IDEAL WEIGHT CALCULATOR

Four formulas are commonly used for ideal weight calculation, each developed in different decades using different population data. Here is what each one does and when it works best.

Devine Formula (1974) is the most widely used in medicine — it is actually the basis for drug dosage calculations in many clinical settings. For men: 50 + 2.3 x (height in inches - 60). For women: 45.5 + 2.3 x (height in inches - 60). Let me make this concrete. A man at 178 cm (70 inches): 50 + 2.3 x 10 = 73 kg. A woman at 165 cm (65 inches): 45.5 + 2.3 x 5 = 57 kg. Devine is clinically important but tends to give lower numbers that may feel unrealistic for muscular or larger-framed individuals.

Robinson Formula (1983) is an updated version of Devine, built from a broader population sample. For men: 52 + 1.9 x (height in inches - 60). For women: 49 + 1.7 x (height in inches - 60). Same 178 cm man: 52 + 1.9 x 10 = 71 kg. Same 165 cm woman: 49 + 1.7 x 5 = 57.5 kg. Robinson typically gives similar results to Devine but is considered slightly more representative of the general population.

Miller Formula (1983) is interesting because it produces more realistic results for taller people, where the other formulas tend to underestimate. For men: 56.2 + 1.41 x (height in inches - 60). For women: 53.1 + 1.36 x (height in inches - 60). Same man: 56.2 + 1.41 x 10 = 70.3 kg. Same woman: 53.1 + 1.36 x 5 = 59.9 kg. If you are above 180 cm, Miller probably gives you the most realistic number.

Hamwi Formula (1964) is the oldest of the four and commonly referenced in nutrition practice. For men: 48 + 2.7 x (height in inches - 60). For women: 45.5 + 2.2 x (height in inches - 60). Same man: 48 + 2.7 x 10 = 75 kg. Same woman: 45.5 + 2.2 x 5 = 56.5 kg. Hamwi tends to give the highest values of the four, which some people find more realistic.

My practical advice: average all four results. In our examples, the 178 cm man gets 73, 71, 70.3, and 75 — averaging to about 72.3 kg. The 165 cm woman gets 57, 57.5, 59.9, and 56.5 — averaging to about 57.7 kg. This averaged range is more reliable than any single formula. Our calculator displays every formula result and the overall average so you can see the full picture.

While ideal weight formulas are a decent starting point, there are specific situations where they can actively mislead you. I have seen all of these with real clients.

1. People with significant muscle mass. This is the most obvious one. If you have been lifting weights consistently for several years, you probably carry 5–10 kg more muscle than the average person your height. The formulas do not account for this. I have a client who is 175 cm, weighs 82 kg, and looks like a fitness model — but every formula says he should weigh 68–72 kg. Following that advice would mean losing muscle, not fat.

2. Different body frames. Some people genuinely have wider shoulders, thicker wrists, and denser bones than average. The formulas assume a medium frame, which means narrow-framed people might be healthy below the range while broad-framed people are healthy above it. Wrist circumference is actually a reasonable proxy for frame size — under 17 cm for men is small-framed, over 19 cm is large-framed.

3. Age-related changes. None of the four formulas account for age, but body composition changes significantly as you get older. Muscle mass naturally decreases (sarcopenia) and fat percentage tends to increase, even if weight stays the same. For adults over 60, research actually suggests that being slightly overweight (BMI 25–27) is associated with better longevity than being at "normal" weight — a phenomenon called the obesity paradox.

4. Ethnic and genetic variation. These formulas were primarily developed using data from Western populations. Body composition norms vary meaningfully across ethnicities — for example, South Asian populations tend to carry more visceral fat at lower BMI values, while some Polynesian populations carry more muscle mass at higher weights. One-size-fits-all formulas cannot capture this diversity.

5. People in calorie deficit. If you are currently dieting, you might be holding extra water weight, or you might have lost some muscle along with fat. Hitting your "ideal weight" while having lost significant muscle tissue is not the same as hitting it with healthy body composition. The number on the scale tells you almost nothing about what that weight is made of.

Setting the right weight goal is more art than science, and it is one of the things I spend the most time on with new clients. Get it wrong and you set yourself up for frustration. Get it right and you build momentum that carries you through the tough weeks.

Here is the framework I use. Step 1: Calculate the formula average — that gives you a general reference point. Step 2: Adjust for body composition. If you carry above-average muscle mass, add 3–8 kg to the formula result. If you have a smaller frame or less muscle, the formula result might be right or even slightly high. Step 3: Set a range, not a single number. Your goal should be something like "75–80 kg," not "exactly 77 kg." Bodies fluctuate, and obsessing over a precise number is a recipe for frustration.

Step 4: Set short-term milestones. If your current weight is 95 kg and your target range is 78–83 kg, that is a 12–17 kg journey. Do not think about the end — think about the next 4 weeks. At a healthy rate of 0.3–0.5 kg per week, your first milestone is losing about 1.5–2 kg in the next month. That is achievable. It is motivating. And once you hit it, you set the next milestone.

The most important thing I have learned from years of training clients: the right goal weight is one that you can maintain without suffering. If maintaining a weight requires extreme restriction, constant hunger, and cutting out everything enjoyable about food, it is not your ideal weight — it is an unsustainable target that you will bounce back from. A sustainable weight you can maintain year-round while enjoying life is worth more than an impressive number you hold for two weeks before the rebound.

If I could change one thing about how the fitness industry communicates, it would be this: stop obsessing over scale weight. The number on the scale tells you one thing — how much gravitational force the Earth exerts on your body. It tells you nothing about what that weight is made of, and what it is made of is what actually matters for your health and appearance.

I have a story that illustrates this perfectly. A client came to me wanting to lose 10 kg. She was 72 kg at 165 cm, and the ideal weight formulas said she should be around 58 kg. Over 6 months of strength training and nutrition coaching, her weight went from 72 kg to... 69 kg. Only 3 kg down on the scale. She was initially disappointed until I showed her the body fat measurements: she had gone from 32% body fat to 24%, lost 6 kg of fat, and gained 3 kg of muscle. She looked completely different. Her clothes fit differently. Her energy was through the roof. But the scale barely moved.

This scenario is incredibly common, especially in the first 6–12 months of serious training. That is why I track body fat percentage, waist circumference, and progress photos alongside scale weight for every single client. The scale is one data point — useful but deeply incomplete. Two people at the same height and the same weight can have completely different health profiles depending on their body composition.

My advice: weigh yourself for data, but do not let the scale be your primary success metric. Use our body fat calculator and BMI calculator to get the full picture. Your ideal "weight" is really your ideal body composition — and that cannot be captured by a single number.

Setting weight goals for clients is one of the most consequential decisions a personal trainer makes, because it directly affects motivation, adherence, and long-term success. I have learned through hard experience that overly aggressive targets cause clients to feel like failures when they miss them, while goals set too low leave potential on the table and make clients feel like they are not being challenged.

Here is my actual process. In the first consultation, I run the ideal weight formulas and share all four results with the client. Then I say something like: "These formulas suggest a range of 70–75 kg for your height. But we need to adjust for you personally — how much muscle you carry, your frame size, and what you can realistically maintain." Then we look at body fat percentage and talk about what feels sustainable.

I set goals in 4-week blocks. The first block might target 0.3–0.5 kg of weight loss per week. At the end of 4 weeks, we reassess: how did the scale trend? How did body fat change? How did energy levels and gym performance hold up? If everything is tracking well, we continue. If the client is miserable, constantly hungry, or performance is tanking, we ease up. This iterative approach is infinitely more effective than saying "lose 15 kg in 3 months" on day one.

The Megin measurement tracking module records every weigh-in, body fat measurement, and circumference reading, then generates progress charts automatically. This means I can show a client their actual trend line — not just today's number — which keeps the conversation grounded in data rather than emotion. When a client gets discouraged because the scale went up 0.5 kg this week, I can pull up the chart and show them that they are still down 3 kg over the last 8 weeks. Context is everything.