Drops to mL Conversion Calculator NZ

This calculator converts between drops (gtt) and millilitres in either direction, using whatever drop factor matches your dropper, medicine bottle, or IV giving set. A drop is not a fixed unit of volume, since its size depends on the liquid's viscosity and the width of the dropper tip, so you first choose a drop factor: the standard 20 drops per mL used for most medicine and eye droppers, an IV macrodrip rate of 15 or 10 gtt/mL, a microdrip or paediatric rate of 60 gtt/mL, or your own custom figure if the packaging states something different. Next you pick a direction, either drops to millilitres or millilitres to drops, and enter the number of drops or the volume you are converting. The calculator returns the equivalent drops, millilitres, and drop factor used, plus a breakdown of your conversion and a table of common conversions at that factor, from 1 through to 100 drops. Use it to check a dose, work out how much liquid a set number of drops makes up, or convert a volume into drops for a dropper or IV set. Because drop size varies between liquids and equipment, always confirm the exact drop factor printed on the packaging or giving set label rather than assuming one universal rate, and for medicine dosed in drops, follow your pharmacist's or doctor's instructions rather than a generic conversion.

How Drops to mL Conversion Works

A drop is not a fixed unit of volume. Unlike millilitres, teaspoons, or litres, the size of a drop depends on the liquid's viscosity and surface tension and on the size of the opening it falls from. To convert drops to millilitres, you need a drop factor: the number of drops that make up one millilitre for that specific dropper or liquid. The formula is straightforward once you know the drop factor.

Common Drop Factors

Use	Drop Factor	1 mL equals
Standard medicine or eye dropper	20 gtt/mL	20 drops
IV macrodrip set (common)	15 gtt/mL	15 drops
IV macrodrip set (wide bore)	10 gtt/mL	10 drops
IV microdrip / paediatric set	60 gtt/mL	60 drops

Use

Drop Factor

1 mL equals

Standard medicine or eye dropper

20 gtt/mL

20 drops

IV macrodrip set (common)

15 gtt/mL

15 drops

IV macrodrip set (wide bore)

10 gtt/mL

10 drops

IV microdrip / paediatric set

60 gtt/mL

60 drops

The 20 drops per mL figure is the most widely used general reference for water-based liquids like saline nasal spray, eye drops, and many liquid medicines. IV giving sets are labelled with their own drop factor by the manufacturer, and this is what nurses use to calculate drip rates. Always check the packaging or prescribing information rather than assuming a single universal rate, since thicker liquids form larger drops and therefore fewer drops per millilitre.

Why This Matters

Getting the drop factor wrong can lead to dosing errors, particularly with medicines where drops are used to measure small, precise amounts (such as paediatric medicine, eye drops, or concentrated liquid supplements). If a medicine label specifies a dose in drops rather than mL, use the drop factor stated on that specific product's packaging or accompanying leaflet, not a generic assumption. This calculator is a reference tool for general conversion and does not replace instructions from a pharmacist, doctor, or product label.

Related Calculators

Essential Calculators: unit converters and everyday tools.

mL to Grams Calculator: convert volume to mass by density.

Ounces to Millilitres Converter: fluid ounces to mL.

Cooking Measurement Converter: teaspoons, tablespoons, cups and mL.

Unit Converter: general length, volume, weight and more.

Sources: Standard pharmacy drop factor conventions (20 gtt/mL for medicine droppers). IV administration set drop factors as commonly published by New Zealand district health board medicines information services and manufacturer packaging (10, 15, 20, and 60 gtt/mL sets).

This calculator provides a general reference conversion only. Actual drop size varies by liquid and dropper. For any medicine dosed in drops, always follow the drop factor and instructions on the product packaging or from your pharmacist or doctor, not a generic conversion.

Frequently asked questions

How many drops are in 1 mL?

It depends on the dropper or drip set. The most common standard used for liquid medicine and eye drops is 20 drops per millilitre. Standard IV administration sets are labelled with their own drop factor, typically 10, 15, 20, or 60 drops per mL (macrodrip sets are 10 to 20 gtt/mL, microdrip or paediatric sets are 60 gtt/mL). Always check the packaging or giving set for the exact drop factor, since droplet size varies with liquid viscosity, surface tension, and the dropper tip opening.

Why do drop sizes vary between liquids?

Drop size depends on the liquid's viscosity and surface tension and on the diameter of the dropper tip or nozzle. Water-based liquids like eye drops or saline typically form drops close to 20 per mL with a standard dropper tip. Thicker or oilier liquids (such as some oral suspensions or essential oils) often form larger drops, meaning fewer drops make up a millilitre. This is why pharmacists and nurses use the specific drop factor printed on the medicine bottle or IV set rather than assuming 20 drops per mL for every liquid.

What is a drop factor in an IV drip?

A drop factor is the number of drops a specific IV giving set delivers per millilitre of fluid, printed on the packaging (for example 15 gtt/mL or 20 gtt/mL for macrodrip sets, and 60 gtt/mL for microdrip or paediatric sets). It is used with the prescribed flow rate to calculate the drip rate in drops per minute. This calculator converts between drops and millilitres using whatever drop factor you select, but it does not calculate infusion drip rates over time.

If you've found a bug, or would like to contact us, or learn more about James Graham and Calculate.co.nz.

Calculate.co.nz is partnered with Interest.co.nz for New Zealand's highest quality calculators and financial analysis.

Calculate.co.nz is the sister site of CalculatorHub.com, the world's largest calculator website by tool count.

All calculators and tools are provided for educational and indicative purposes only and do not constitute financial advice.

Calculate.co.nz is proudly part of the Realtor.co.nz group, New Zealand's leading property transaction literacy platform, helping Kiwis understand the home buying and selling process from start to finish. Whether you're a first home buyer navigating your first property purchase, an investor evaluating your next acquisition, or a homeowner planning to sell, Realtor.co.nz provides clear, independent, and trustworthy guidance on every step of the New Zealand property transaction journey.

Calculate.co.nz is also partnered with Premium Homes to promote informed choices that lead to better long-term outcomes for Kiwi households.

Calculate.co.nz is hosted in Auckland by SiteHost New Zealand.

All content on this website, including calculators, tools, source code, and design, is protected under the Copyright Act 1994 (New Zealand). No part of this site may be reproduced, copied, distributed, stored, or used in any form without prior written permission from the owner.

About & trust: Why Calculate is NZ's most comprehensive · By the Numbers · How we compare · Editorial standards · How we keep data current · NZ finance glossary · Research & data · Financial literacy NZ · About · Free API · Privacy policy · Terms of use

Reviewed and maintained. Last reviewed 2026-08-15 and checked on a twice-monthly cycle against IRD, RBNZ and Stats NZ. How we keep data current.

Drops to mL Conversion Calculator NZ

1. Drop Factor

2. Convert

Conversion Result

Common Conversions at This Drop Factor

Your Conversion

Reference Drop Factors