BMI Calculator – Know Your Healthy Weight
Check your Body Mass Index (BMI) instantly with HealthHero’s free Irish BMI Calculator. See if you are underweight, a healthy weight, overweight, or obese and know your next steps.
Our tool follows HSE standards and Irish BMI guidelines, giving you a clear picture of your health. If you need more support, HealthHero GPs are ready with personalised advice, practical plans and expert guidance.
Body Mass Index (BMI) Calculator
How to use our online BMI calculator for Ireland
Using our Irish BMI calculator is simple.
- Enter your height in metres or centimetres.
- Enter your weight in kilograms.
- Click calculate.
In seconds, you’ll see your BMI score and which category you fall into.
This tool is free to use, works on any device and is designed to make checking your BMI quick and easy, wherever you are.
What is BMI (Body Mass Index)?
BMI = weight (kg) ÷ height (m²)
BMI stands for body mass index. It’s a simple way to estimate whether your weight is in a healthy range for your height, using your weight in kilograms and your height in metres.
Although widely used both in Ireland and globally, it's crucial to acknowledge that BMI does not directly measure body fat percentage, nor does it differentiate between muscle and fat mass. Consequently, BMI should be seen primarily as a preliminary screening tool rather than a full diagnostic measure.
Common misconceptions include assuming a high BMI always means poor health. In reality, muscle mass, bone density and individual health conditions all impact your result.
For a complete and accurate health assessment, additional evaluations, such as detailed body composition analyses and clinical examinations are highly recommended.
If you're looking for a digital option, a body mass index calculator is available here online to simplify the process. If you’re looking for age-specific tools, try a BMI calculator by age to reflect more personalised health insights.
How to Calculate BMI?
Learning how to calculate BMI is simple. To begin, input your weight in kilograms and your height in metres. This calculation will determine your body mass index, which is used to evaluate your weight category.
This simple and accurate BMI calculator lets you check your score in just a few seconds.
For instance, if you weigh 70 kg and are 1.75 m tall, your result will be a BMI of 22.9, placing you in the normal BMI range.
70 kg / (1.75 m)² = 22.9 (Normal BMI Range)
Our BMI calculator kg format ensures results are easy to interpret for users familiar with the metric system.
BMI categories explained
Understanding your BMI category helps you manage your health effectively, set clear goals, and plan lifestyle adjustments. Whether you want to calculate your BMI for personal health tracking, or use your BMI results to talk with a GP, this body mass index calculator gives you fast, reliable data you can use.
Here's a clear breakdown of BMI categories:
- Risks: nutritional deficiencies, reduced muscle mass, lower bone density, weakened immunity.
- Recommendations: Seek guidance from a nutritionist or healthcare provider for tailored nutritional plans and lifestyle adjustments.
- Benefits: Lower risk of chronic conditions such as heart disease, diabetes, hypertension.
- Recommendations: Maintain balanced nutrition, regular physical activity and your usual routine health monitoring.
- Risks: Increased risk for type 2 diabetes, cardiovascular diseases, certain cancers.
- Recommendations: Regular medical screenings, dietary support from a clinical nutritionist.
Increased physical activity, healthier lifestyle habits.
If your BMI falls within this range, it’s a good time to speak with a GP about a sustainable weight management plan.
- Risks: Significant risk of heart disease, diabetes, stroke, hypertension, joint problems, psychological impacts such as depression, anxiety, low self-esteem.
- Recommendations: Comprehensive medical treatment, structured weight-management programmes, psychological counselling, improved diet, consistent exercise, behavioural therapies.
For anyone with a BMI above 30, a comprehensive medical weight management plan with your GP’s support is strongly recommended.
Adult BMI Chart
Use this chart to quickly identify your BMI category and understand associated health implications.
This chart follows BMI standards from the HSE and WHO, reflecting recognised guidance in Ireland and worldwide.
Adult BMI Chart (Aligned with HSE and WHO Guidelines)
Below 18.5 – Underweight
Nutritional deficiencies, weakened immunity, osteoporosis and anaemia
18.5–24.9 – Normal Weight
Lower risk of cardiovascular conditions, diabetes and hypertension
25–29.9 – Overweight
Increased likelihood of diabetes, cardiovascular diseases and hypertension
30–34.9 – Obesity Class I (Moderate)
Raised risk of diabetes, heart disease and joint problems
35–39.9 – Obesity Class II (Severe)
High risk of heart disease, stroke and mobility issues
40 and above – Obesity Class III (Very Severe)
Very high risk of serious conditions including diabetes, stroke, joint issues and various cancers
Obese (BMI 30 and Above)
A BMI of 30 or higher falls into the obese category, which is further subdivided into three classes:
- Class I Obesity: BMI 30-34.9
- Class II Obesity: BMI 35-39.9
- Class III Obesity: BMI 40 and above (formerly called “morbid obesity”)
A healthy weight for your height
Your BMI result shows if your weight is in a healthy range for your height. This body mass index calculator helps you understand if you’re at a healthy weight for height and gives you a clear sign if there’s anything you need to pay attention to with your health.
When you know your healthy weight for height, you can make better choices and you can make informed choices and take control of your health.. This is a straightforward starting point for any changes you want to make.
No guessing, just facts.
Checklist: What to do with your result
- Check your healthy weight for your height
- Use your BMI to guide your eating and activity habits
- Choose a health goal to work towards
- Book a check-up or chat with a GP if you need advice
- Monitor your weight and come back to this calculator for a quick check any time
Looking at your height-to-weight ratio can help you spot risks early. This information makes it easier to plan small, realistic changes that last and support your health for the long term.
Track your BMI regularly using this free tool and check back any time you want to see your progress.
Why it’s helpful to track BMI regularly
Checking your BMI from time to time helps you notice changes early, making it easier to look after your health in the long run. Ongoing monitoring helps you see progress, set realistic goals and spot any issues before they become a bigger problem.
Plus, tracking your BMI regularly also supports weight management and helps you stay motivated on your wellness journey.
Online GP consultations for BMI concerns
Should your BMI calculation highlight health concerns, HealthHero’s expert GPs offer accessible, personalised online consultations. Easily connect with experienced healthcare professionals who provide tailored advice, specialist referrals and further medical assessments.
Schedule your consultation or explore HealthHero’s extensive weight management programmes designed specifically to meet your personal health needs and objectives.
Our online platform ensures quick, practical and effective healthcare support, conveniently accessible from your sofa. If you're concerned about your BMI, book a GP consultation today.
For more detailed medical guidance, refer to reputable sources like the HSE BMI guide or the World Health Organization’s BMI standards.
Frequently Asked Questions
Return to this simple and accurate BMI calculator whenever you want an update. Regular monitoring is especially useful if you're on a fitness programme or managing a health condition. Track your BMI over time to stay motivated and informed.
Yes. A BMI between 25 and 29.9 falls into the overweight category. If you're wondering, ‘am I overweight?’ this calculator provides a quick answer. Speak to your GP for further evaluation and advice on safe, sustainable lifestyle changes if needed.
A healthy bmi generally ranges from 18.5 to 24.9 for most adults. However, factors such as age, muscle mass, and overall health must be considered. What’s healthy for one person may not be for another, which is why it's important to interpret your bmi scale result in context with a healthcare professional.
For most people, checking your BMI every few months is enough. If you’re actively making changes to your weight or lifestyle, you might want to check more regularly. If you’re unsure, ask your GP for advice.
If your BMI is above the healthy range, start by talking to a GP or a healthcare professional. They can help you come up with a safe plan for losing weight and improving your health.