# BMI Weight Loss Calculator

> Set a target BMI and find the weight you need to reach it. Enter current stats and your goal BMI below.

**Last updated:** September 2026
**URL:** https://bodyhealthcalculator.com/bmi-weight-loss-calculator
**Category:** Weight & Body Composition

## How it works

Target weight = target BMI × height(m)². Weight to lose = current weight − target weight.

## Setting a target weight from goal BMI

If you know your height and a target BMI, you can calculate the exact weight that produces that BMI: target weight = target BMI × height (m)². The calculator reverses the usual BMI formula to answer "how much should I weigh to reach BMI X?" Common goal BMIs include 24 (upper normal range), 22 (mid-normal), and 25 (overweight threshold). Your provider may recommend a different target based on muscle mass, age, and health conditions.

The calculator also shows how many kilograms or pounds you need to lose or gain from your current weight to reach the target.

Reverse BMI targets assume height is stable; spinal compression in older adults slightly reduces height and therefore calculated target weight. Maintenance after reaching target BMI requires reversing deficit gradually, not returning to prior habits overnight. Waist-to-height ratio may stay elevated briefly after BMI normalizes if abdominal fat was high at baseline.

Sources: [1]

## Setting realistic weight loss goals

Moving from BMI 32 to BMI 24 requires losing roughly 25% of body weight for most heights, a substantial but achievable goal over 6 to 18 months with sustained lifestyle change or medical support. Losing 5 to 10% of current body weight produces meaningful health improvements even if you never reach "normal" BMI. Do not dismiss partial progress because the ultimate goal seems far away.

A safe rate is generally 0.5 to 1.0 kg (1 to 2 lb) per week. Faster loss increases muscle wasting and gallstone risk unless medically supervised.

Sources: [1] [2]

## Goal weight is not the whole story

Two people at the same goal BMI can look and feel very different depending on muscle mass and fat distribution. Pair BMI targets with waist-to-height ratio and body fat percentage when possible. Ideal body weight formulas (Devine, Robinson) may give different target weights than a BMI of 24 for the same person. Compare multiple estimates and choose a sustainable goal.

If you have history of eating disorders, consult a mental health professional before setting numeric weight targets. Process goals (daily steps, protein intake, strength sessions) may be healthier than scale targets.

Sources: [2] [3]

## Choosing a target BMI responsibly

CDC adult categories place normal BMI between 18.5 and 24.9 kg/m², but optimal weight for an muscular individual may sit at the upper end of normal or slightly into overweight without adverse labs. Devine and Robinson ideal body weight formulas sometimes disagree with BMI 24 by several kilograms for the same height. Averaging multiple estimates reduces reliance on a single legacy equation.

Goldstein noted that health improvements appear at 5 to 10% loss even when patients never reach normal BMI. Setting an intermediate target BMI can improve motivation.

If you have diabetes, cardiovascular disease, or a history of disordered eating, ask a clinician to help set weight goals rather than relying on reverse BMI math alone.

Sources: [1] [2]

## Reverse BMI math example

Target weight (kg) = target BMI × height (m)². A 1.70 m person targeting BMI 24 needs 24 × 2.89 ≈ 69.4 kg. Moving from BMI 30 to 24 at that height requires losing about 17 kg, which at 0.5 kg/week implies roughly 34 weeks if adherence is perfect.

Partial progress still matters: dropping from BMI 32 to 29 can improve blood pressure even if normal BMI remains distant.

Combine reverse BMI targets with waist goals because two people at BMI 24 can differ in central adiposity.

Sources: [1] [2]

## Reverse BMI formula and target ranges

Rearranging BMI = weight / height² gives weight = BMI × height². At 1.70 m, BMI 18.5 corresponds to 53.5 kg, BMI 24.9 to 72.0 kg, and BMI 30 to 86.7 kg. A healthy-category range is more honest than treating BMI 24 as one universally ideal target.

Reverse BMI math says nothing about the time, method, composition, or safety of weight change.

For a person at 90 kg and 1.70 m, current BMI is 31.1. A target BMI of 28 gives 80.9 kg, requiring about 9.1 kg or 10.1% loss. A target BMI of 24 gives 69.4 kg, requiring 20.6 kg or 22.9% loss. The larger goal may require staged treatment and medical support. It is a unit conversion anchored to a screening index. Health improvements can occur before someone reaches the standard healthy category.

*Target weights at 1.70 m*

| Target BMI | Target weight | Context |
| --- | --- | --- |
| 18.5 | 53.5 kg | Lower healthy-category boundary |
| 22 | 63.6 kg | Middle reference point |
| 24.9 | 72.0 kg | Upper healthy-category boundary |
| 28 | 80.9 kg | Possible intermediate target |

*Target BMI and corresponding weight status (WHO). Use with your height to set a goal weight.*

| Target BMI | Category |
| --- | --- |
| 18.5 | Lower bound of normal weight |
| 21.0 | Mid-normal (common goal) |
| 24.9 | Upper bound of normal weight |
| 25.0 | Overweight threshold |

Sources: [1] [4]

## Alternatives, population limits, and safety

Waist-to-height ratio adds central fat distribution, while body composition distinguishes fat from lean tissue. A muscular adult can be healthy above BMI 25, and someone within the healthy category can have high waist or metabolic risk. Targets should reflect the measure that needs improvement.

Adult reverse BMI targets do not apply during pregnancy, childhood, or adolescence. Older adults with frailty, athletes, people with eating disorders, and patients with edema, amputation, or serious illness need individualized assessment. Deliberate loss can be harmful when reserve or muscle is already low.

CDC describes gradual loss of about one to two pounds per week as more sustainable for many adults, but rate should be personalized. Very rapid loss can increase gallstone, nutrient, and lean-tissue risk and may require medical supervision.

Do not set a target below BMI 18.5 without specialist guidance. Seek help for dizziness, fainting, missed periods, bingeing, purging, severe restriction, or distress around weight. A sustainable plan prioritizes health, function, and maintenance over reaching an exact decimal.

Target weight should be recalculated only when measured height changes or the clinical goal changes, not after every weigh-in. Progress is current weight minus target weight, while percentage progress requires a clearly defined starting point. Avoid projecting a completion date by dividing kilograms by an assumed weekly rate for a long period. Weight loss commonly slows as energy needs, adherence, and physiology change, and maintenance phases can be part of a successful plan.

Use a target range when normal hydration and day-to-day variation make one exact weight unrealistic.

A target BMI can be useful for planning eligibility thresholds or discussing a broad range, but it should not become a pass-fail test. Reaching an intermediate BMI with improved blood pressure and fitness may be a better outcome than reaching a lower number through unsustainable restriction. Persistent metabolic disease can require treatment even after BMI enters the healthy category. Reassess outcomes at each stage. A narrow decimal goal creates false precision, while a range allows maintenance behavior to guide decisions after the initial loss.

Sources: [1] [2] [3] [4] [5] [6] [7]

## How to use this calculator

Enter your current height and weight, then set your target BMI (default 24). The result shows target weight and the difference from your current weight. Use the calorie deficit calculator to estimate how long reaching your goal might take at a chosen daily deficit.

Goal BMI should not go below 18.5 without medical supervision even if math suggests a lower target weight.

Reverse BMI math assumes constant height; osteoporosis-related height loss in elders lowers calculated target weight without changing ideal composition. Goldstein modest weight loss data support celebrating partial progress toward BMI 24 even when final target remains several kilograms away.

Sources: [1]

## FAQ

### What target BMI should I use?

24 is a common goal within the normal range. Consult a provider for personalized targets.

## References

1. CDC. [About Adult BMI](https://www.cdc.gov/bmi/adult-calculator/bmi-categories.html)
2. Goldstein, 2009. [Benefits of modest weight loss](https://pubmed.ncbi.nlm.nih.gov/12566193/)
3. CDC. [Healthy Weight: Losing Weight](https://www.cdc.gov/healthyweight/losing_weight/index.html)
4. NHLBI. [Aim for a Healthy Weight](https://www.nhlbi.nih.gov/health/heart-healthy-living/healthy-weight)
5. Jensen et al.. [Managing overweight and obesity in adults: guideline executive summary](https://doi.org/10.1002/oby.20821)
6. WHO. [Waist circumference and waist-hip ratio: WHO expert consultation](https://www.who.int/publications/i/item/9789241501491)
7. NHLBI. [Clinical guidelines on identification and treatment of overweight and obesity](https://www.nhlbi.nih.gov/files/docs/guidelines/ob_gdlns.pdf)

## Related

- [bmi calculator](https://bodyhealthcalculator.com/bmi-calculator.md)
- [calorie deficit calculator](https://bodyhealthcalculator.com/calorie-deficit-calculator.md)
- [ideal body weight calculator](https://bodyhealthcalculator.com/ideal-body-weight-calculator.md)