Getting the right fit for a garbage disposal splash guard is less about “guessing” and more about precise measurement. If the guard is even an $1/8-inch off, you’ll deal with annoying leaks, excessive noise, or slow drainage.
This guide focuses specifically on how to measure your splash guard size, how to identify your mounting system, and how to ensure your replacement part fits perfectly the first time.
Quick Reference: Most Common Sizes
If you don’t have a ruler handy, you can often determine the size based on the mounting style and brand.
| Mounting System | Common Brand Examples | Standard Splash Guard Size | Measurement Location |
| 3-Bolt Mount | InSinkErator, Moen, GE, Kohler | 3-3/8 inches | Internal diameter of the metal sink flange. |
| EZ Mount | Waste King, Whirlaway, Montgomery Ward | 3-1/4 inches | The outer diameter of the removable rubber rim. |
| Universal / Large | Specialty High-HP Models | 3-1/2 inches | Total width of the drain opening. |
How to Measure Your Splash Guard: Step-by-Step
To get an accurate measurement, you should measure both the old splash guard (if it isn’t too deformed) and the sink flange opening.
1. Measure the Splash Guard Diameter
If your splash guard is still in one piece, remove it from the drain.
- The Outer Diameter (OD): Lay the guard flat on a counter. Measure from the outer edge of one side to the outer edge of the other, passing through the center.
- The Inner Ring: Some guards have a secondary “lip” that sits inside the disposal. Measure this if you are buying a “drop-in” style guard for an InSinkErator.
2. Measure the Sink Flange (The Most Accurate Method)
If your old guard is missing or melted/warped, measuring the sink flange is the most reliable way to find the correct size.
- Step A: Clear any debris from the sink drain.
- Step B: Using a tape measure or caliper, measure the inner diameter of the metal ring (the flange) that sits in your sink.
- Step C: Most standard flanges will measure exactly 3-3/8 inches or 3-1/4 inches.
Pro Tip: If your measurement falls exactly between these two (like 3-5/16″), look at the underside of the disposal. If it’s held up by three metal bolts, round up to 3-3/8″. If it’s a plastic twist-lock, it’s likely 3-1/4″.
Identifying the Mounting System
The size of the splash guard is almost always dictated by the “mount”—the hardware that connects the disposal to the sink.
The 3-Bolt Mount (Industry Standard)
This is the most common system. Look under your sink; if you see a metal ring with three heavy-duty bolts tightening the unit against the sink, you have a 3-bolt mount.
- Required Size: Usually 3-3/8 inches.
- Style: These guards are often “drop-in” (Evolution series) or “compressed” (Badger series) between the flange and the unit.
The EZ Mount (Proprietary Style)
This system is common on Waste King units. It uses a plastic mounting assembly that twists into place.
- Required Size: Usually 3-1/4 inches.
- Style: These guards are typically very flexible and have a distinct flared “lip” that hangs onto the edge of the flange.
Troubleshooting “In-Between” Sizes
Sometimes, a manual measurement can be confusing due to the thickness of the rubber or the age of the unit. Use this table to troubleshoot your findings.
| If your measurement is… | Your Mounting System is likely… | You should buy… |
| ~3.25 inches | EZ Mount (Plastic) | 3-1/4″ Waste King Style |
| ~3.375 inches | 3-Bolt (Metal) | 3-3/8″ Standard/InSinkErator Style |
| ~3.50 inches | Commercial or European | 3-1/2″ Universal Large |
Why Precise Measurement Matters
Using a splash guard that is the wrong size, even by a tiny margin, causes three main issues:
- Drainage Resistance: If the guard is too large, the rubber flaps will be under too much tension. They won’t open easily under the weight of water, leading to a “sink full of water” even when the disposal is off.
- Increased Vibration Noise: The splash guard acts as a gasket. If it doesn’t fit snugly, the metal-on-metal vibration of the disposal will resonate through the sink, making the machine sound much louder.
- Safety Hazards: A loose splash guard can be “sucked” into the grinding chamber or allow food particles to shoot out of the drain at high speeds (the “splash back” effect).
