MaP Flush Score Explained: What It Means for You

A toilet manufacturer can print almost anything on a box. "Powerful flush." "Clog-free." "Maximum performance." What those phrases actually mean in practice has historically been impossible to verify without a plumbing background and access to a flow lab. The MaP (Maximum Performance) program was created specifically to cut through that marketing language by putting every toilet through an identical, repeatable flushing test and publishing the results so consumers and plumbers can compare models on a level field.

Understanding what MaP scores mean, how they are measured, what thresholds matter, and how they interact with water use (gallons per flush, or GPF) is the difference between buying a toilet that works reliably for ten years and buying one that you plunge three times a week. This guide walks through all of it, covering the methodology behind the testing, the score ranges and what they predict, how top-rated models from TOTO, Kohler, American Standard, Woodbridge, Swiss Madison and Gerber compare, and how MaP data fits into a complete buying decision. For a broader side-by-side look at the top-performing toilets overall, see our roundup of the best flushing toilets.

What Is MaP Flush Testing and How Does It Work?

The test media used in MaP testing -- a dense soybean paste of standardized consistency -- was chosen because it closely approximates the density and cohesion of human fecal matter without the biological and safety complications of using the real thing. The paste is shaped into standardized balls of known weight and loaded into the bowl. The flush is triggered once, and engineers observe and measure what is cleared. The test is repeated multiple times per model to account for variation, and the final score represents the maximum the toilet can reliably clear.

It is worth noting that MaP tests bowl clearance, not drain-line performance. A toilet can score 1000 grams and still experience issues downstream if a home has old, undersized or partially blocked drain lines. However, for the bowl-level performance that most clogging problems originate from, MaP scores are the most reliable objective indicator available to consumers.

What Is a Good MaP Score for a Toilet?

How Does MaP Score Relate to Gallons Per Flush (GPF)?

The federal maximum for new residential toilet installations in the United States is 1.6 gallons per flush, established by federal law in 1992. EPA WaterSense certification, which requires 1.28 GPF or lower, sits 20 percent below that threshold. High-efficiency toilets (HETs) typically use 1.28 GPF, while ultra-high-efficiency models can go as low as 0.8 GPF or use a dual-flush system with a 0.8-gallon partial flush and a 1.28-gallon full flush.

Here is the practical consequence for buyers: a toilet from the late 1990s using 3.5 gallons per flush used sheer water volume to move waste. Modern low-flow toilets achieve comparable or better performance by optimizing the shape of the rim wash, the angle of the trapway, the size of the flush valve, and the geometry of the bowl. A TOTO Drake using 1.28 GPF scores 1000 grams on MaP. An older or poorly designed 1.6-gallon toilet might score 500 grams. More water does not guarantee better flushing. The engineering does. To understand more about how water efficiency and flush power intersect, see our guide on everything you need to know when buying a toilet.

Which Toilet Has the Strongest Flush?

What Is the Best Toilet for Preventing Clogs?

Top-Rated Toilets Ranked by MaP Score

The comparison below covers widely available models from major brands. MaP scores are sourced from published manufacturer data and third-party testing records. Scores can vary slightly between SKUs and flush volumes within the same product family, so always confirm the score for the exact model number before purchasing.

A few patterns emerge from that table. Every model from TOTO in the 1.28-gallon class performs at or above 800 grams, which reflects TOTO's engineering investment in flush dynamics. American Standard's Champion 4 hits 1000 grams but at the higher 1.6-gallon rate, meaning you sacrifice some water savings for that ceiling score. Gerber produces less marketing noise than TOTO or Kohler but consistently earns strong MaP scores relative to price, which is why plumbers frequently recommend Gerber models in budget-conscious renovations. To dig deeper into how to evaluate all of these factors together, read our complete guide on how to choose a toilet.

How to Look Up a MaP Score Before You Buy

The MaP database is publicly available at map-testing.com. You can search by manufacturer name, model series, or product catalog number. The database is updated periodically as new models submit for testing, and it shows the MaP score alongside the flush volume tested, so you can confirm you are looking at the 1.28-gallon version of a model rather than the 1.6-gallon variant, which may have a different score.

When searching, use the official model number rather than the marketing name. TOTO lists the Drake under catalog numbers like CST744E (elongated, 1.28 GPF) or CST743E (1.6 GPF version). Kohler lists the Cimarron under K-3609 or K-3887 depending on configuration. American Standard's Champion 4 is catalog number 2034.014 for the round model and 2021.014 for the elongated version. If you cannot find the exact model in the MaP database, that is worth noting before you commit to the purchase.

Some retailers, particularly big-box stores, carry proprietary model numbers that are exclusive to their stores but are manufactured by the same brands under a different SKU. In those cases, searching the MaP database by brand and approximate specifications can sometimes surface the base model. If no data is available, the safest course is to buy a model with a confirmed MaP score rather than relying on retailer claims.

MaP Score vs. Manufacturer Flush Claims: What to Trust

Every major toilet brand uses proprietary flush-system marketing names. TOTO calls its technology G-Max, Double Cyclone, or Tornado Flush depending on the series. Kohler uses AquaPiston and Revolution 360. American Standard uses Champion, ActiClean, and Right Height. Gerber uses CleanCurve and HET. These names describe real engineering differences in how the flush mechanism works, but they are not standardized across brands and do not translate into a score you can compare.

A "Champion" flush and a "G-Max" flush are both proprietary names. A 1000-gram MaP score and an 800-gram MaP score are universal numbers. The proprietary name tells you the engineering approach. The MaP score tells you what that approach actually achieved when tested under objective conditions. Both pieces of information are useful, but when they conflict -- when a toilet has a bold marketing name but a weak or unlisted MaP score -- the MaP data is the one to trust.

It is also worth noting what MaP does not cover. The program tests bulk waste clearance. It does not formally test paper clearance, bowl rim-wash coverage, or how cleanly the bowl is rinsed after flushing. For a toilet with a rimless design, the key advantage is rim hygiene, not necessarily MaP score improvement. The TOTO UltraMax II uses Tornado Flush to deliver a full rim rinse without a rim channel, which reduces bacteria buildup. That is a valuable feature that the MaP number alone does not capture, which is why reading the full specification sheet alongside the MaP score gives a more complete picture.

Top Toilet Picks by MaP Performance Tier

Buying Guide: Using MaP Scores in a Complete Decision

MaP score is a key data point, but buying a toilet involves several interconnected factors. Here is how to use MaP alongside the other specifications that actually predict whether a toilet will perform well in your specific bathroom.

Step 1: Establish your MaP floor

Before comparing models, decide on a minimum MaP score for your situation. A guest bathroom used only occasionally by adults can function adequately with a 600-gram score. A master bathroom used by a family of four every morning needs 800 grams at a minimum. Any household with a documented history of clogs, or with occupants whose waste volume is high, should target 1000 grams and consider nothing below 800 grams as a fallback.

Step 2: Match GPF to your water situation

If your municipality offers rebates for WaterSense-certified toilets, or if you have a septic system with specific volume limits, 1.28 GPF (WaterSense certified) is the bracket to buy within. If your drain line is old or your home has a long horizontal pipe run that requires water volume to carry waste, a 1.6 GPF model may be the practical choice even at the cost of losing WaterSense certification.

Step 3: Confirm the rough-in measurement

Before any other decision, measure the rough-in: the distance from the finished wall behind the toilet to the center of the floor drain. Standard rough-in is 12 inches, but 10-inch and 14-inch rough-in toilets exist. Buying a toilet for a 12-inch rough-in when your bathroom has a 10-inch drain means the toilet will not fit against the wall. Our detailed guide on toilet buying covers this measurement process step by step.

Step 4: Choose bowl shape for the space

Elongated bowls add roughly 2 inches of front-to-back depth compared to round bowls. In a bathroom with 30 inches or more of clear space in front of the toilet, elongated is the more comfortable choice for adults. In compact bathrooms, round bowls preserve clearance. Comfort height (16 to 18 inches rim height) is easier on knees and hips for most adults and is now the default in many product lines. Standard height (15 inches) is better for shorter occupants and children. See our full breakdown in the guide on round versus elongated toilets for sizing context.

Step 5: Factor in trapway design

A fully glazed trapway reduces friction as waste moves through, contributing to clog resistance beyond what the MaP score alone captures. Trapway width matters too: 2 inches is the minimum standard, 2-1/8 inches (TOTO Drake) is better, and the American Standard Champion 4's 2-3/8-inch trapway is the widest available in the standard residential class. Skirted toilets conceal the trapway for easier exterior cleaning but use the same internal trapway engineering as exposed designs.

Which Toilet Offers the Best Value for the MaP Score?

Common questions

Frequently Asked Questions

? What does MaP stand for in toilets?

MaP stands for Maximum Performance. It is the name of the independent third-party testing program that measures how many grams of solid waste a toilet can clear in a single flush. The program was developed with input from North American water utilities and publishes results publicly at map-testing.com.

? Is a higher MaP score always better?

A higher MaP score means the toilet is capable of clearing more waste in a single flush, which reduces clogging and eliminates the need for double-flushing. For most households, higher is better. However, a 1000-gram toilet is not necessarily the only viable choice. A family of two adults with no clogging history may find an 800-gram toilet performs perfectly for their needs.

? What is the maximum MaP score a toilet can receive?

The maximum MaP score awarded by the testing program is 1000 grams. Several widely available residential toilets achieve this ceiling score, including the TOTO Drake, the American Standard Champion 4, and some configurations of the Kohler Cimarron.

? Does a toilet need a high MaP score to be WaterSense certified?

No. EPA WaterSense certification requires that a toilet use 1.28 gallons per flush or less and pass a minimum flush performance standard, but WaterSense does not specifically require a MaP score. A toilet can carry WaterSense certification with a relatively modest MaP score. MaP and WaterSense are separate programs that complement each other.

? How is the MaP test conducted?

MaP tests use a standardized soybean-paste media formulated to approximate the density and consistency of human waste. The media is shaped into measured balls of known weight, placed in the toilet bowl, and flushed once. Engineers measure what is cleared. The test is repeated multiple times per model, and the final score represents the maximum grams the toilet can reliably clear in a single flush under identical test conditions.

? Can I look up a specific toilet's MaP score before buying?

Yes. The MaP database is publicly available at map-testing.com. You can search by manufacturer name, product series, or model number. The database shows the MaP score alongside the specific flush volume tested, so you can confirm you are looking at the correct configuration of the model you plan to purchase.

? Does MaP testing cover paper clearance as well as solid waste?

The primary MaP protocol tests solid waste clearance using the soybean-paste media. The program has expanded to include optional paper-clearance testing in some of its protocols, but the widely cited MaP score refers specifically to the grams-of-media cleared in the standard solid-waste test. A high MaP score is a strong indicator of overall flush power, but it specifically measures solid waste performance.

? Which MaP score should I aim for in a family bathroom?

For a bathroom used by a family of three or more people, target a MaP score of 800 grams or higher. A score of 1000 grams provides the most clog-resistant performance possible from a gravity toilet and is the recommendation for heavy-use bathrooms or any household with a history of clogging.

? Does using more water per flush mean a higher MaP score?

Not necessarily. Water volume and MaP score are related but not directly proportional. The TOTO Drake earns 1000 grams at 1.28 GPF, while some 1.6 GPF toilets score well below 800 grams. Bowl geometry, flush valve size, trapway width, and water velocity all influence MaP score more than raw volume alone. Engineering efficiency matters more than gallons.

? What is the difference between MaP and flush rating from the manufacturer?

Manufacturer flush ratings are proprietary and not comparable across brands. A Kohler "AquaPiston" score and a TOTO "G-Max" rating use different methodologies and different media, so they cannot be directly compared. MaP scores are produced by an independent third party using an identical protocol on every model, which makes them comparable across all brands tested.

? Are pressure-assist toilets tested by MaP?

Yes. Pressure-assist toilets can be submitted for MaP testing and many are. Pressure-assist toilets tend to earn high MaP scores because their compressed-air assisted flush delivers a fast, forceful discharge. However, the MaP testing protocol is the same regardless of flush mechanism, so a pressure-assist 1000-gram score is directly comparable to a gravity 1000-gram score in terms of waste clearance.

? Does the Gerber Viper have an official MaP score?

The Gerber Viper has been listed in the MaP database with scores at or around 800 grams for the standard 1.28 GPF configuration. As with any model, checking map-testing.com for the specific model number you intend to buy is the best way to confirm the current published score, since scores can vary between production runs and SKU variants.

? Is the TOTO Drake really the best toilet for MaP performance?

The TOTO Drake's combination of a 1000-gram MaP score at 1.28 GPF with EPA WaterSense certification is the best documented pairing of flush power and water efficiency in the gravity residential category. The American Standard Champion 4 also scores 1000 grams, but at 1.6 GPF. For buyers who want the ceiling score at the lowest water use, the Drake is the benchmark. For buyers who want the ceiling score regardless of water use, both are equivalent on MaP performance.

? Does bowl shape (round vs elongated) affect MaP score?

Bowl shape can influence MaP results within the same toilet family. Elongated bowls have a longer front projection, which can affect how the flush siphon forms relative to waste position. Manufacturers often publish separate MaP scores for round and elongated versions of the same model. Always look up the MaP score for the specific bowl shape you plan to buy, not just the product family average.

? What is the minimum MaP score that still works for residential use?

The MaP program considers 350 grams the minimum passing score for residential adequacy, but in practice most plumbing professionals recommend a minimum of 500 grams for a toilet that will be used regularly. Below 500 grams, clogs and double-flushing are likely to occur frequently in typical household use, particularly for a bathroom used by multiple adults.

? Does the Swiss Madison St. Tropez have a MaP score?

The Swiss Madison St. Tropez and its related models have been submitted for MaP testing. Results depend on the configuration (wall-hung or floor-mounted, and which tank or in-wall carrier is paired with the bowl). Wall-hung toilet MaP scores can vary more than floor-mount models because the flush pressure is partly determined by the in-wall flush valve system rather than the bowl alone. Check map-testing.com for the current listing of the specific St. Tropez SKU you are considering.

? Does a higher MaP score mean fewer double flushes?

Yes, directly. Double flushing happens when the first flush does not fully clear the bowl, requiring a second flush to remove remaining waste. A toilet with a 1000-gram MaP score is capable of clearing waste in amounts that exceed typical household deposits on a single flush, which is why owner reviews of high-MaP toilets consistently note the absence of double flushing as a frequently cited benefit.

? How does a dual-flush toilet's MaP score work?

Dual-flush toilets have two flush volumes, typically 0.8 GPF for liquids and 1.28 GPF for solids. MaP testing for dual-flush toilets is conducted on the full-flush setting (1.28 GPF), because that is the flush used for solid waste clearance. The partial flush (0.8 GPF) is not MaP-scored for solid waste since it is intended for liquid waste only. When evaluating a dual-flush toilet for MaP purposes, confirm the score is from the full-flush cycle.

? Do all toilet brands submit for MaP testing?

No. MaP testing is voluntary. Major brands including TOTO, Kohler, American Standard and Gerber routinely submit their primary residential models. Some smaller or import brands do not participate, which means no publicly verifiable third-party performance score exists for those models. When a toilet you are considering has no MaP listing, that should be a factor in your decision.

? Can I trust a toilet's MaP score even if the manufacturer paid for the test?

Yes. Although manufacturers pay a submission fee to enter the MaP program, the testing is conducted by independent certified labs using a standardized protocol. The program was developed with water utility input specifically to be impartial, and the results are published publicly whether the score is strong or weak. The protocol does not allow manufacturers to cherry-pick results or influence grading, and the same test is applied to a budget toilet and a premium toilet without modification.

Sources

• EPA WaterSense, epa.gov/watersense
• MaP (Maximum Performance) flush testing, map-testing.com
• Manufacturer published specifications (TOTO, Kohler, American Standard)