ORS Volume Calculator for Children (WHO Plan B)
Weight-based oral rehydration salts dosing for children — 75 mL/kg/dose · over 4 hours, in small frequent sips (spoon or cup). Enter age and weight for the volume in mL.
Pediatric dosing
Some dehydration — WHO Plan B (first 4 hours)
Replacing ongoing losses (after each loose stool)
Oral rehydration salts (ORS) dose chart by age and weight
Some dehydration — WHO Plan B (first 4 hours). Weights are WHO/IAP reference medians for age — always dose on the measured weight.
| Age | Weight | Dose (mL) | ORS solution (WHO low-osmolarity, reconstituted) | Frequency |
|---|---|---|---|---|
| 15 days | 3.8 kg | 285 mL | 285 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 1 month | 4.3 kg | 322.5 mL | 325 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 3 months | 6.1 kg | 457.5 mL | 460 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 6 months | 7.6 kg | 570 mL | 570 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 9 months | 8.6 kg | 645 mL | 645 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 1 year | 9.3 kg | 697.5 mL | 700 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 18 months | 10.6 kg | 795 mL | 795 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 2 years | 11.8 kg | 885 mL | 885 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 3 years | 14.1 kg | 1057.5 mL | 1060 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 4 years | 16.2 kg | 1215 mL | 1215 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 5 years | 17.5 kg | 1312.5 mL | 1315 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 6 years | 19 kg | 1425 mL | 1425 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 8 years | 24.4 kg | 1830 mL | 1830 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 10 years | 31.1 kg | 2332.5 mL | 2335 mL | Over 4 hours, in small frequent sips (spoon or cup) |
| 12 years | 39.4 kg | 2955 mL | 2955 mL | Over 4 hours, in small frequent sips (spoon or cup) |
Strengths in the calculator
- ORS solution (WHO low-osmolarity, reconstituted) (Oral) — Dissolve each sachet in exactly the volume printed on the pack (usually 1 litre; some 200 mL). Use within 24 hours.
Different strength on your bottle? Use “Different strength on the bottle?” under the result.
Safety
Contraindications and cautions
- Severe dehydration or shock, paralytic ileus, persistent vomiting — use IV fluids.
Pregnancy and breastfeeding
Legacy FDA category A. Safe in pregnancy.
Safe; continue breastfeeding throughout diarrhoea.
Clinical notes
Cornerstone of diarrhoea treatment. Give zinc for 10–14 days in children. Continue feeding; antibiotics only for dysentery, cholera or other specific indications.
Adult and adolescent (≥40 kg) dose
.
Replace estimated deficit plus 200–400 mL after each loose stool; drink as much as wanted.
Other names and brands
Also known as ORS, WHO low-osmolarity ORS, Oral rehydration solution.
- India: Electral
Brand examples only — products and strengths vary by country. Always check the label.
Frequently asked questions
What is the oral rehydration salts dose for children?
Some dehydration — WHO Plan B (first 4 hours): 75 mL/kg/dose · over 4 hours, in small frequent sips (spoon or cup). Usual duration: Reassess at 4 hours. Always use the child's measured weight and check the strength on the bottle.
How many mL of ORS solution (WHO low-osmolarity, reconstituted) for an 11.8 kg child?
For some dehydration — WHO Plan B (first 4 hours), an 11.8 kg child (about 2 years) needs 885 mL per dose — 885 mL of ORS solution (WHO low-osmolarity, reconstituted), over 4 hours, in small frequent sips (spoon or cup). Recalculate with the child's actual weight.
From what age can oral rehydration salts be given?
Age range in PediaRx: Birth – adult. Each indication can have its own age and weight limits, shown with its regimen.
Is oral rehydration salts safe in pregnancy?
Legacy FDA category A. Safe in pregnancy.
Sources and editorial process
- The treatment of diarrhoea: a manual for physicians and other senior health workers (2005) — World Health Organization
- ESPGHAN/ESPID evidence-based guidelines for acute gastroenteritis in children in Europe (Guarino et al., JPGN 2014) — ESPGHAN / ESPID
Dosing data last updated 2026-09-27. PediaRx is built and maintained by Dr. Shounak Pal, MBBS (Medical Officer, Government of West Bengal, India — founder and developer of PediaRx). Every regimen is encoded with explicit units, maximum doses and age/weight limits and is checked by automated tests before publication. Report an error: hello@pediarx.com.
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Clinical disclaimer: reference tool for qualified health professionals. Verify every dose against current guidance and the product label before prescribing.
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