TDEE for Bulking — Women Age 18-24, Sedentary

Bulking means eating above your total daily energy expenditure (TDEE) on purpose, so the extra energy — combined with resistance training — supports muscle gain. The surplus on this page is a modest 300 kcal a day, the lean-bulking approach that prioritises muscle over fat gain. For a 18 to 24-year-old woman who is sedentary — a desk job, very little walking and no planned exercise — the classic office-worker pattern of sitting most of the day and moving mainly between rooms, the car and the sofa — the worked example below uses a body weight of 65 kg (143 lb) and a height of 165 cm, and gives a lean-bulking target of 1,998 kcal/day — TDEE plus a 300 kcal surplus. That figure is an estimate built from a published formula, not a personal prescription: your own numbers will differ if your weight, height or daily activity differ from the example.

The worked example is the whole point of this page. Rather than quoting a single number with no working, it shows the Mifflin-St Jeor equation step by step, multiplies the result by the activity factor for a sedentary lifestyle, and then turns the total into a daily calorie target for bulking. Use the same steps with your own measurements, or use the calculator linked below, and you will get a target matched to you rather than to the example person.

Calculate your own TDEE

Your weight, height, age and activity level are almost certainly different from the example above, so run your own numbers with the TDEE calculator. It uses the same Mifflin-St Jeor equation and the same activity multipliers shown on this page, and it also gives cutting, maintenance and bulking targets from a single set of inputs. If you only want the resting figure, the BMR calculator gives that on its own. For the bulking figure specifically, try the Bulk calorie calculator.

Related pages and tools:

The formula: Mifflin-St Jeor (1990)

The Mifflin-St Jeor equation is the most widely validated formula for estimating resting energy expenditure in adults. It was published by Mifflin et al. in the American Journal of Clinical Nutrition in 1990 (Mifflin MD et al., Am J Clin Nutr 1990;51(2):241–247), and it is the equation most calculators and many clinical settings use as a starting point. For women it is:

BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161

For men the final term is + 5 instead of − 161. TDEE is then the BMR multiplied by an activity factor: 1.2 for sedentary, 1.375 for lightly active, 1.55 for moderately active, 1.725 for very active and 1.9 for extremely active. These multipliers are the standard values used with the Mifflin-St Jeor equation.

Working through the example for a 18 to 24-year-old woman at 65 kg and 165 cm:

  • 10 × 65 kg = 650 kcal
  • 6.25 × 165 cm = 1,031.25 kcal
  • 5 × 21 years = 105 kcal
  • Constant: − 161 kcal

So BMR = 650 + 1,031.25 − 105 − 161 = 1,415 kcal/day. That is the energy the body would use at complete rest, before any movement, digestion or exercise is counted. Multiplying by the sedentary factor of 1.2 gives TDEE = 1,415 × 1.2 = 1,698 kcal/day.

Your targets at a glance

Figure Value
BMR (Mifflin-St Jeor) 1,415 kcal/day
Activity level Sedentary (×1.2)
TDEE 1,698 kcal/day
Cutting target (TDEE − 500) 1,200 kcal/day (held at safety floor)
Maintenance target 1,698 kcal/day
Lean-bulk target (TDEE + 300) 1,998 kcal/day
Larger-bulk target (TDEE + 500) 2,198 kcal/day
Safety floor 1,200 kcal/day (women)

Bulking is the target this page is built around — 1,998 kcal a day, TDEE plus 300 kcal. The other rows are there so you can see how the three goals relate: a 500 kcal daily deficit is worth roughly 0.5 kg of fat loss a week (about 3,500 kcal per week per 0.45 kg), while a 300 kcal surplus is worth roughly 0.25 kg of gain a week. Note the cutting row: TDEE minus 500 kcal would be 1,198 kcal, which is below the 1,200 kcal/day safety floor for women, so the cutting target is held at the floor of 1,200 kcal/day and should only go lower under medical supervision.

How activity level changes the number

The same 18 to 24-year-old woman at 65 kg and 165 cm has the same BMR of 1,415 kcal/day whatever the lifestyle — but TDEE moves a lot with activity:

Activity level Multiplier TDEE
Sedentary 1.2 1,698
Lightly Active 1.375 1,946
Moderately Active 1.55 2,193
Very Active 1.725 2,441
Extremely Active 1.9 2,688

The gap between sedentary and extremely active is 990 kcal a day for this person, which is why two people of the same age, sex, weight and height can need very different calorie intakes. It is also why activity level is the input people most often get wrong: be honest about a typical week, not your best week. If you sit most of the day and train three times a week, you are closer to lightly active than moderately active, and using the higher factor inflates the target. The sedentary factor of 1.2 used on this page describes a desk job, very little walking and no planned exercise — the classic office-worker pattern of sitting most of the day and moving mainly between rooms, the car and the sofa — if that does not describe your week, use the row in the table that does.

What this number does not tell you

A TDEE estimate is a starting point, not a measurement. The Mifflin-St Jeor equation was validated on population averages, and individual resting metabolic rate varies by roughly ±10% around the prediction because of differences in muscle mass, genetics and health. Two people with identical age, sex, weight and height can have BMRs a few hundred calories apart. The equation also uses total body weight, so it is less accurate for very muscular people (it underestimates) and for people with a high body-fat percentage (it overestimates), because muscle burns more energy at rest than fat does.

Activity multipliers are blunt by design. They compress a whole week of movement, training, work and fidgeting into a single number, and they cannot capture a week that mixes desk days with long hikes, or a job that is physical some days and sedentary on others. Food intake itself also costs energy to digest — the thermic effect of food, roughly 10% of intake — which the multiplier approach folds in approximately rather than measuring. Treat the 1,998 kcal target as a hypothesis: follow it for two to three weeks, watch the weekly weight average, and adjust by 100–200 kcal based on what actually happens.

Age 18-24: what changes at this stage

At 18 to 24, resting metabolic rate is at its lifetime peak for most people. Muscle mass is still being built, recovery from training is fast, and daily activity is often high — walking to lectures or work, playing sport, socialising on foot. The catch is inconsistency: exam periods, shift work and irregular meals can swing intake and activity by hundreds of calories from week to week, so a single day of tracking says very little. The figure on this page is a starting point for a typical week, not a verdict on any one day.

Energy needs at this age are driven more by activity than by age itself. Two 21-year-olds of the same weight can differ by 600 kcal a day purely because one cycles everywhere and the other drives. If you are a student or in your first job, track a normal week — including weekends — before deciding your target is wrong.

How to use the 1,998 kcal bulking target

Start at 1,998 kcal a day — TDEE plus 300 kcal — and hold it for three to four weeks before changing anything. A 300 kcal daily surplus adds up to about 2,100 kcal a week, which should show up as roughly 0.25 kg of weight gain a week once water and glycogen settle. That is the intended rate for a lean bulk: faster than that and a growing share of the gain is fat; slower and you are barely above maintenance. Weigh yourself three to four times a week, first thing in the morning, and compare weekly averages — daily weight moves by a kilogram or more with water, glycogen and food volume.

The surplus only builds muscle if training gives it somewhere to go. Two to four resistance sessions a week, progressing the weight or reps over time, is the minimum that makes a bulk worthwhile; without it, the extra 300 kcal a day mostly becomes fat. Protein of roughly 1.6–2.2 g per kilogram of body weight a day — about 104–143 g a day for the 65 kg example — supplies the raw material for that muscle, spread across three to five meals so each meal delivers 25–40 g.

If weight is not moving after three weeks, add another 100–200 kcal a day, preferably from carbohydrate around training, and reassess. If weight is climbing faster than about 0.5 kg a week, trim 100–150 kcal a day — the goal is muscle, not a fast scale. A bulk of eight to sixteen weeks followed by a return to maintenance, or a short cut, is the usual rhythm. And remember the floor works the other way too: the cutting target in the table above is 1,200 kcal a day — held at the 1,200 kcal safety floor rather than the full 500 kcal deficit, because the raw figure would fall below it, which is why a deficit should never be set by subtracting a fixed number without checking the floor.

Frequently asked questions

What is the TDEE for a 18 to 24-year-old woman who is sedentary?

For the worked example on this page — 65 kg, 165 cm, age 21 — BMR is 1,415 kcal/day by Mifflin-St Jeor and TDEE is 1,698 kcal/day at the sedentary multiplier of 1.2. Your own TDEE will differ if your weight, height or activity differ; use the TDEE calculator with your own measurements.

How was the 1,998 kcal bulking target calculated?

It starts from TDEE of 1,698 kcal/day, plus a 300 kcal daily surplus for a lean bulk. A larger 500 kcal surplus would give 2,198 kcal a day, but more surplus means more of the gain is fat. The target is an estimate, not a prescription.

Does TDEE fall as you get older?

Yes, slowly. In the Mifflin-St Jeor equation the age term subtracts 5 kcal a day for every year of age, so BMR falls by about 50 kcal a decade when weight and height stay the same — and in practice it often falls faster because muscle mass and daily activity tend to decline with age. That is one reason strength training matters more, not less, as the decades pass. For this page's example, moving from age 21 to ten years older at the same weight and height would lower BMR by 50 kcal a day, to 1,365 kcal/day.

Should I use my current weight or my goal weight in the formula?

Use your current weight. TDEE describes what your body uses now; plugging in a goal weight answers a different question — what you will need once you get there. Recalculate every 5 kg of weight change or so, because a lighter body burns fewer calories and a target set at your old weight gradually becomes a surplus. For a 18 to 24-year-old woman, a 5 kg change moves BMR by 50 kcal a day, which is enough to matter over months.

Why is my TDEE different from another calculator's?

Different calculators use different equations (Mifflin-St Jeor, Harris-Benedict, Katch-McArdle) and different activity definitions, so results commonly differ by 100–300 kcal. That spread is normal and is another reason to treat any single figure as a starting estimate and adjust from two to three weeks of real weight data. The figure on this page, 1,698 kcal/day, comes from Mifflin-St Jeor (Mifflin et al., 1990) with the standard activity multipliers — check which equation another calculator used before assuming one of them is wrong.

How fast should I gain weight on 1,998 kcal a day?

About 0.25 kg a week is the intended rate — 300 kcal a day is roughly 2,100 kcal a week, and about 7,700 kcal stores roughly 1 kg of body tissue. If you are gaining much faster than 0.5 kg a week, trim 100–150 kcal a day; if the scale is flat after three weeks, add 100–200 kcal. Never drop below 1,200 kcal a day without medical supervision.

Estimates only, not medical advice. Minimum safe intakes: 1,200 kcal/day women, 1,500 kcal/day men — consult a healthcare professional before a very-low-calorie diet.