A weight loss calculator can serve a variety of purposes. The most basic type will ask for a few personal details about your age, sex, height and current weight and then calculate your Body Mass Index – a number usually between15 and 50. The ideal number is between 18.5 and 25, if you are above 25 then you need to consider losing some weight by a combination of exercise and a healthy diet. If you are bordering on 25 then it's recommended to go on a light diet or increase your exercise to shed a few pounds.

One word of warning about the BMI calculators though, they should be used as a rough guideline only. The BMI calculation is known to be somewhat inaccurate and will often judge fit and healthy athletes as being morbidly obese! Your doctor can give a more accurate assessment of your current body status and tell you how urgently you need to start losing weight.

The Internet has also given us access to a whole range of new weight loss calculators which can work out everything from a healthy weight loss rate to how much exercise you need to do to ensure you have a calorie deficit (eg. You are burning more calories than you take in so your body tries to compensate by using your body fat storage for fuel).

These calculators can help with your diet planning in all sorts of ways, from creating a work out regime to finding out if you are on course with your weight loss plan. A quick word of warning though: all the figures given are rough averages only, everyone will be different but it does give some numbers to aim for.

Weight loss calculators can cover every aspect of the weight loss cycle. For example, you use one calculator to find out how many calories your body needs to maintain your current lifestyle, then you use a BMI calculator to find out your ideal weight and then another weight loss calculator informs you that you need to be eating 300 less calories per day to get to a specific weight by a specific time. Reducing your calorie intake may not be an option, but then you can use an exercise calculator to find out how much exercise you need to do to burn up those 300 calories.

Another calculator which will comes in handy is a calorie counter where you can select the type of food you are eating and it can make rough estimate on how many calories it contains. You can even get iPhone apps where you can log all the food you eat and it tells you approximately how many calories you've eaten for the day. This is particularly useful if you need to reduce your calorie.

By using a combination of these calculators you can not only get a rough idea of how much weight you need to lose but also how many calories you need to reduce and how much exercise you need to do to speed up the weight loss process.