How To Calibrate Your Sprayer


In order to make sure you apply the proper amount of pesticide according to label directions for a broadcast application you must calibrate your sprayer.  Most pesticide labels will give the rates of material in gallons of water per 1,000 sq. ft.  The problem is that most people do not know how much water they are applying per 1,000 sq. ft. due to several factors: sprayer condition, type of nozzle and pattern of spray all vary from person to person.  Spraying without calibration means you may under apply material and not get the results you expect, or you may over apply and waste material and money.  Take a few minutes at least once a year to calibrate your sprayer using the steps below.

     1.  Using a tape measure or measuring wheel, mark off an area 20’ X 50’ (or 25’ X 40’).  Using these dimensions will give you an area of 1,000 sq. ft.  To define this area put some type of markers at the corners.  Soda pop or canned food cans work well.

     2.  Fill your sprayer with water only.  Whatever sprayer you have should be filled to a measured mark on the side of the sprayer.  This should be the one gallon mark on a one-gallon sprayer and two gallon mark on a two-gallon sprayer.  Any sprayer over two gallon capacity should just have two gallons in it.  Check your spray tip – make sure is not partially clogged or worn.  The best tip for flat surface application, such as a lawn, is a “flat fan,” even-spray tip, not a cone or “hollow circle” tip.

     3.  Take the sprayer that you filled with water and spray the 1,000 sq. ft. area.  Spray the entire area as you would normally.  If you have a one-gallon sprayer and you run out before you have covered the 1,000 sq. ft. area, you are applying too heavily.  Start over again and apply at a lighter and quicker rate.  The minimum amount of water to apply on a 1,000 sq. ft. is one gallon.

     4.  Once you have finished spraying, look at the sprayer volume measurement and see how much water you have left in your sprayer.  Subtract this amount from the original volume and this is how much water you used to cover 1,000 sq. ft.

     5.  For example, the amount of water you used to cover the 1,000 sq. ft. was 1 ½ gallon.  If the label calls for 4 oz. per 1,000 sq. ft., then put 4 oz. of material in 1 ½ gallon of water and spray the 1,000 sq. ft.  You may have used less or more but the goal is to determine how much water you apply to a 1,000 sq. ft.  Then it is so much material to that amount of water for 1,000 sq. ft.  You are now finished with the calibration.


 Most labels will say to use between 1 and 2 ½ gallons of water per 1,000 sq. ft.  That is the amount of water you should be applying when you spray.  

If you need assistance or have further questions please call us.  Remember that calibrating your sprayer is the ONLY WAY to know if you are applying the material correctly.

These steps are good for any single nozzle sprayer, whether hand held or back pack.  If you have a motorized pump on a large tank (15, 25 or 50 gallon) sprayer with a spray wand or a multiple nozzle (boom) sprayer we can help you calibrate that also!