out your calorie and training targets from standard, published formulas. Here is every one of them, in the open — including what each one cannot tell you.

BMR — Basal Metabolic Rate

Formula

Men: (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
Women: (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161

What it is

The energy your body uses at complete rest, just to keep your organs running. It is the floor of your daily calorie needs, not a target to eat at.

How this app uses it

Top 1% Fit uses the Mifflin-St Jeor equation, one of the most widely used formulas for estimating resting energy expenditure.

What it cannot tell you

This is a population-based estimate. Individual metabolic rate varies with body composition, hormones and other factors it cannot see.

TDEE — Total Daily Energy Expenditure

Formula

TDEE = BMR × activity factor (1.25 sedentary → 1.72 very active)

What it is

An estimate of everything you burn in a day, including walking, training and daily movement. It is the number your calorie target is built from.

How this app uses it

The activity multiplier is chosen from how you describe a typical week. Your calorie target is then adjusted from TDEE by your goal and current training phase.

What it cannot tell you

Activity multipliers are broad bands. If your weight is not moving as expected after two or three weeks, the multiplier is usually the thing to revisit.

BMI — Body Mass Index

Formula

BMI = weight kg ÷ (height m)²

What it is

A ratio of weight to height, used as a rough population-level screening figure. Under 18.5 is classed as underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30+ obese.

How this app uses it

Calculated directly from the height and weight in your profile.

What it cannot tell you

BMI cannot distinguish muscle from fat. A muscular person can read as "overweight" while carrying very little body fat. Treat waist measurement and progress photos as better signals.

Macros — protein, carbohydrate and fat

Formula

Protein: 1.9–2.2 g per kg body weight (varies by goal)
Fat: ~0.85 g per kg body weight
Carbohydrate: whatever calories remain

What it is

How your daily calories are split across the three macronutrients. Protein is set first because it is the one that most affects whether you keep muscle.

How this app uses it

Protein and fat are set from body weight, then carbohydrate fills the remaining calories. Protein provides 4 kcal per gram, carbohydrate 4, fat 9.

What it cannot tell you

These are starting points, not precise requirements. Consistency across a week matters far more than hitting an exact number on any single day.

1RM — estimated one-rep max

Formula

Estimated 1RM = weight × (1 + reps ÷ 30)

What it is

An estimate of the heaviest single rep you could perform, worked out from a set you already completed — without having to attempt a true maximum.

How this app uses it

Top 1% Fit uses the Epley formula and records your best estimate per exercise automatically as you log sets.

What it cannot tell you

Accuracy drops as rep count rises; estimates from sets above roughly 10 reps become unreliable. It is a progress marker, not a number to train to.

Body fat estimate

Formula

Deurenberg: (1.20 × BMI) + (0.23 × age) − (10.8 × sex) − 5.4

What it is

A rough indication of body fat percentage derived from BMI, age and sex.

How this app uses it

Calculated from your profile using the Deurenberg equation, and labelled as an estimate everywhere it appears in the app.

What it cannot tell you

This is the least precise figure in the app. Because it is derived from BMI, it inherits the same blindness to muscle mass. Use the direction it moves over time, never the absolute number.

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