How to use this calculator
- Enter or choose volume to infuse.
- Enter or choose infusion time: hours.
- Enter or choose infusion time: minutes.
- Enter or choose drop factor of the giving set.
- The drip rate (rounded) updates as you type. Use Copy result or Share to keep it.
Method
Drops per minute = Volume (mL) × Drop factor (gtt/mL) ÷ Time (min); Flow rate (mL/h) = Volume ÷ Time (h)
- Volume
- fluid to be infused, in mL
- Drop factor
- drops that make 1 mL for this giving set
- Time
- prescribed infusion time
Worked example
- Time = 8 h × 60 = 480 minutes.
- Drops per minute = 1,000 × 15 ÷ 480 = 31.25, about 31 gtt/min.
- Flow rate = 1,000 ÷ 8 = 125 mL/h.
1,000 mL over 8 hours through a 15 gtt/mL set runs at about 31 drops per minute (125 mL/h).
What the result means
Count drops in the drip chamber for a full minute (or 15 seconds × 4) and adjust the roller clamp to match. Recheck regularly: gravity rates drift as the bag empties or the patient moves.
Assumptions and limits
- The drop factor is the one printed on the giving set in use.
- The infusion runs at a constant rate for the whole time.
- Gravity drip rates are approximate; use an infusion pump where precise delivery is required.
- The result is only as correct as the prescribed volume and time; it does not check the order.
Questions
What drop factor should I use?
Read it from the giving-set packaging. Macro-drip sets are typically 10–20 gtt/mL; micro-drip sets are 60 gtt/mL, where gtt/min equals mL/h.
Why round to whole drops?
Drops can only be counted whole, so the practical rate is the nearest whole number; the unrounded value is shown too.
Sources
Please note: This is a general screening estimate for adults, not medical advice or a diagnosis. Talk to a qualified health professional about your health.