Basic laboratory thermometer. Easy to read with both Fahrenheit and Celsius.
Chicks require an area of space that has a temperature of 90-95 degrees. They also need to get away from the heat if they get too hot. The coolest area of your brooder should be no less then 70 degrees.
Usually a 250 watt heat lamp per 25 birds is required to start with. Hang your heat light 24 inches off the ground in the center of your brooding area. Check the temperature at the bird level with a thermometer. This will tell you if you need to provide more heat or raise your heat source to lower your temperature.
As your chicks grow, you will need to lower your brooding temperature, Decrease your temperature by 5 degrees per week until your whole brooding area is 70 degrees. Then maintain your temperature until your birds are fully feathered.
Remember, watch your birds. If they are huddling together, they are probably too cold. If they are away from the heat as far as they can get, they are too hot. Chicks all in a corner suggests that you may have a draft. Chicks spread around and drinking and eating happily are just right.
Start warming your brooder pen at least two days before birds arrive. Check your temperature regularly once chicks have arrived.