People type this into search as an ideal weight calculator.
Ideal body weight here is a height equation, often used when someone is estimating a drug dose. It is one number from a formula. The CDC healthy-weight band on the same card is wider, and it is a screening range for adults 20 and older. Muscle, age, and frame sit outside both formulas. Ask a clinician before you treat either number as a goal.
Three results from one height
The ideal body weight calculator prints Devine as the headline, then Robinson, then the two ends of the CDC band.
Devine, as reprinted in the Peterson review of the 1974 equation:
male = 50 kg + 2.3 kg × inches over 5 feet
female = 45.5 kg + 2.3 kg × inches over 5 feet
Robinson, from the 1983 paper:
male = 51.65 kg + 1.85 kg × inches over 5 feet
female = 48.67 kg + 1.65 kg × inches over 5 feet
The CDC adult BMI categories call 18.5 to 24.9 a healthy weight for adults 20 and older.
low kg = 18.5 × metres × metres
high kg = 24.9 × metres × metres
Height enters as centimetres. Inches are centimetres ÷ 2.54. Five feet is 60 inches, which is 60 × 2.54 = 152.4 cm. The sex field stores 1 for the male equation and 0 for the female equation. The card prints that 1 or 0.
On a US visit, kilograms display as pounds with the site factor 2.204622622, one decimal. Centimetres on the detail line display as inches. The input you typed still shows the cm suffix. The formula uses the full division by 2.54. It does not feed the rounded inch label back into the equation.
Fig 1
One height, three readings
Inches over 5 feet feed Devine and Robinson
Devine adds 2.3 kg per inch over 5 feet. Robinson adds 1.85 kg for the male equation and 1.65 kg for the female equation. The CDC band is BMI 18.5 to 24.9.
The BMI calculator goes the other way. You type a weight, and it returns a category. This page types a height and returns weights. The BMI post walks the category cutoffs. Daily energy from a typed weight is the calorie post. Protein from that weight is the protein post.
Example 1: 175 cm, male equation
This is the calculator default.
- equation: 1
- height: 175 cm
Inches: 175 ÷ 2.54 = 68.8976, displayed as 68.9 in
Inches over 5 feet: 68.8976 − 60 = 8.8976
Devine: 50 + 2.3 × 8.8976 = 50 + 20.4646 = 70.46 kg
Pounds: 70.4646 × 2.204622622 = 155.348, displayed as 155.3 lb
Robinson: 51.65 + 1.85 × 8.8976 = 51.65 + 16.4606 = 68.11 kg, displayed as 150.2 lb
BMI area: 1.75 × 1.75 = 3.0625
Low: 18.5 × 3.0625 = 56.65625 kg, displayed as 124.9 lb
High: 24.9 × 3.0625 = 76.25625 kg, displayed as 168.1 lb
The band is 168.1 − 124.9 = 43.2 lb wide. Devine sits 155.3 − 124.9 = 30.4 lb above the low end, and 168.1 − 155.3 = 12.8 lb under the high end. Robinson is 155.3 − 150.2 = 5.1 lb under Devine. Both points are inside the band.
Calculator result
Ideal body weight
- Devine equation
- 1
- Height
- 175 cm
155.3 lb
Devine male ideal body weight
- Robinson 1983 estimate
- 150.2 lb
- CDC healthy-weight low (BMI 18.5)
- 124.9 lb
- CDC healthy-weight high (BMI 24.9)
- 168.1 lb
- Height used
- 68.9 in
- Height in inches
- 68.9 in
If you round 68.8976 inches to 69 before the formula, Devine becomes 50 + 2.3 × 9 = 70.7 kg, which is 70.7 × 2.204622622 = 155.87, displayed as 155.9 lb. That is 0.6 lb above the card. The card keeps the unrounded inches.
Fig 2 · 1/4
175 cm, male equation
Devine is the headline. The CDC band is the wide pair.
Height equations
Devine
155.3 lb
Robinson
150.2 lb
CDC healthy-weight band
BMI 18.5
124.9 lb
BMI 24.9
168.1 lb
Devine is 155.3 lb. Robinson is 150.2 lb.
The healthy-weight band runs from 124.9 lb to 168.1 lb.
Example 2: the same 175 cm, female equation
Only the equation changes, from 1 to 0. Height stays 175 cm. The CDC band does not read the equation, so it stays 124.9 lb to 168.1 lb. The inch line stays 68.9 in.
Devine: 45.5 + 20.4646 = 65.96 kg, displayed as 145.4 lb
Robinson: 48.67 + 1.65 × 8.8976 = 48.67 + 14.6811 = 63.35 kg, displayed as 139.7 lb
The two Devine equations differ by 50 − 45.5 = 4.5 kg at every height, because they share the 2.3 kg slope. 4.5 × 2.204622622 = 9.92 lb. On this card the gap is 155.3 − 145.4 = 9.9 lb.
Robinson’s slopes differ, so the gap is not a fixed 4.5 kg. Here it is 150.2 − 139.7 = 10.5 lb.
Calculator result
Ideal body weight
- Devine equation
- 0
- Height
- 175 cm
145.4 lb
Devine female ideal body weight
- Robinson 1983 estimate
- 139.7 lb
- CDC healthy-weight low (BMI 18.5)
- 124.9 lb
- CDC healthy-weight high (BMI 24.9)
- 168.1 lb
- Height used
- 68.9 in
- Height in inches
- 68.9 in
Example 3: exactly 5 feet, where the slope is zero
5 feet is 152.4 cm. Inches over 5 feet = 0. Both equations return their bases.
| Male equation | Female equation | |
|---|---|---|
| Devine | 50 kg, 110.2 lb | 45.5 kg, 100.3 lb |
| Robinson | 51.65 kg, 113.9 lb | 48.67 kg, 107.3 lb |
| BMI 18.5 | 94.7 lb | 94.7 lb |
| BMI 24.9 | 127.5 lb | 127.5 lb |
| Height on the card | 60 in | 60 in |
Devine male pounds: 50 × 2.204622622 = 110.231, displayed as 110.2. Female: 45.5 × 2.204622622 = 100.310, displayed as 100.3. The gap is 110.2 − 100.3 = 9.9 lb, the same displayed 4.5 kg gap as Example 2.
BMI area: 1.524 × 1.524 = 2.322576. Low: 18.5 × 2.322576 = 42.968 kg, displayed as 94.7 lb. High: 24.9 × 2.322576 = 57.832 kg, displayed as 127.5 lb.
At this height Robinson sits above Devine on both equations. Male: 113.9 − 110.2 = 3.7 lb. Female: 107.3 − 100.3 = 7.0 lb. Example 8 shows the height where that order flips.
Calculator result
Ideal body weight
- Devine equation
- 1
- Height
- 152.4 cm
110.2 lb
Devine male ideal body weight
- Robinson 1983 estimate
- 113.9 lb
- CDC healthy-weight low (BMI 18.5)
- 94.7 lb
- CDC healthy-weight high (BMI 24.9)
- 127.5 lb
- Height used
- 60 in
- Height in inches
- 60 in
Example 4: exactly 6 feet, twelve inches of slope
6 feet is 72 × 2.54 = 182.88 cm. Inches over 5 feet = 12. The card shows 72 in.
Devine male: 50 + 2.3 × 12 = 50 + 27.6 = 77.6 kg, displayed as 171.1 lb
Devine female: 45.5 + 27.6 = 73.1 kg, displayed as 161.2 lb
Robinson male: 51.65 + 1.85 × 12 = 51.65 + 22.2 = 73.85 kg, displayed as 162.8 lb
Robinson female: 48.67 + 1.65 × 12 = 48.67 + 19.8 = 68.47 kg, displayed as 151 lb
The CDC band is the same for both equations: 136.4 lb to 183.6 lb.
From Example 3 to here is 12 inches. Devine’s displayed pounds rise by 171.1 − 110.2 = 60.9, and by 161.2 − 100.3 = 60.9 on the female equation. Unrounded, each inch is 2.3 × 2.204622622 = 5.071 lb, and 12 × 5.071 = 60.85 lb. The 0.05 lb is rounding on the two ends.
Robinson male rises by 162.8 − 113.9 = 48.9 lb. That slope is 1.85 kg per inch, which is 1.85 × 2.204622622 = 4.079 lb, and 12 × 4.079 = 48.94 lb.
Someone who types 183 cm instead of 182.88 is 0.12 cm taller. The card shows 72 in for that too, because 183 ÷ 2.54 = 72.047 rounds to 72.0 at one decimal. Devine male at 183 cm displays as 171.3 lb, which is 0.2 lb above the exact 6-foot result. The formula saw the extra 0.047 inch. The inch label did not.
Example 5: what if the height steps up
Male equation. Each row is the card’s display. The CDC columns ignore the equation, so a female row at the same height would keep them and move Devine and Robinson.
| Height | Inches on the card | Devine | Robinson | BMI 18.5 | BMI 24.9 |
|---|---|---|---|---|---|
| 160 cm | 63 in | 125.4 lb | 126.1 lb | 104.4 lb | 140.5 lb |
| 165 cm | 65 in | 135.4 lb | 134.1 lb | 111 lb | 149.5 lb |
| 170 cm | 66.9 in | 145.4 lb | 142.1 lb | 117.9 lb | 158.6 lb |
| 175 cm | 68.9 in | 155.3 lb | 150.2 lb | 124.9 lb | 168.1 lb |
| 180 cm | 70.9 in | 165.3 lb | 158.2 lb | 132.1 lb | 177.9 lb |
| 190 cm | 74.8 in | 185.3 lb | 174.2 lb | 147.2 lb | 198.2 lb |
From 175 to 180 is 5 cm, about 1.97 inches. Devine moves from 155.3 to 165.3, a gain of 10.0 lb. Two inches of Devine would be about 10.1 lb before rounding. This 5 cm step lands on an even 10.0 lb on the display.
The band stays wider than the gap between Devine and Robinson on every row. At 190 cm the band is 198.2 − 147.2 = 51.0 lb. Devine minus Robinson is 185.3 − 174.2 = 11.1 lb.
Fig 3 · 1/6
Devine male weight as height rises
Pounds on the US card. The slope is 2.3 kg per inch over 5 feet.
pounds
- Devine
| Point | Devine |
|---|---|
| 150 | 105.4 |
| 160 | 125.4 |
| 170 | 145.4 |
| 175 | 155.3 |
| 180 | 165.3 |
| 190 | 185.3 |
150 cm is 105.4 lb. 170 cm is 145.4 lb.
180 cm is 165.3 lb. 190 cm is 185.3 lb.
The 150 cm point is Example 6. It is under 5 feet, and the line still plots it, because the calculator still returns a number.
Fig 4 · 1/2
Devine, both equations
The female equation stays 4.5 kg under the male equation.
pounds
- Male equation
- Female equation
| Category | Male equation | Female equation |
|---|---|---|
| 5 ft | 110.2 | 100.3 |
| 165 cm | 135.4 | 125.5 |
| 175 cm | 155.3 | 145.4 |
| 6 ft | 171.1 | 161.2 |
Male Devine is 110.2, 135.4, 155.3, and 171.1 lb.
Female Devine is 100.3, 125.5, 145.4, and 161.2 lb.
Female Devine at 165 cm is 125.5 lb. At 6 feet it is the 161.2 lb from Example 4. The displayed gap at 165 cm is 135.4 − 125.5 = 9.9 lb. Same 4.5 kg, same 9.9 lb on the rounded card, at 5 feet, at 165 cm, at 175 cm, and at 6 feet.
Example 6: under 5 feet
150 cm is 150 ÷ 2.54 = 59.055 inches, displayed as 59.1 in. That is 0.945 inch under 5 feet. The published equations start at 5 feet. The calculator still multiplies.
Male Devine: 50 + 2.3 × (59.055 − 60) = 50 − 2.173 = 47.83 kg, displayed as 105.4 lb
Female Devine: 45.5 − 2.173 = 43.33 kg, displayed as 95.5 lb
Male Robinson displays as 110 lb. Female Robinson displays as 103.9 lb.
The CDC band at 150 cm is 91.8 lb to 123.5 lb on both equations. Devine male, 105.4 lb, still lands inside it. The calculator page treats a height under 5 feet as outside the original tables, even though the arithmetic runs. Read 105.4 lb with that limit in mind.
The gap is 105.4 − 95.5 = 9.9 lb again. A negative inch count does not change the 4.5 kg difference between the bases.
Example 7: the mistake of reading Devine as the whole healthy range
At 175 cm the male Devine result is one point, 155.3 lb. The CDC band on that same card is 124.9 to 168.1 lb. The width is 43.2 lb. Devine is 30.4 lb above the bottom and 12.8 lb below the top.
A weight of 140 lb at 175 cm is inside the band and 15.3 lb under Devine. A weight of 165 lb is inside the band and 9.7 lb over Devine. The BMI post puts 70 kg (154.3 lb) at this height at BMI 22.9, which is the healthy-weight category. 154.3 is 0.9 lb under the Devine headline and well inside the band. Chasing 155.3 from 154.3 is a 0.9 lb gap on a 43.2 lb range.
The formulas also ignore a week of training. A higher weight from muscle can sit inside the CDC band and above Devine. The card has no field for that. The BMI calculator will score the weight you actually have. This one will keep returning the height equation.
Swapping the equation is a smaller, fully visible miss. At 175 cm it moves Devine by 9.9 lb, from 155.3 to 145.4. The field is 1 or 0. Check it before you compare the headline with a scale.
Example 8: where Robinson and Devine cross
Robinson starts higher at 5 feet and climbs more slowly. On the male equation the slope gap is 2.3 − 1.85 = 0.45 kg per inch. The base gap is 51.65 − 50 = 1.65 kg. They meet when 1.65 = 0.45 × inches, which is 1.65 ÷ 0.45 = 3.67 inches over 5 feet.
The table shows the cross between the rows we already have.
At 160 cm (about 3.0 inches over 5 feet) male Robinson is 126.1 lb and Devine is 125.4 lb. Robinson is still 0.7 lb higher.
At 165 cm (about 5.0 inches over) male Robinson is 134.1 lb and Devine is 135.4 lb. Devine is 1.3 lb higher.
By 175 cm the male gap is the 5.1 lb from Example 1. By 6 feet it is 171.1 − 162.8 = 8.3 lb.
The female slopes are 2.3 and 1.65, a gap of 0.65 kg per inch. The female bases are 48.67 and 45.5, a gap of 3.17 kg. They meet near 3.17 ÷ 0.65 = 4.9 inches over 5 feet. At 160 cm the card still has Robinson higher: 118.2 lb against Devine 115.5 lb. At 165 cm they are almost together: Devine 125.5 lb, Robinson 125.3 lb. At 175 cm Devine leads by 145.4 − 139.7 = 5.7 lb.
Use both lines. The headline is Devine. Robinson is the second published fit. The CDC pair is the screening range around them.
The examples next to each other
| Case | Equation | Height | Devine | Robinson | BMI low | BMI high |
|---|---|---|---|---|---|---|
| 1. Default | Male | 175 cm | 155.3 lb | 150.2 lb | 124.9 lb | 168.1 lb |
| 1. Height rounded to 69 in | Male | 69 in used early | 155.9 lb | |||
| 2. Same height | Female | 175 cm | 145.4 lb | 139.7 lb | 124.9 lb | 168.1 lb |
| 3. Exactly 5 feet | Male | 152.4 cm | 110.2 lb | 113.9 lb | 94.7 lb | 127.5 lb |
| 3. Exactly 5 feet | Female | 152.4 cm | 100.3 lb | 107.3 lb | 94.7 lb | 127.5 lb |
| 4. Exactly 6 feet | Male | 182.88 cm | 171.1 lb | 162.8 lb | 136.4 lb | 183.6 lb |
| 4. Exactly 6 feet | Female | 182.88 cm | 161.2 lb | 151 lb | 136.4 lb | 183.6 lb |
| 4. Typed as 183 cm | Male | 183 cm | 171.3 lb | 163 lb | 136.6 lb | 183.8 lb |
| 5. Step | Male | 160 cm | 125.4 lb | 126.1 lb | 104.4 lb | 140.5 lb |
| 5. Step | Male | 190 cm | 185.3 lb | 174.2 lb | 147.2 lb | 198.2 lb |
| 6. Under 5 feet | Male | 150 cm | 105.4 lb | 110 lb | 91.8 lb | 123.5 lb |
| 6. Under 5 feet | Female | 150 cm | 95.5 lb | 103.9 lb | 91.8 lb | 123.5 lb |
| 8. Just after the cross | Male | 165 cm | 135.4 lb | 134.1 lb | 111 lb | 149.5 lb |
Open the ideal body weight calculator with the equation and the height in centimetres. Read Devine, then Robinson, then the two CDC weights. For a category from the weight you already have, use the BMI calculator. The result is a published height equation. It is a poor stand-in for a personal target.