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


 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 (>97th percentile or <3rd 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
  1. 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% 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.

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