Toilet Flush Performance Chart: MaP Scores All Brands

Choosing a toilet based on appearance or price tag alone leaves out the single most important performance variable: how many grams of solid waste the toilet can move in one flush. That number, published by the MaP testing program, is the only standardized, third-party metric that compares every brand on the same scale. It removes marketing language from the equation entirely.

This flush performance chart consolidates published MaP scores, gallons-per-flush (GPF) ratings, EPA WaterSense certification status, and trapway dimensions for the most widely purchased toilet models sold in North America. Whether you are renovating a bathroom, replacing a chronic clogger, or specifying fixtures for a commercial property, this reference gives you the comparative data you need in one place. For a curated shortlist of top performers, see our guide to the best flushing toilets.

What Is MaP Testing and Why Does the Score Matter?

The MaP protocol was created to fill a critical gap left by earlier efficiency standards like the federal 1.6 GPF mandate introduced in 1994. That mandate reduced water consumption but said nothing about whether a toilet could actually clear waste in one flush. Water utilities realized customers were doubling and tripling flushes to compensate for weak performance, erasing any water savings. MaP testing began in 2003 and is now cited by engineers, building managers, and plumbing contractors as the primary benchmark for flush effectiveness.

Each toilet is tested at least three times using a soybean paste surrogate formulated to replicate the density and cohesion of human solid waste. The paste is shaped into specific gram quantities and placed in the bowl. Testers increase the payload size until the toilet fails to clear completely. The highest payload cleared consistently becomes the model's MaP score. All results are publicly available at map-testing.com, updated annually.

Two additional numbers always accompany a MaP score for full context: GPF (gallons per flush) and EPA WaterSense status. A 1,000-gram score at 1.6 GPF is impressive. The same score at 1.28 GPF is exceptional, because it proves the toilet moves maximum waste with 20 percent less water. EPA WaterSense certification requires 1.28 GPF or below with a minimum 350-gram MaP score, which virtually every certified toilet far exceeds.

Which Toilet Brands Score Highest in MaP Testing?

The table below consolidates MaP data for widely purchased toilet models. MaP scores reflect the most recent published test results from map-testing.com. Where a model has been tested at multiple GPF settings, the primary residential GPF is shown. WaterSense column reflects EPA certification status at time of research.

The winner row -- TOTO Drake II -- represents the convergence of maximum flush performance and water efficiency at 1.28 GPF with a 1,000-gram MaP score and EPA WaterSense certification. It is among the most specified toilets by plumbing contractors and appears repeatedly at the top of best flushing toilets rankings for these reasons.

How Do MaP Scores Compare Between TOTO, Kohler, and American Standard?

The key differentiator between brands at the top MaP tier is how they reach the 1,000-gram result. TOTO's Double Cyclone system uses two nozzles at the base of the bowl instead of a traditional rim channel, directing water in a spiral pattern that covers more bowl surface area while using 1.28 GPF. This produces both a powerful flush and a cleaner bowl with less rim scaling over time. The TOTO Drake II and UltraMax II both use this system.

American Standard's Champion 4 achieves the same 1,000-gram result with a fundamentally different approach: a 4-inch flush valve that releases the tank volume in a single wide surge rather than a narrow stream. The valve aperture is roughly four times larger than a standard 2-inch flapper, which creates higher hydraulic velocity and a wider bowl wash. The trade-off is that the Champion 4 uses 1.6 GPF in its standard form, though the Champion 4 Max achieves the same score at 1.28 GPF. Read the full American Standard Champion 4 review for a deeper engineering breakdown.

Kohler's Class Five flushing system uses a canister-style flush valve that opens to 90 percent of the flush valve's total area, providing fast water release similar in concept to the Champion 4 but packaged in a quieter, lower-profile tank design. Kohler's Cimarron consistently scores 1,000 grams at 1.28 GPF and is frequently chosen for households where flush noise is a concern, since the canister mechanism is quieter than either the Champion valve or the Double Cyclone nozzles.

Gerber does not receive the same consumer awareness as the three major brands, but the Viper and Maxwell lines are regularly specified by professional plumbers precisely because they score 1,000 grams in MaP testing and are straightforward to service. Gerber parts availability is strong across plumbing supply houses. For a detailed comparison, see our American Standard vs Gerber head-to-head.

What MaP Score Should You Look for When Buying a Toilet?

The 350-gram floor set by EPA WaterSense represents the absolute minimum a toilet must clear to earn certification. In practice, that threshold was set deliberately low to allow a broad range of fixtures to qualify, and many fixtures scoring near 350 grams will require double flushing under real household conditions. Most plumbing professionals recommend ignoring any model that scores below 500 grams.

The practical MaP tiers work as follows: scores between 350 and 499 grams are marginal and should only be considered in low-use settings such as a guest bathroom used a few times per week. Scores between 500 and 699 grams represent baseline acceptable residential performance. Scores between 700 and 899 grams are solid -- these toilets will handle typical household use without chronic clogging issues. Scores between 900 and 1,000 grams represent top-tier performance, appropriate for any setting including large families, commercial restrooms, or households with individuals who have health conditions affecting waste volume.

One important nuance: MaP score is measured as a single-flush result at standard water pressure (typically 45 to 80 PSI). Homes with chronically low water pressure, typically below 25 PSI, may experience real-world performance below the published MaP score because the test protocol assumes adequate supply pressure. If low water pressure is a known issue in your home, prioritize pressure-assist flush technology. Gerber's Viper, which uses a pressure-assist mechanism, maintains its 1,000-gram performance even at pressures above 20 PSI. Learn more in our pressure-assist vs gravity flush comparison.

Does a Larger Trapway Guarantee a Higher MaP Score?

The trapway is the passage through which waste travels from the bowl to the drain. A wider trapway reduces the chance that a large or irregular waste mass will become stuck in transit, which is why American Standard markets the Champion 4's 2-3/8-inch fully glazed trapway as a clog prevention feature. In independent owner reviews, the Champion 4 does receive consistently high marks for clog resistance specifically, even when compared to other models with 1,000-gram MaP scores.

However, the TOTO Drake II with its 2-1/8-inch trapway earns equally high owner ratings for clog resistance because its Double Cyclone flush generates sufficient hydraulic force and flow coverage to move waste through the narrower opening without incident under normal household conditions. The engineering difference becomes relevant primarily in high-volume or commercial applications where larger waste masses are more frequent.

Budget one-piece designs from Woodbridge and Swiss Madison use 2-inch trapways paired with 1.28 GPF gravity systems, which is the tightest practical combination. These models score 800 grams in MaP testing, which is strong performance, but their smaller trapway creates a marginally higher probability of obstruction under extreme load compared to 1,000-gram models with wider openings. For most buyers, an 800-gram score with a 2-inch trapway represents excellent value. See our one-piece vs two-piece toilet guide for design context.

The trapway surface coating also matters. A fully glazed trapway -- meaning the ceramic glaze extends through the full length of the trapway passage rather than stopping at the bowl exit -- significantly reduces waste adhesion and the friction that slows waste transit. American Standard specifies a fully glazed trapway on the Champion 4 and Cadet 3. TOTO applies its CeFiONtect ion-barrier glaze through the trapway as well. Unglazed or partially glazed trapways, more common in entry-level models, create more friction and are associated with higher clog frequency even when the diameter is adequate.

MaP Score by Flush Technology: Gravity vs Dual Flush vs Pressure-Assist

Flush technology is a system-level variable that shapes what MaP performance is achievable at a given GPF rating. The three main categories found in residential toilets are gravity-fed single flush, dual flush, and pressure-assist.

Gravity-fed single flush is the most common residential technology. Water falls by gravity from the tank through the flush valve into the bowl, and the siphon action of the trapway draws waste out. At 1.6 GPF, gravity systems have always been capable of 1,000-gram performance -- the original pre-1994 toilets that used 3.5 to 5.0 GPF were gravity-fed and rarely clogged because the sheer water volume overwhelmed any passage. The engineering challenge since 1994 has been achieving 1,000-gram performance at 1.28 GPF with gravity, which brands like TOTO, American Standard, Kohler, and Gerber have solved through flush valve geometry and bowl design optimization.

Dual flush systems introduce a compromise: a smaller flush volume (typically 0.8 or 1.0 GPF) for liquid waste and a full flush volume (1.0 to 1.28 GPF) for solid waste. The MaP score for a dual flush toilet is assessed at the full flush setting. The TOTO Aquia IV scores a perfect 1,000 grams at its 1.0 GPF full flush setting, matching the ceiling that TOTO's single-flush models achieve at 1.28 GPF, so it is one of the rare dual flush designs that gives up no MaP performance for its water savings. The water savings from dual flush are real -- average household water consumption studies show dual-flush users reduce toilet water use by roughly 20 to 30 percent compared to single-flush 1.28 GPF users -- and many other dual flush designs do post modestly lower MaP scores than the best single-flush models at equivalent GPF. For more on this tradeoff, see our are dual flush toilets worth it analysis.

Pressure-assist systems use compressed air stored in a sealed inner tank to boost water delivery velocity. Pressure-assist toilets flush with more force than gravity designs at equivalent GPF, which is why they are common in commercial settings and in homes with chronic clogging history. Gerber's Viper uses pressure-assist technology and achieves 1,000 grams. The trade-offs are higher flush noise, higher purchase price, more complex repair requirements, and sensitivity to inlet water pressure (the compressed air charge requires adequate supply pressure to build properly). Pressure-assist toilets are not recommended for homes with supply pressure below 20 PSI.

Budget Brand MaP Performance: Woodbridge, Swiss Madison, and DeerValley

The Woodbridge T-0001 one-piece elongated toilet has become one of the most widely purchased value-tier options in North America, driven by its one-piece design, soft-close seat, dual flush operation, and 800-gram MaP score. At its price tier, few competitors match this combination. The ceramic quality and glaze consistency have improved across production runs from 2022 onward, addressing earlier complaints about micro-surface roughness that complicated cleaning.

Swiss Madison offers the St. Tropez and Sublime II lines targeting buyers who prioritize European-influenced minimalist design. Both score 800 grams in MaP testing. The 2-inch trapway in these models is the primary performance limitation -- adequate for standard household use but narrower than the best American Standard and TOTO designs. Swiss Madison's dual flush systems use push-button actuators embedded in the tank lid, which some owners find less intuitive than traditional handle systems. Replacement actuator parts require sourcing through Swiss Madison's direct parts program rather than standard plumbing supply houses.

DeerValley has entered the North American market with elongated one-piece designs that achieve 800-gram MaP scores and WaterSense certification at competitive price points. Long-term owner feedback on DeerValley products is more limited than on TOTO, American Standard, or Kohler due to the brand's shorter North American market history, but first-year reviews are consistently positive for flush performance and bowl cleanliness.

MaP Score vs GPF: Understanding the Efficiency-Performance Matrix

The relationship between MaP score and GPF is the core analytical question for any toilet purchase. The ideal combination is maximum MaP score at minimum GPF, and the market leaders in 2026 deliver exactly that: 1,000 grams at 1.28 GPF. This was not achievable in 2003 when MaP testing began. A decade of engineering investment by TOTO, American Standard, Kohler, and Gerber has made 1,000 grams at 1.28 GPF the new baseline expectation for any premium toilet.

The efficiency-performance matrix below illustrates where major models fall when both variables are considered simultaneously. The upper-right quadrant (high MaP + low GPF) is the target zone.

For most buyers, the practical recommendation simplifies to: find a model in the best quadrant (1,000 grams, 1.28 GPF, WaterSense certified) that fits your bowl shape preference, rough-in dimension, and budget. There are more than twenty such models available from four major brands, spanning a wide price range from entry-tier (Cadet 3) to premium (TOTO UltraMax II one-piece).

How to Use This Chart When Shopping for a Toilet

Start with your rough-in dimension. Standard North American homes use a 12-inch rough-in (the distance from the wall behind the toilet to the center of the drain). Some older homes use 10-inch or 14-inch rough-ins, and choosing the wrong rough-in dimension means the toilet will not fit regardless of its MaP score. Most MaP-tested models are available in 12-inch rough-in as the standard; 10-inch and 14-inch versions are typically specified as separate SKUs. Verify your rough-in before ordering.

Next, decide on bowl shape: elongated or round front. Elongated bowls are approximately 2 inches longer front-to-back and are more comfortable for most adults, though round-front bowls are sometimes necessary in smaller bathrooms. Both shapes are available across the full MaP performance range. The MaP score is not affected by bowl shape -- flush valve and trapway geometry drive the score, not the bowl outline.

Determine your GPF preference and whether EPA WaterSense certification matters for your region. If you are in a state with water efficiency mandates (California, Colorado, Texas drought zones, portions of the Pacific Northwest), WaterSense certification is not optional. If you are in a state without mandates, you can choose between 1.28 GPF WaterSense models and 1.6 GPF standard models. Given that 1,000-gram MaP performance is achievable at 1.28 GPF, there is no performance advantage to choosing 1.6 GPF in current-generation toilets.

Finally, consider comfort height versus standard height. ADA-compliant comfort height bowls sit 16.5 to 18 inches from floor to rim, comparable to a standard chair. Standard height bowls sit at 14 to 15 inches. Comfort height is easier for adults with mobility limitations and for taller adults generally. Children under eight years old may find comfort height less ergonomic. Both heights are available in 1,000-gram MaP models across all major brands. For ADA-specific guidance, see our ADA compliant toilet guide.

• Best Flushing Toilets: Top Picks for Every Budget
• American Standard Champion 4 Review
• Pressure-Assist vs Gravity Flush Toilets
• One-Piece vs Two-Piece Toilets: Which Is Better?
• ADA Compliant Toilet Guide: Height, Access, and Top Models