Amit, have you come across the idea of your Basal Metabolic Rate (BMR)? Your BMR is the bare minimum daily calorie intake that you need - metabolic "fuel" for your liver, brain, heart, etc - it takes no account of physical activity.

The are lots of BMR calculators on the Web - they are probably accurate to +/- 10% or so. One of those, combined with a site like the one that Dave has provided, will let you match your daily calorie intake to your BMR - if your daily calorie intake is less than your BMR you will lose weight - I would aim for losing no more than 1 kg/week - more than that will probably not be sustainable.

The idea of mindful eating might also help. Essentially that means eating slowly, taking time to notice the flavours and textures of your food. Mindful eating leads to satiety (feeling full) after eating a sensible amount of food but eating quickly means you will probably eat too much before you feel full.