Ideal Weight Calculator

Last updated: April 2026

Unit system

Sex

Height

Ideal weight

73.2 kg / 161.3 lb

Formula

Height used70.1 in

FormulaDevine formula

Interpretation

The Devine formula gives a simple ideal body weight estimate from height and sex. It is useful as a reference point, but it does not account for muscle mass, frame size, age, or individual health context.

Related calculators:

BMI Calculator
Body Fat Percentage Calculator
Lean Body Mass Calculator

What is ideal body weight?

Ideal body weight is an estimate of body weight based on height and sex. It is commonly used as a quick clinical reference, not as a fixed target for every person.

How is ideal weight calculated?

This calculator uses the Devine formula. For men, ideal weight in kilograms is 50 + 2.3 x every inch over 5 feet. For women, it is 45.5 + 2.3 x every inch over 5 feet.

When to use ideal weight

Ideal weight can be a helpful comparison point alongside BMI, body fat percentage, waist measurement, and fitness goals.

Limitations

The Devine formula does not measure body composition. Athletes, older adults, and people with different frame sizes may have healthy weights above or below this estimate.

About this calculator

The Ideal Weight Calculator estimates target weight ranges using common height-based formulas and BMI-based ranges. It is useful for comparing methods, but it should be treated as a planning reference rather than a medical target. Use this expanded guide when you need more than a quick result. It explains the assumptions behind the Ideal Weight Calculator, the records to gather, and the decisions the estimate can support. It is especially useful for adults comparing height-based weight formulas and understanding why different methods produce different target weights. The strongest use of the page is scenario comparison: change one input at a time, compare the output, and keep a note of which assumption changed.

Ideal weight estimate method

Different ideal weight formulas use height, sex, and sometimes frame assumptions. BMI-based ranges convert a target BMI range into a weight range. The calculator result depends on the quality of the inputs and on the rule set or formula selected in the calculator above. For practical use, treat the output as a structured estimate: start with the core inputs, review the main outputs, then test the decision points that matter most to your situation. Key decisions include which formula is being shown, whether a target is realistic, how to treat formula results alongside health and body composition.

BMI-based weight = target BMI x height squared
formula result depends on selected method and height
better estimate = accurate inputs + correct rule set + realistic assumptions
scenario difference = revised result - original result

How to use the ideal weight calculator

Enter height and sex if required by the selected formula.
Choose metric or imperial units.
Review several formula estimates if available.
Compare the result with BMI, body fat, waist measurement, and health goals.
Use the output as a discussion point rather than a fixed target.
Gather the main inputs first: height, sex if required, formula choice.
Check supporting records such as current height and weight and health goals before relying on a final number.
Enter one realistic scenario first, using conservative assumptions where the future is uncertain.
Review the main outputs: formula-based estimate, BMI-based range, comparison with current weight.
Run at least one alternative scenario so you can see which input changes the answer most.
Compare the result with NHS healthy weight guidance for context or the relevant contract, bill, statement, or professional document.
Keep the calculation date and assumptions with your notes so you can revisit the estimate when rates, rules, or circumstances change.

Worked example

BMI target estimate

Input: Height 1.70m and target BMI 22

Calculation: 22 x 1.70^2 = 63.6kg

Result: A BMI 22 target corresponds to about 63.6kg for that height.

Formula comparison scenario

Input: The same height is entered into several ideal-weight formulas.

Calculation: Each formula returns a different estimate.

Result: The range shows why ideal weight should not be treated as a single exact target.

BMI range scenario

Input: A target BMI range is converted into weight for the user height.

Calculation: Target BMI is multiplied by height squared.

Result: The output gives a broader range than a single formula.

Why formulas differ

Older ideal weight formulas were often developed for clinical dosing or insurance tables rather than modern personal health planning. That is why several formulas can give different answers for the same person.

What to check before relying on the result

A useful Ideal Weight Calculator result starts with the same evidence you would use if you were checking the answer manually. The calculator can organise the arithmetic, but it cannot know whether a payslip is final, a bill is estimated, a quote excludes fees, or a personal circumstance has changed since the last statement.

Before making a decision, compare the calculator result with the source document that controls the real outcome. For this topic, that usually means checking NHS healthy weight guidance for context. If there is a difference between the calculator and an official statement, contract, assessment, or professional advice, treat the official document as the stronger source.

current height and weight: Use this as supporting evidence for the calculation. If it is out of date, estimated, or based on a different period, the calculator output may look precise while still being wrong for the decision.
health goals: Use this as supporting evidence for the calculation. If it is out of date, estimated, or based on a different period, the calculator output may look precise while still being wrong for the decision.
body composition notes: Use this as supporting evidence for the calculation. If it is out of date, estimated, or based on a different period, the calculator output may look precise while still being wrong for the decision.
clinician or dietitian advice: Use this as supporting evidence for the calculation. If it is out of date, estimated, or based on a different period, the calculator output may look precise while still being wrong for the decision.

Inputs that usually change the answer

The most important input is not always the largest number on the form. Sometimes a date, threshold, percentage, eligibility flag, or timing assumption changes the result more than the headline amount. This is why scenario testing is more useful than a single calculation.

Input	Why it matters	What to double-check
height	It feeds directly into the estimate or changes which rule is applied.	Check the period, units, eligibility, and whether the figure is final or estimated.
sex if required	It feeds directly into the estimate or changes which rule is applied.	Check the period, units, eligibility, and whether the figure is final or estimated.
formula choice	It feeds directly into the estimate or changes which rule is applied.	Check the period, units, eligibility, and whether the figure is final or estimated.
current weight	It feeds directly into the estimate or changes which rule is applied.	Check the period, units, eligibility, and whether the figure is final or estimated.
unit system	It feeds directly into the estimate or changes which rule is applied.	Check the period, units, eligibility, and whether the figure is final or estimated.

How to interpret the output

The output should be read as a decision aid, not just a number. For Ideal Weight Calculator, the useful question is often what the result means for timing, affordability, eligibility, comparison, or next steps.

formula-based estimate: Use this output alongside the other results rather than in isolation. A monthly amount, percentage, date, or payback figure can look acceptable until fees, timing, evidence, or eligibility conditions are added.
BMI-based range: Use this output alongside the other results rather than in isolation. A monthly amount, percentage, date, or payback figure can look acceptable until fees, timing, evidence, or eligibility conditions are added.
comparison with current weight: Use this output alongside the other results rather than in isolation. A monthly amount, percentage, date, or payback figure can look acceptable until fees, timing, evidence, or eligibility conditions are added.
method spread: Use this output alongside the other results rather than in isolation. A monthly amount, percentage, date, or payback figure can look acceptable until fees, timing, evidence, or eligibility conditions are added.

Scenarios worth comparing

A single estimate is a snapshot. A better approach is to save a base case, then adjust one assumption at a time. This shows whether the result is stable or whether a small change in timing, rate, usage, income, or cost creates a very different answer.

Scenario	Change one assumption	What the comparison shows
Base case	Use the best current evidence.	Shows the result you would expect if nothing important changes.
Conservative case	Use lower income, higher cost, slower growth, or less favourable timing.	Shows whether the decision still works with less optimistic assumptions.
Improved case	Use the realistic upside, such as lower cost, better rate, higher usage, or stronger evidence.	Shows the potential benefit without treating it as guaranteed.

Common mistakes and edge cases

Most errors come from using the right formula with the wrong assumption. Dates can be counted differently, rates can change, official thresholds can move, and real bills or contracts often include conditions that a simple calculator cannot infer automatically.

Ideal-weight formulas were not designed for every body type.: Check this point before using the estimate for a payment, claim, purchase, application, employment decision, or health-related decision.
Lower is not always healthier.: Check this point before using the estimate for a payment, claim, purchase, application, employment decision, or health-related decision.
Muscle mass and frame size can change interpretation.: Check this point before using the estimate for a payment, claim, purchase, application, employment decision, or health-related decision.
Medical conditions and pregnancy need professional guidance.: Check this point before using the estimate for a payment, claim, purchase, application, employment decision, or health-related decision.

Next steps after calculating

Once you have a result, write down the key assumptions and compare them with NHS healthy weight guidance for context. If the number affects a deadline, tax return, benefit claim, employment issue, medical question, finance agreement, or major purchase, use the calculator as preparation for a more formal check.

For lower-stakes use, the next step may simply be comparing two or three scenarios. For higher-stakes use, the next step should be checking the official guidance, speaking to the relevant organisation, or getting qualified advice before acting.

Important edge cases

Ideal-weight formulas were not designed for every body type.
Lower is not always healthier.
Muscle mass and frame size can change interpretation.
Medical conditions and pregnancy need professional guidance.

Limitations

This guide is general information only and is not medical advice. This is general health information and not medical advice. The calculator is designed to support understanding and planning, but it cannot verify documents, predict future rule changes, or account for every exception. Use it as an estimate and check the official source before acting where the result matters.

It does not account for muscle mass, body shape, ethnicity, pregnancy, or medical history.
It is not suitable for diagnosing health conditions.
Speak to a clinician or dietitian for personal targets.
Check NHS healthy weight guidance for context for current rules, rates, definitions, and eligibility where relevant.
Do not rely on a single scenario where income, costs, dates, rates, usage, or health circumstances may change.
Keep records of the inputs used so that the estimate can be reviewed later.

Frequently asked questions

Why are there multiple ideal weights?

Each formula uses different assumptions, so the result should be viewed as a range of estimates.

Is lower always better?

No. Too low a weight can also carry health risks.

Can I use this for children?

Adult formulas should not be used for children; children need age and sex growth centiles.

Which ideal-weight formula is best?

No formula is best for everyone. They are reference points, not personal prescriptions.

Can I use this after pregnancy?

Post-pregnancy weight and recovery should be discussed with a clinician if there are concerns.

Why does the result differ from BMI?

BMI-based ranges and named ideal-weight formulas use different assumptions.

Related calculators

BMI Calculator
Healthy Weight Calculator
Body Fat Percentage Calculator
BMR Calculator

What does this mean?

This calculator is designed to help you understand the likely number before you make a decision or start an application.

Your result should be checked against official UK guidance, especially if your circumstances include dependants, exemptions, prior leave, or a complex immigration history.

Treat the figure as a planning tool rather than legal advice. Where the answer affects an application deadline or major payment, speak to an authorised adviser.

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