How it works
The calculator derives pre-pregnancy BMI and applies separate total-gain ranges for singleton and twin pregnancies. It also estimates a broad week-specific interval.
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
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?unitSystem=UnitsChoice · Required · Default: imperial · Accepted values: imperial, metric
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?pregnancyType=Pregnancy typeChoice · Required · Default: singleton · Accepted values: singleton, twins
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?gestationalWeek=Current gestational weekNumber · Required · Default: 20
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?preWeightKg=Pre-pregnancy weightNumber · Required · Default: 64 · Used when unitSystem = metric
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?currentWeightKg=Current weightNumber · Required · Default: 69 · Used when unitSystem = metric
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?heightCm=HeightNumber · Required · Default: 165 · Used when unitSystem = metric
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?preWeightLb=Pre-pregnancy weightNumber · Required · Default: 141 · Used when unitSystem = imperial
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?currentWeightLb=Current weightNumber · Required · Default: 152 · Used when unitSystem = imperial
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?feet=Height feetNumber · Required · Default: 5 · Used when unitSystem = imperial
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?inches=Height inchesNumber · Required · Default: 5 · Used when unitSystem = imperial
Outputs
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currentGainCurrent weight gainText · Primary output
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expectedByWeekReference gain by current weekText
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totalRangeReference total gainText
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statusComparisonText
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prePregnancyBmiPre-pregnancy BMINumber
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bmiCategoryPre-pregnancy BMI categoryText
Prenatal context
Weight change during pregnancy has many causes. The comparison is educational and should be interpreted with prenatal-care guidance rather than used as a stand-alone target.