Calculator: WHO infant weight for age percentiles (<24 months)

Input

Sex	Female
	Male
Age
Weight

Results

Important: Inputs must be complete to perform calculation.


Z-score
Percentile

Decimal precision

Notes

Weight percentiles are best interpreted with reference to height (refer to the calculator for infant weight for length percentiles).
At the extremes (>97^th percentile or <3^rd percentile), small differences in percentiles represent clinically important differences. At these extremes, the Z-score is a more precise reflection of how far the measurement deviates from the mean and is a useful tool for tracking changes.
The accuracy of the calculation can be assessed by viewing the graph of weight-for-age percentiles for this sex and age group in UpToDate.
For all LMS tables, the row in the table corresponding to the patient-specific value is found in the first column of the table; values to be used for L (the Box-Cox power), M (the median), and S (the generalized coefficient of variation) in the equation for Z-score are retrieved.
Z-scores may be used to do a table lookup for the corresponding percentile in the Normal table percentiles for Z-score table (below). Numbers along the left side (Y-axis) of the table represent the first number and first decimal place of the Z-score, while the numbers along the top (X-axis) of the table represent the second decimal position of the Z-score.
WHO: World Health Organization.

Equations used

Z-score = ((Weight/M)^L - 1) / (L * S)

Percentile = ZtoPercentile(Z-score)

References

World Health Organization. The WHO Child Growth Standards. Available at: www.who.int/childgrowth/standards/en/ (Accessed on March 4, 2019).

LMS table: Weight-for-age percentiles, girls 0 to 24 months, WHO growth standards

Age [months]	Power [L]	Median [M]	Variation [S]
0	0.3809	3.2322	0.14171
1	0.1714	4.1873	0.13724
2	0.0962	5.1282	0.13000
3	0.0402	5.8458	0.12619
4	-0.0050	6.4237	0.12402
5	-0.0430	6.8985	0.12274
6	-0.0756	7.2970	0.12204
7	-0.1039	7.6422	0.12178
8	-0.1288	7.9487	0.12181
9	-0.1507	8.2254	0.12199
10	-0.1700	8.4800	0.12223
11	-0.1872	8.7192	0.12247
12	-0.2024	8.9481	0.12268
13	-0.2158	9.1699	0.12283
14	-0.2278	9.3870	0.12294
15	-0.2384	9.6008	0.12299
16	-0.2478	9.8124	0.12303
17	-0.2562	10.0226	0.12306
18	-0.2637	10.2315	0.12309
19	-0.2703	10.4393	0.12315
20	-0.2762	10.6464	0.12323
21	-0.2815	10.8534	0.12335
22	-0.2862	11.0608	0.12350
23	-0.2903	11.2688	0.12369
24	-0.2941	11.4775	0.12390

LMS table: Weight-for-age percentiles, boys 0 to 24 months, WHO growth standards

Age [months]	Power [L]	Median [M]	Variation [S]
0	0.3487	3.3464	0.14602
1	0.2297	4.4709	0.13395
2	0.1970	5.5675	0.12385
3	0.1738	6.3762	0.11727
4	0.1553	7.0023	0.11316
5	0.1395	7.5105	0.11080
6	0.1257	7.9340	0.10958
7	0.1134	8.2970	0.10902
8	0.1021	8.6151	0.10882
9	0.0917	8.9014	0.10881
10	0.0820	9.1649	0.10891
11	0.0730	9.4122	0.10906
12	0.0644	9.6479	0.10925
13	0.0563	9.8749	0.10949
14	0.0487	10.0953	0.10976
15	0.0413	10.3108	0.11007
16	0.0343	10.5228	0.11041
17	0.0275	10.7319	0.11079
18	0.0211	10.9385	0.11119
19	0.0148	11.1430	0.11164
20	0.0087	11.3462	0.11211
21	0.0029	11.5486	0.11261
22	-0.0028	11.7504	0.11314
23	-0.0083	11.9514	0.11369
24	-0.0137	12.1515	0.11426

LMS table: Normal table percentiles for Z-score

Z	0	1	2	3	4	5	6	7	8	9
-3.0	0.13%	0.13%	0.13%	0.12%	0.12%	0.11%	0.11%	0.11%	0.10%	0.10%
-2.9	0.19%	0.18%	0.18%	0.17%	0.16%	0.16%	0.15%	0.15%	0.14%	0.14%
-2.8	0.26%	0.25%	0.24%	0.23%	0.23%	0.22%	0.21%	0.21%	0.20%	0.19%
-2.7	0.35%	0.34%	0.33%	0.32%	0.31%	0.30%	0.29%	0.28%	0.27%	0.26%
-2.6	0.47%	0.45%	0.44%	0.43%	0.41%	0.40%	0.39%	0.38%	0.37%	0.36%
-2.5	0.62%	0.60%	0.59%	0.57%	0.55%	0.54%	0.52%	0.51%	0.49%	0.48%
-2.4	0.82%	0.80%	0.78%	0.75%	0.73%	0.71%	0.70%	0.68%	0.66%	0.64%
-2.3	1.07%	1.04%	1.02%	0.99%	0.96%	0.94%	0.91%	0.89%	0.87%	0.84%
-2.2	1.39%	1.36%	1.32%	1.29%	1.26%	1.22%	1.19%	1.16%	1.13%	1.10%
-2.1	1.79%	1.74%	1.70%	1.66%	1.62%	1.58%	1.54%	1.50%	1.46%	1.43%
-2.0	2.28%	2.22%	2.17%	2.12%	2.07%	2.02%	1.97%	1.92%	1.88%	1.83%
-1.9	2.87%	2.81%	2.74%	2.68%	2.62%	2.56%	2.50%	2.44%	2.39%	2.33%
-1.8	3.59%	3.52%	3.44%	3.36%	3.29%	3.22%	3.14%	3.07%	3.01%	2.94%
-1.7	4.46%	4.36%	4.27%	4.18%	4.09%	4.01%	3.92%	3.84%	3.75%	3.67%
-1.6	5.48%	5.37%	5.26%	5.16%	5.05%	4.95%	4.85%	4.75%	4.65%	4.55%
-1.5	6.68%	6.55%	6.43%	6.30%	6.18%	6.06%	5.94%	5.82%	5.71%	5.59%
-1.4	8.08%	7.93%	7.78%	7.64%	7.49%	7.35%	7.22%	7.08%	6.94%	6.81%
-1.3	9.68%	9.51%	9.34%	9.18%	9.01%	8.85%	8.69%	8.53%	8.38%	8.23%
-1.2	11.51%	11.31%	11.12%	10.94%	10.75%	10.57%	10.38%	10.20%	10.03%	9.85%
-1.1	13.57%	13.35%	13.14%	12.92%	12.71%	12.51%	12.30%	12.10%	11.90%	11.70%
-1.0	15.87%	15.63%	15.39%	15.15%	14.92%	14.69%	14.46%	14.23%	14.01%	13.79%
-0.9	18.41%	18.14%	17.88%	17.62%	17.36%	17.11%	16.85%	16.60%	16.35%	16.11%
-0.8	21.19%	20.90%	20.61%	20.33%	20.05%	19.77%	19.49%	19.22%	18.94%	18.67%
-0.7	24.20%	23.89%	23.58%	23.27%	22.97%	22.66%	22.36%	22.07%	21.77%	21.48%
-0.6	27.43%	27.09%	26.76%	26.44%	26.11%	25.79%	25.46%	25.14%	24.83%	24.51%
-0.5	30.85%	30.50%	30.15%	29.81%	29.46%	29.12%	28.77%	28.43%	28.10%	27.76%
-0.4	34.46%	34.09%	33.72%	33.36%	33.00%	32.64%	32.28%	31.92%	31.56%	31.21%
-0.3	38.21%	37.83%	37.45%	37.07%	36.69%	36.32%	35.94%	35.57%	35.20%	34.83%
-0.2	42.07%	41.68%	41.29%	40.91%	40.52%	40.13%	39.74%	39.36%	38.97%	38.59%
-0.1	46.02%	45.62%	45.22%	44.83%	44.43%	44.04%	43.64%	43.25%	42.86%	42.47%
-0.0	50.00%	49.60%	49.20%	48.80%	48.40%	48.01%	47.61%	47.21%	46.81%	46.41%
0.0	50.00%	50.40%	50.80%	51.20%	51.60%	51.99%	52.39%	52.79%	53.19%	53.59%
0.1	53.98%	54.38%	54.78%	55.17%	55.57%	55.96%	56.36%	56.75%	57.14%	57.54%
0.2	57.93%	58.32%	58.71%	59.10%	59.48%	59.87%	60.26%	60.64%	61.03%	61.41%
0.3	61.79%	62.17%	62.55%	62.93%	63.31%	63.68%	64.06%	64.43%	64.80%	65.17%
0.4	65.54%	65.91%	66.28%	66.64%	67.00%	67.36%	67.72%	68.08%	68.44%	68.79%
0.5	69.15%	69.50%	69.85%	70.19%	70.54%	70.88%	71.23%	71.57%	71.90%	72.24%
0.6	72.58%	72.91%	73.24%	73.57%	73.89%	74.22%	74.54%	74.86%	75.18%	75.49%
0.7	75.80%	76.12%	76.42%	76.73%	77.04%	77.34%	77.64%	77.94%	78.23%	78.52%
0.8	78.81%	79.10%	79.39%	79.67%	79.96%	80.23%	80.51%	80.79%	81.06%	81.33%
0.9	81.59%	81.86%	82.12%	82.38%	82.64%	82.89%	83.15%	83.40%	83.65%	83.89%
1.0	84.13%	84.38%	84.61%	84.85%	85.08%	85.31%	85.54%	85.77%	85.99%	86.21%
1.1	86.43%	86.65%	86.86%	87.08%	87.29%	87.49%	87.70%	87.90%	88.10%	88.30%
1.2	88.49%	88.69%	88.88%	89.07%	89.25%	89.44%	89.62%	89.80%	89.97%	90.15%
1.3	90.32%	90.49%	90.66%	90.82%	90.99%	91.15%	91.31%	91.47%	91.62%	91.77%
1.4	91.92%	92.07%	92.22%	92.36%	92.51%	92.65%	92.79%	92.92%	93.06%	93.19%
1.5	93.32%	93.45%	93.57%	93.70%	93.82%	93.94%	94.06%	94.18%	94.30%	94.41%
1.6	94.52%	94.63%	94.74%	94.85%	94.95%	95.05%	95.15%	95.25%	95.35%	95.45%
1.7	95.54%	95.64%	95.73%	95.82%	95.91%	95.99%	96.08%	96.16%	96.25%	96.33%
1.8	96.41%	96.49%	96.56%	96.64%	96.71%	96.78%	96.86%	96.93%	97.00%	97.06%
1.9	97.13%	97.19%	97.26%	97.32%	97.38%	97.44%	97.50%	97.56%	97.62%	97.67%
2.0	97.73%	97.78%	97.83%	97.88%	97.93%	97.98%	98.03%	98.08%	98.12%	98.17%
2.1	98.21%	98.26%	98.30%	98.34%	98.38%	98.42%	98.46%	98.50%	98.54%	98.57%
2.2	98.61%	98.65%	98.68%	98.71%	98.75%	98.78%	98.81%	98.84%	98.87%	98.90%
2.3	98.93%	98.96%	98.98%	99.01%	99.04%	99.06%	99.09%	99.11%	99.13%	99.16%
2.4	99.18%	99.20%	99.22%	99.25%	99.27%	99.29%	99.31%	99.32%	99.34%	99.36%
2.5	99.38%	99.40%	99.41%	99.43%	99.45%	99.46%	99.48%	99.49%	99.51%	99.52%
2.6	99.53%	99.55%	99.56%	99.57%	99.59%	99.60%	99.61%	99.62%	99.63%	99.64%
2.7	99.65%	99.66%	99.67%	99.68%	99.69%	99.70%	99.71%	99.72%	99.73%	99.74%
2.8	99.74%	99.75%	99.76%	99.77%	99.77%	99.78%	99.79%	99.80%	99.80%	99.81%
2.9	99.81%	99.82%	99.83%	99.83%	99.84%	99.84%	99.85%	99.85%	99.86%	99.86%
3.0	99.87%	99.87%	99.87%	99.88%	99.88%	99.89%	99.89%	99.89%	99.90%	99.90%

Only digits 0 to 9 and a single decimal point (".") are acceptable as numeric inputs. Attempted input of other characters into a numeric field may lead to an incorrect result.

Information on this page may not appear correctly if printed.

All information contained in and produced by the EBMcalc system is provided for educational purposes only. This information should not be used for the diagnosis or treatment of any health problem or disease. THIS INFORMATION IS NOT INTENDED TO REPLACE CLINICAL JUDGMENT OR GUIDE INDIVIDUAL PATIENT CARE IN ANY MANNER. Click here for full notice and disclaimer.

Topic 15632 Version 12.0

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Calculator: WHO infant weight for age percentiles (<24 months)