VoltraHow many calories do you need a day?
Work out your resting burn from your weight, height, age and sex with the Mifflin-St Jeor equation [1], multiply it by how active you are, then take off about 500 kcal a day to lose weight.
For example, a 30-year-old man who weighs 80 kg, is 175 cm tall and is moderately active uses about 2,710 kcal a day, so about 2,210 kcal to lose weight. A 30-year-old woman who weighs 65 kg and is 162 cm uses about 2,090, or about 1,590 to lose weight (calculated).
Want the maths done for you? The calorie calculator runs these same steps with your numbers.
Step 1: your resting burn
This is what your body uses at rest in a day. The Mifflin-St Jeor equation estimates it from four things [1]:
- Men: 10 × weight in kg + 6.25 × height in cm − 5 × age + 5
- Women: 10 × weight in kg + 6.25 × height in cm − 5 × age − 161
It was built from 498 people aged 19 to 78, whose resting burn was measured in a lab [1]. A review of the equations in common use found it the most reliable: it came within 10% of the measured value for more people than any other [2]. The same review notes that most of the people it was tested on lived in the US, so treat the result as a starting point, not a measurement [2].
For the man in the example: 10 × 80 + 6.25 × 175 − 5 × 30 + 5 = about 1,750 kcal. For the woman: about 1,350 kcal.
Step 2: how active you are
Multiply your resting burn by the factor for your activity level. These are the levels and factors Voltra uses. They include your training, so you don't add workouts on top.
| Activity level | Factor | Man, 80 kg | Woman, 65 kg |
|---|---|---|---|
| Sedentary Desk job, almost no walking. Training included. | 1.2 | 2,100 | 1,620 |
| Lightly active Light walking + 1–3 short workouts/week. | 1.375 | 2,400 | 1,860 |
| Moderately active Some walking + 3–5 workouts/week. Most lifters. | 1.55 | 2,710 | 2,090 |
| Very active Active job or athlete, 6+ hard sessions/week. | 1.725 | 3,020 | 2,330 |
| Extra active Manual labour or 2-a-day training. | 1.9 | 3,320 | 2,570 |
Calories a day to stay the same weight, for the two examples (both 30 years old; the man 175 cm, the woman 162 cm). Calculated with the equation [1] and rounded to 10.
Step 3: losing or gaining
- To lose weight, Voltra takes 250, 500 or 1,000 kcal a day off, and shows them as about a quarter, a half and one kilo a week. 500 is where it starts.
- To gain, it adds 250 or 500 kcal a day.
Those weekly figures are rough. Weight changes more slowly than simple arithmetic suggests, because your body adapts as it changes: in one model, the response to a lasting change in what you eat has a half-time of about a year [3]. That's why the numbers are worked out again as your weight changes: when you log today's weight, Voltra updates your weight to the average of the last 7 days and recalculates your target from it.
Never below 1,200
Voltra never recommends less than 1,200 kcal a day. For a 60-year-old woman who weighs 50 kg and is 150 cm tall, the sum comes to about 1,010 kcal to lose weight, so Voltra sets 1,200 instead. You can type a lower target yourself; if it's below your resting burn, Voltra warns you once, and keeps your number.
What the Gulf guides say
Bahrain's official dietary guide lists daily calories by age and sex, as ranges that depend on how active you are [4]:
| Age | Women | Men |
|---|---|---|
| 19 to 30 | 1,800–2,400 | 2,400–3,000 |
| 31 to 59 | 1,600–2,200 | 2,200–3,000 |
| Pregnant or breastfeeding | 1,800–2,800 | – |
Saudi Arabia's Healthy Food Palm gives the energy in each nutrient: about 9 kcal per gram of fat, and about 4 per gram of carbohydrate or protein [5]. Our comparison of the Gulf's food guides has the rest of their advice.
How Voltra sets yours
- During setup, you give your sex, age, height, weight and goal. Voltra assumes you're moderately active until you say otherwise.
- On the Eat tab, tap Adjust budget to see the recommendation and why. From there you can change your goal or activity, or set your own target.
- Log your weight now and then. The target follows your 7-day average.
Frequently asked
How many calories should I eat to lose weight?
Voltra's usual starting point is 500 kcal a day less than you use. For a moderately active 30-year-old man who weighs 80 kg and is 175 cm tall, that's about 2,210 kcal a day.
Do I eat back the calories from my workouts?
Not in Voltra. Your activity level already includes your training, so adding workouts on top would count them twice.
Is 1,200 calories a day too little?
Voltra never recommends less than 1,200 kcal a day. Going lower is something to decide with a doctor.
Why am I losing weight more slowly than the app says?
The weekly figures are estimates. Your body adapts as your weight changes, so weight comes off more slowly over time. Keep logging your weight: the target is recalculated from your 7-day average.
Sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition 51(2):241–247
- Frankenfield D, Roth-Yousey L, Compher C (2005). Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association 105(5):775–789
- Hall KD, Sacks G, Chandramohan D, et al. (2011). Quantification of the effect of energy imbalance on bodyweight. The Lancet 378(9793):826–837
- وزارة الصحة، مملكة البحرين (٢٠٢٣). الدليل الإرشادي الغذائي لمملكة البحرين. In Arabic. Table 3, printed pp. 34–35.
- وزارة الصحة، المملكة العربية السعودية، الإدارة العامة للتغذية (٢٠١٢). الدليل الغذائي السعودي: النخلة الغذائية الصحية. In Arabic. Message 5, p. 21.
Sources checked on 30 September 2026. The activity levels, the paces and the 1,200 kcal floor are Voltra's own settings, as of version 2.1.1.
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