Garden hoses are not a strict requirement for watering your garden, but they save considerable time and effort over hauling the watering can to various plants. Garden hoses have inside diameters of 1/2 inch, 5/8 inch or 3/4 inch. The male and female ends of the hose are often slightly larger than its inside diameter, so measuring isn't as simple as holding up a ruler at one end of the hose. Measure the hose diameter if you need to replace a damaged hose or connect it to an existing hose.
Disconnect all fittings or attachments from the ends of the garden hose, including couplings, soaker hoses, spray nozzles and lawn sprinklers.
Insert a 1/2-inch wooden dowel into one end of the hose and check the fit. Try a 5/8-inch wooden dowel and a 3/4-inch dowel until you find the size that has the best fit. There's no need to purchase dowels specifically to measure a garden hose. If you don't have dowels on hand, use other objects such as high-speed metal drill bits. Do not use wood paddle bits; they have pointed tips that could puncture the hose.
Remove the dowel from the inside of the garden hose. Hold a ruler against one end of the dowel and measure across the center of the dowel to find the true dowel diameter. This is simply a safeguard to ensure the actual measurement of the dowel is consistent with its label.