Ideal Weight Calculator

Formula profile:

Accepted values: male coefficients or female coefficients; choose the set your reference names.

Height:

Examples: 172 cm, 68 in, or 5 ft 8 in; switching units converts the same height.

Weight unit:

Choose kg or lb for the derived weight results; an entered current weight converts when you switch units.

Target BMI:

Enter 18.5 to 24.9; default 22.0 gives a midpoint-style BMI target.

BMI

Current weight:

Enter current weight in the selected weight unit, or leave blank to hide comparison.

Frame size:

Options: Small -10%, Medium no shift, Large +10%; the next mode controls where it applies.

Frame adjustment mode:

Choose Hamwi only for the classic adjustment; use all formulas only to match legacy output.

Under-5 ft handling:

Subtract mode lowers formulas below 5 ft; clamp mode holds each formula at its base constant.

Area	Badge	Readout	Detail	Copy
{{ card.title }}	{{ card.badge }}	{{ card.headline }}	{{ card.detail }}

Formula	{{ weightUnit.toUpperCase() }}	kg	lb	Vs consensus	Current gap	How to read it	Copy
{{ row.name }} {{ row.shortNote }}	{{ formatWeight(row.selected) }}	{{ formatWeight(row.kg) }}	{{ formatWeight(row.lb) }}	{{ row.deltaFromConsensusText }}	{{ row.deltaFromCurrentText }}	{{ row.guidance }}

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Ideal body weight is a reference estimate built from height, not a verdict about the best weight for a specific adult. The word "ideal" can sound personal, but the classic equations are better understood as clinical and nutrition shortcuts from older height-weight references. They reduce body size to height plus a male or female coefficient set, which makes them easy to compare and cite, but too narrow to judge health, fitness, or body composition on their own.

Four names appear often in ideal-weight discussions: Devine, Hamwi, Robinson, and Miller. Each starts at a 5-foot height anchor, assigns a base weight there, and adds or subtracts a fixed amount for every inch away from the anchor. The base values and per-inch slopes differ, so the same height can produce a small cluster of answers rather than one settled target.

Core reference concepts for ideal body weight
Concept	What it adds	Main caution
Classic formula estimate	A single height-based weight from one named equation.	It reflects the equation, not an individual body-composition measurement.
Formula band	The spread between several classic equations at the same height.	A narrow band does not turn the estimate into a diagnosis or a goal.
Adult BMI corridor	The weight span that maps to adult BMI 18.5 to 24.9.	BMI is a screening measure and should be read with other health information.
Current-weight comparison	A way to see whether a present weight falls below, inside, or above a reference band.	Being outside one band and inside another is common when references use different math.

Body mass index, or BMI, answers a nearby but different question. BMI divides weight by height squared, then compares the result with adult screening categories. When BMI is converted back into a weight range for one height, the range often becomes wider than the classic formula cluster. That is expected because BMI categories are broad adult screening cutoffs, while the named formulas are older linear rules.

The useful habit is to compare references instead of chasing the smallest or most flattering number. A named clinical protocol may require Devine. A nutrition note may prefer Hamwi-style framing. A general adult screening discussion may lean more on the BMI corridor. When those references disagree, the difference usually reflects the reference system, not a data-entry failure.

Height-only estimates have predictable blind spots. They do not know whether weight comes from muscle, fat, fluid, pregnancy, medical treatment, disability, athletic training, or growth stage. They are most defensible as adult planning context, and they become safer when the formula name, BMI corridor, current weight, and limitations stay visible together.

How to Use This Tool:

Start with the basic adult reference settings, then use the advanced controls only when they match the source or protocol you are comparing against.

Set Formula profile to the male or female coefficient set named by the reference you are comparing against. This choice changes all four formula rows.
Enter Height in cm, in, or ft/in. Results appear only when the height can be converted to a positive centimeter value.
Check height units before interpreting any result. A total-inch entry and a ft/in entry can look similar but move every formula, BMI marker, chart, and export.
Choose Weight unit as kg or lb. Switching units converts the derived weights and an entered Current weight without changing the underlying calculation.
Keep Target BMI inside 18.5 to 24.9. The target marker is one BMI-derived weight inside the adult corridor and does not change Devine, Hamwi, Robinson, or Miller.
Open Advanced only when you need Current weight, Frame size, Frame adjustment mode, or Under-5 ft handling.
The recommended frame mode applies small or large frame adjustments to Hamwi only; All formulas is mainly for matching legacy output.
Read Planning Summary first for the consensus value, formula band, healthy corridor, optional current-weight status, and adult-reference caution.
Use Formula Comparison, Formula Weights, and Weight Corridor when you need a named row, a copyable table, or a visual check of formula-band and BMI-band overlap.
If the result looks implausible, recheck height, unit, coefficient profile, frame mode, and under-5 ft setting before using the charts or exports.
Use a named formula when a protocol requires it. Treat Consensus Ideal Weight as a midpoint, not as a medical target.

Interpreting Results:

Consensus Ideal Weight is the average of Devine, Hamwi, Robinson, and Miller for the current settings. It is a convenient midpoint, not proof that the average is more medically correct than a named row. If a reference or dosing guide specifies Devine, Hamwi, Robinson, or Miller, use that row.

Formula band is the lowest-to-highest span across the four formula rows. Healthy corridor is the adult BMI 18.5 to 24.9 weight span at the same height. The two bands can overlap, sit partly apart, or diverge enough that one reference contains a current weight while the other does not.

How to read ideal-weight output fields
Output	Trust it for	Verify before relying on it
`Consensus Ideal Weight`	A midpoint across four classic formulas.	The source you are comparing against may require one named formula instead.
`Formula band`	How much the classic equations disagree at the entered height.	Frame and under-5 ft settings can widen or shift the band.
`Healthy corridor`	The adult BMI healthy-weight span converted to the selected unit.	BMI does not measure fat distribution, muscle mass, edema, pregnancy status, or growth stage.
`Current vs target`	A present-weight comparison against the formula band, target BMI, and BMI corridor.	Mixed labels such as `Inside BMI band only` mean references disagree, not that the tool is contradicting itself.
`Weight Corridor`	A visual check of formula-band and BMI-band overlap.	Use the numeric tables when a value is near a boundary.

The main false-confidence risk is treating a height-based adult reference as a health verdict. Confirm the height and unit, keep the BMI corridor visible, and treat current-weight status as a starting comparison that may need clinical context.

Technical Details:

Classic ideal-weight equations are linear height rules. They start with a base weight at 60 inches and add or subtract a fixed amount for each inch away from that anchor. The coefficient profile selects the base and slope set, while frame size applies a multiplier according to the chosen frame mode.

BMI-derived weights follow a squared-height rule. The BMI value is multiplied by height in meters squared, so the adult BMI corridor widens with height more quickly than the classic linear formulas. This difference explains why a taller person's BMI corridor can be broad even when the four formula rows stay close together.

Formula Core:

Use centimeters as the normalized height, then convert the distance from the 5-foot anchor into inches. The under-5 ft setting decides whether that distance may be negative or is clamped at zero for the classic formulas.

\begin{array}{lcl} h_{ex} & = & \frac{h_{cm} - 152.4}{2.54} \\ W_{formula} & = & max (0, b + s \times h_{ex}) \times m \\ W_{BMI} & = & BMI \times {h_{m}}^{2} \\ W_{consensus} & = & \frac{W_{Devine} + W_{Hamwi} + W_{Robinson} + W_{Miller}}{4} \end{array}

Formula symbols and units
Symbol	Meaning	Unit or rule
`h_cm`	Height after unit conversion.	Centimeters.
`h_ex`	Inches above or below 5 ft.	May be negative in subtract mode; zero or positive in clamp mode.
`b`	Formula base weight at 5 ft.	Kilograms.
`s`	Formula step per inch from the anchor.	Kilograms per inch.
`m`	Frame multiplier.	0.9 for small, 1.0 for medium, 1.1 for large when applied.
`h_m`	Height for BMI math.	Meters.

Classic ideal-weight coefficients
Formula	Male coefficients	Female coefficients	Reading note
Devine	`50 + 2.3 * h_ex` kg	`45.5 + 2.3 * h_ex` kg	Often used when a dosing or clinical source names Devine directly.
Hamwi	`48 + 2.7 * h_ex` kg	`45.5 + 2.2 * h_ex` kg	The recommended frame mode applies small or large frame changes here only.
Robinson	`52 + 1.9 * h_ex` kg	`49 + 1.7 * h_ex` kg	A revision that often lands near the lower or middle part of the cluster.
Miller	`56.2 + 1.41 * h_ex` kg	`53.1 + 1.36 * h_ex` kg	A higher base with a gentler per-inch slope.

For a 172 cm adult using male coefficients, the height offset is about 7.7 inches above the 5-foot anchor. With a medium frame and subtract mode, the four rows are about 67.7 kg, 68.8 kg, 66.7 kg, and 67.1 kg, giving a consensus of about 67.6 kg. The adult BMI corridor at the same height is about 54.7 to 73.7 kg, and a target BMI of 22.0 converts to about 65.1 kg.

Boundary rules used by the ideal-weight calculator
Rule	Boundary	Effect on the result
Valid height	Positive numeric height required	No result table is shown until height can be converted to centimeters.
Adult BMI corridor	18.5 to 24.9	Creates the healthy-weight corridor for the entered height.
Target BMI	Limited to 18.5 through 24.9	Values outside the adult corridor are treated as the nearest corridor boundary.
Current-weight status	Below, inside, or above each band with a 0.05 kg tolerance	Very small rounding differences near a boundary do not flip the label.
Short-height subtract mode	Negative `h_ex` allowed	Classic formulas can fall below their 5-foot base weights.
Short-height clamp mode	`h_ex` cannot go below zero	Classic formulas stay at their 5-foot base weights for shorter heights.
Common adult-range warning	Below 120 cm or above 230 cm	The caution text tells readers to treat the result as a rough estimate.

Unit conversion uses 2.54 cm per inch and 0.45359237 kg per pound. Displayed weights round to one decimal place, while copied tables and JSON can carry more precision for audit or comparison.

Limitations and Privacy Notes:

Ideal-weight formulas and adult BMI categories are informational references. They are not professional medical advice, diagnosis, treatment guidance, or a substitute for a clinician who can consider body composition, medical history, medications, pregnancy, edema, disability, growth stage, and cultural or population context.

Use adult BMI ranges for adults; children and teens need age- and sex-specific growth-chart interpretation.
Use the named formula required by a protocol when medication dosing, nutrition support, or clinical documentation depends on a specific reference.
Do not use these estimates alone for eating-disorder recovery, pregnancy, edema, competitive athletics, or major body-composition decisions.
The calculation and exports run in the browser. Changed inputs can appear in the page URL, so do not share a link if you do not want those measurements included.

Worked Examples:

Default adult reference check. With male coefficients, height 172 cm, medium frame, Hamwi-only frame mode, subtract mode, and target BMI 22.0, Consensus Ideal Weight is about 67.6 kg. The Formula band is about 66.7 to 68.8 kg, while the Healthy corridor is about 54.7 to 73.7 kg. The formula rows cluster tightly, but the BMI corridor remains much broader.

Current weight inside BMI range but above formulas. With female coefficients, height 165 cm, small frame, Hamwi-only frame mode, and current weight 62.0 kg, the formula band is about 50.8 to 59.8 kg and the healthy corridor is about 50.4 to 67.8 kg. The current-weight label reads as an inside-BMI-only type of result, so the two references are giving different context rather than a single pass or fail.

Under-5 ft setting changes the formula rows. At 150 cm with male coefficients and medium frame, subtract mode gives formula rows from about 45.4 to 54.9 kg. Clamp mode holds rows at their 5-foot bases, about 48.0 to 56.2 kg. The Healthy corridor stays about 41.6 to 56.0 kg because BMI math does not use the 5-foot formula anchor.

Out-of-range target BMI recovery. If a target BMI above 24.9 is typed, the target-weight calculation uses the top of the adult corridor. Check the Target BMI badge and the Healthy corridor row before treating that marker as a personal goal.

FAQ:

Why do four formulas give different ideal weights?

Devine, Hamwi, Robinson, and Miller use different base weights and per-inch steps. The Formula band shows that disagreement instead of hiding it behind one number.

Should I use the consensus value or a named formula?

Use the named row when a protocol, article, clinician, or dosing guide specifies one. Use Consensus Ideal Weight only as a quick midpoint across the four displayed formulas.

Why can my current weight be inside BMI but outside the formula band?

The formula band and BMI corridor come from different math. A mixed Current vs target status means those references disagree at the entered height.

What does frame size change?

Small frame applies a 10% decrease and large frame applies a 10% increase when the selected frame mode allows it. The recommended mode applies that adjustment to Hamwi only.

Why did the results change after switching units?

They should change only by rounding when the same physical height and weight are converted correctly. Recheck whether inches were entered as total inches or as the inches part of ft/in.

Does the calculation use a server?

The calculation, tables, charts, and exports run in the browser. Inputs can be reflected in the page URL, so shared links may reveal the measurements you entered.

Glossary:

Ideal body weight: A height-based reference weight from a published equation or table-derived rule.
Formula band: The span from the lowest to the highest classic formula result for the current settings.
Consensus Ideal Weight: The arithmetic mean of the Devine, Hamwi, Robinson, and Miller rows.
Adult BMI corridor: The weight span at the entered height that corresponds to BMI 18.5 to 24.9.
Target BMI: One selected BMI value inside the adult corridor, converted into a weight.
Under-5 ft handling: The setting that either subtracts below the 5-foot formula anchor or clamps classic formulas at their base constants.

References:

Adult BMI Categories, Centers for Disease Control and Prevention, March 19, 2024.
Statement on Ideal Body Weight, Parenteral and Enteral Nutrition Group, 2022.
The Origin of the "Ideal" Body Weight Equations, Annals of Pharmacotherapy, September 2000.
Ideal Body Weight: A Commentary, Clinical Nutrition ESPEN, December 2021.