PawExact

Setup boundary guide

How much litter should you put in Litter-Robot 4?

Use the raised MAX fill line as a boundary and record physical bed level before blaming litter, sensing, screening, or cycling.

Decision rail

Four checks, in order

Passing one check does not override a failure or unknown in the next. This is a compatibility decision, not a popularity ranking.

  1. 01Physical line

    Check the globe, not only the app

    Use the raised MAX line as the visible boundary and remove excess litter before interpreting another symptom.

  2. 02Weight

    Overfill adds load

    Extra litter weight can interfere with normal cycling, but weight alone does not diagnose every cycle interruption.

  3. 03Screen

    Observe clean-litter return

    Particle shape and material can still produce waste below MAX, so record the physical level with the screen outcome.

  4. 04Sensor

    Separate measured and displayed level

    Light or translucent litter may affect readings; a displayed low level is not proof the bed is physically low.

Published boundary

What Litter-Robot actually says

These statements describe classes and limits. They are not PawExact tests and do not automatically approve every product using the same marketing term.

OfficialLitter-Robot 4
“We recommend a high-quality, standard-weight, clay-based clumping litter”
Official source
OfficialLitter-Robot 4
“Some silica gel litter beads and crystals can also be used with Litter-Robot, as long as they pass through the screen. However, translucent or white-colored litter (most often seen in crystal litter) may impact the litter level and Drawer Full Indicator (DFI) accuracy in Litter-Robot 4 and are therefore not recommended.”
Official source
OfficialLitter-Robot 4
“Alternative, plant-based litters typically do not work with Litter-Robot as these may not be filtered properly through the sifting system.”
Official source

Exact-product records

Products that show why the class label is not enough

The products below illustrate different reasons the same physical fill boundary may not produce the same screening or sensor result.

Single report1 public report

Really Great Cat Litter

Tuft + Paw

Material
Tofu
Clumping
Clumping
Weight
Lightweight

One report ties long-particle screen loss to a relatively low fill condition; it is not an official percentage threshold.

Compatible with conditions

Read exact record
Community verified3 public reports

Original Health Monitoring Litter

PrettyLitter

Material
Silica Crystal
Clumping
Non Clumping
Weight
Lightweight

Light or translucent crystals can complicate level readings, so compare the app with the physical bed.

Compatible with conditions

Read exact record
Single report1 public report

Low Tracking & Dust Control

World's Best Cat Litter

Material
Corn
Clumping
Clumping
Weight
Lightweight

Large granules were reported entering the drawer; fill level belongs with any repeat observation.

Not recommended

Read exact record

Before a larger purchase

A small, observable first-use check

This is not a controlled test protocol. It is a way to notice an obvious mismatch before treating one successful cycle as proof.

  1. Check 1Level the bed and confirm it is at or just below the raised MAX line.
  2. Check 2Photograph the physical level and note the app reading before changing litter or calibration.
  3. Check 3Run several normal cycles and inspect the drawer for clean litter, clump fragments, or pooled moisture.
  4. Check 4If cycling remains abnormal after correcting overfill, follow manufacturer troubleshooting rather than assigning the cause to the litter alone.

Known limits

What the current evidence cannot prove

  • The official MAX boundary does not define one ideal volume for every material density or particle shape.
  • PawExact has not measured motor load, screen loss, or sensor accuracy at controlled fill depths.
  • A fill correction cannot by itself identify firmware, sensor, placement, obstruction, or mechanical faults.

Evidence readiness

What this guide can support today

This checkpoint separates a useful answer from claims the current official rules and exact records still cannot support. It is an editorial evidence review, not a PawExact test.

Question scope
The first question is whether the leveled physical bed is above the raised fill line, not whether the app says low or a bag supplies a particular weight. Only then interpret cycling, refill, or screen-loss symptoms separately.
Direct official boundary
The current no-cycle troubleshooting page says to remove excess litter above the fill line and also lists other possible causes, including drawer, sleep mode, sensor, placement, and mechanical conditions. The Hopper FAQ describes a default target at or just below MAX, not a universal measured mass.
Exact-product evidence
Current product reports can illustrate sticking, screening, or reading conditions, but they do not measure an ideal fill mass across formulas. No report overrides the physical MAX boundary.
Remaining gap
Correcting overfill does not establish that litter caused or cured a cycle interruption: the official troubleshooting list has independent branches. PawExact has no density-to-depth table, controlled motor-load data, or formula-specific ideal weight.

Intent boundary

Keep the next question narrower

Use this page for the physical fill boundary, not a universal bag-weight calculation. The current troubleshooting source says remove excess above the line; it does not establish a product-specific optimum below it.