How many drip emitters can I put on a mainline?
Know your flow
You can add as many drip emitters as your flow rate will support. A typical hose bibb delivers 240 gallons per hour. So you have 240 gallons available for your emitters to consume. Simply add up the total number of gallons to be consumed by the emitters that you plan to add. You can put 240 1 gallon-per-hour emitters on the line (or 480 1/2 gallon-per-hour emitters or 120 2 gallon-per-hour emitters).
Keep in mind that when adding adjustable emitters and micro sprays the output can be in excess of 30 gallons per hour. It doesnt take many sprays to use up those 240 gallons.
If you plan to add the maximum allowable emitters to your drip tubing, consider using pressure compensating emitters as they will maintain the same flow rate within a range of pressure (psi) and elevation changes. Non-pressure compensating emitters will output more or less water with changes in pressure or elevation. You may run out of water for emitters at the end of the line in this case.
More information on Drip Emitters & Drip Main Line Tubing
Choosing the right drip emitter
Compare all drip emitters
Drip Tubing Maximum Run Chart (PDF)
Drip Irrigation Basics & Installation