How this calculator works
Gravity flow relates millilitres per minute to drops per minute through the tubing drop factor. The manufacturer specifies that factor; it is not a patient characteristic. The page shows the exact arithmetic and a nearest-whole-drop value, without feeding the rounded value back into other results. Monitoring and any pump programming require clinical checks. The result is an estimate for information only and is not medical advice.
Formula
Drops/min = volume(mL) x drop factor(drops/mL)/time(min). mL/h = 60 x volume/time. Rearranging solves any one of volume, time or factor from the remaining values.
Worked example
For 1000 mL over 8 hours with 20 drops/mL tubing, flow is 1000 x 20/480 = 41.6667 drops/min, nearest whole value 42, and 125 mL/h.
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Frequently asked questions
Where do I find the drop factor?
Read the tubing packaging or manufacturer documentation. Do not assume a factor from the fluid type.
Does this recommend a clinical rate?
No. Enter the volume and duration already prescribed and verify the result within the applicable clinical workflow.
Why are exact and rounded drop rates both shown?
A gravity drip is counted in discrete drops. Rounding changes delivered flow slightly and needs clinical judgement.