How long is heat lamp required

I have 6 egg producing chickens and got my first 4 chicks this weekend; they're a week old. How long do they need to be kept under the heat lamp?

Generally people leave their chicks in the brooder between 4 and 6 weeks, or until the chicks are nearly all feathered out. However, on warm sunny days when they're around 2 weeks old you can let them out into a secure pen during the day only.
Have you heard of alternate brooding methods, such as a heat plate or a heating pad (search Mama heating pad here on BYC)? They're a lot safer than a heat lamp and are closer to the way a mother hen broods her babies.

Ditto on the same question. Mine are I think around 2 weeks, this Wednesday will be a week since we inherited my daughters great idea to buy a chick and then had to buy another for company.

By the time your chicks are starting their third week, they should be fine without any heat lamp during the day as long as the temp is between 70-75F. At night, they'll need heat until close to the end of the fourth week, but if you've had a 250 watt bulb, you may want to swap it for a 75 or 100 watts.

I've seen that generally people tend to over-heat their chicks and keep them under artificial heat much longer than is necessary or advantageous. The heat weaning should begin halfway through the first month, and by the end of that month, the chicks should be well feathered and no longer need heat.

This is generally speaking. There are always exceptions and adjustments.

A word of caution to those who are planning on taking their chicks outside for short periods when they reach two weeks. It's just as important to protect them from over exposure to direct sunlight without providing shade as it is to protect against cold breezes. Down is a poor insulator both against excess heat as well as cold. Keep these in mind, but do let your chicks begin enjoying the great outdoors, weather permitting.

Thank you! Will check out alternate methods!