Plumbing Reference
DFU Chart by Fixture
Use this Drainage Fixture Unit chart to compare common plumbing fixture values under UPC and IPC assumptions. DFUs help estimate the wastewater load from toilets, sinks, showers, tubs, dishwashers, clothes washers, floor drains, and other fixtures before checking pipe sizing tables.
What Is a DFU in Plumbing?
DFU means drainage fixture unit. In plumbing, DFUs estimate the drainage load from each fixture so toilets, lavatory sinks, showers, tubs, washers, and other fixtures can be compared using a common fixture-unit value.
A DFU chart lists those fixture-unit values so you can add up the total load on a branch drain, building drain, or building sewer. The DFU total is only a planning step; final pipe sizing also depends on slope, venting, pipe orientation, developed length, and local code requirements.
Quick answer
A DFU chart gives each fixture a drainage load value so you can add up the total fixture load on a drain, branch, building drain, or sewer. The fixture-unit total is only the first step. Final pipe sizing still depends on the adopted code, pipe slope, horizontal versus vertical orientation, developed length, venting, fixture grouping, and local amendments.
To turn fixture values into a total, use the DFU calculator. To understand which part of the drainage system you are checking, review building drain vs building sewer.
Jump to common DFU values
Common DFU Chart: UPC vs IPC
The table below lists common planning values used by the BuildCalc DFU calculator. These values are intended for early estimating and code comparison. Always verify the final value against the adopted plumbing code, local amendments, and actual fixture type. For jurisdiction context, compare UPC vs IPC plumbing code differences or start with the state plumbing code lookup.
| Fixture | UPC DFU | IPC DFU | Notes |
|---|---|---|---|
| Toilet, private use | 3 | 4 | Common residential water closet value. Public-use or flushometer fixtures may differ. |
| Toilet, public use | 6 | 4 | Public-use toilet assumptions can vary by code, fixture type, and flush method. |
| Lavatory sink | 1 | 1 | Common bathroom sink fixture-unit value. |
| Shower | 2 | 2 | Typical value for a standard shower. Larger or multi-head showers may need review. |
| Tub / tub-shower | 2 | 2 | Common value for a bathtub or combination tub-shower. |
| Kitchen sink | 2 | 2 | Kitchen fixture groups may also include dishwasher, disposal, or island vent considerations. |
| Dishwasher | 2 | 2 | May discharge through a kitchen sink, air gap, disposal, or indirect connection depending on layout. |
| Garbage disposal | 1 | 1 | Often considered with the kitchen sink group. Check local code and fixture arrangement. |
| Clothes washer | 3 | 2 | Laundry values can differ between UPC and IPC assumptions. Standpipe and trap sizing also matter. |
| Laundry sink | 2 | 2 | Common value for a laundry tray or utility laundry sink. |
| Utility sink | 2 | 2 | May be used in garages, shops, laundry rooms, or utility spaces. |
| Mop sink / service sink | 3 | 3 | Common in janitor rooms, commercial spaces, garages, and service areas. |
| Floor drain | 2 | 2 | Actual requirements can depend on trap primer, location, indirect waste, and use. |
| Bar sink | 1 | 1 | Common value for a small prep sink, wet bar sink, or secondary sink. |
| Urinal | 2 | 4 | Urinal values can vary by code and fixture type. Public-use projects need careful review. |
| Bidet | 1 | 1 | Common residential bidet fixture-unit value. |
| Drinking fountain | 0.5 | 0.5 | Low fixture-unit value, but commercial accessibility and water supply rules may also apply. |
| Ice maker | 1 | 1 | Often involves indirect waste or small water connection details depending on installation. |
On mobile, scroll the table sideways to compare all columns.
Fixture-Specific DFU Values
The fixture-unit chart above gives a quick comparison, but many users search for one fixture at a time. The sections below summarize common DFU values for toilets, lavatory sinks, showers, tubs, kitchen fixtures, laundry fixtures, and floor drains.
Toilet DFU
A private-use toilet is commonly counted as 3 DFUs under UPC-style assumptions and 4 DFUs under IPC-style assumptions. Public-use toilets, flushometer fixtures, and local amendments may use different values.
For more detail, read the toilet DFU guide.
Lavatory Sink DFU
A lavatory sink is commonly counted as 1 DFU under both UPC-style and IPC-style assumptions. In a bathroom group, the lavatory may be reviewed together with the toilet, shower, or tub connected to the same branch.
Shower DFU
A standard shower is commonly counted as 2 DFUs under both UPC-style and IPC-style assumptions. Large showers, multi-head showers, linear drains, and unusual trap sizes may need closer review.
Bathtub or Tub-Shower DFU
A bathtub or tub-shower combination is commonly counted as 2 DFUs. The actual installation should still be checked for trap size, venting, branch drain layout, and local code requirements.
Kitchen Sink DFU
A kitchen sink is commonly counted as 2 DFUs. Dishwashers, garbage disposals, island sinks, indirect waste connections, and local plumbing amendments can affect how the kitchen group is reviewed.
Dishwasher DFU
A dishwasher is commonly counted as 2 DFUs in this planning chart. The discharge may connect through an air gap, disposal, sink tailpiece, or indirect connection depending on the project and local code.
Clothes Washer DFU
A clothes washer is commonly counted as 3 DFUs under UPC-style assumptions and 2 DFUs under IPC-style assumptions. Standpipe height, trap size, venting, and discharge rate should also be checked.
Floor Drain DFU
A floor drain is commonly counted as 2 DFUs in this planning chart. The final design may depend on the drain location, trap primer, indirect waste, garage or utility use, and local requirements.
Turn these fixture values into a total
After reviewing individual DFU values, use the DFU calculator to add fixture quantities and estimate the total drainage fixture-unit load for a bathroom, ADU, remodel, building drain, or sewer line.
How to use this DFU chart
- List every fixture connected to the drain or sewer.
- Choose the UPC or IPC column based on your jurisdiction.
- Multiply each fixture value by the number of fixtures.
- Add the line totals to estimate total DFUs.
- Compare the total against the correct code table for the actual pipe section.
What the chart does not tell you
A DFU chart does not determine pipe size by itself. The same DFU total can have different sizing implications depending on whether the pipe is a horizontal branch, vertical stack, building drain, or building sewer. Slope, developed length, venting, cleanouts, and local amendments can all change the final design.
Example DFU calculation
Here is a simple residential example using common UPC-style fixture values. Assume a small house, remodel, or ADU includes two private toilets, two lavatory sinks, two showers, one kitchen sink, one dishwasher, and one clothes washer.
Example using UPC values
- 2 private toilets × 3 DFU = 6 DFUs
- 2 lavatory sinks × 1 DFU = 2 DFUs
- 2 showers × 2 DFU = 4 DFUs
- 1 kitchen sink × 2 DFU = 2 DFUs
- 1 dishwasher × 2 DFU = 2 DFUs
- 1 clothes washer × 3 DFU = 3 DFUs
Total example load: 19 DFUs
The example total is useful for early planning, but it does not prove that every pipe is correctly sized. After calculating the fixture load, identify the pipe section being checked and verify the result against the adopted code table.
Common residential fixture groups
Many projects involve fixture groups rather than one fixture at a time. These simplified examples show how common residential groups can add up before you use a full calculator. For more detail, review the bathroom DFU guide and the toilet DFU guide.
Half bathroom
One private toilet plus one lavatory sink is commonly around 4 DFUs using UPC-style assumptions and around 5 DFUs using IPC-style assumptions.
Full bathroom
One private toilet, one lavatory, and one shower or tub-shower is commonly around 6 DFUs using UPC-style assumptions and around 7 DFUs using IPC-style assumptions.
Kitchen group
A kitchen sink and dishwasher are commonly around 4 DFUs. A garbage disposal, bar sink, ice maker, or commercial fixture may add load or change the installation details.
Laundry area
A clothes washer and laundry sink are commonly around 5 DFUs under UPC-style assumptions and around 4 DFUs under IPC-style assumptions.
UPC vs IPC fixture-unit differences
UPC and IPC fixture-unit values are similar for many common fixtures, but they are not identical. A private toilet, public toilet, urinal, or clothes washer may produce a different total depending on which code assumptions are used. These differences matter most when a project is close to a pipe sizing limit.
For example, a private toilet may be counted as 3 DFUs in UPC-style assumptions and 4 DFUs in IPC-style assumptions. That difference may not matter for a small bathroom, but it can matter when several bathrooms, an ADU, or a larger remodel all connect to the same building drain or sewer.
For a deeper comparison, read the UPC vs IPC plumbing code comparison.
How DFUs relate to pipe sizing
Once you total the fixture units, the next step is to identify the pipe section being checked. A branch drain, horizontal building drain, vertical stack, and building sewer can have different allowable loads. Pipe slope and orientation matter.
This is why a DFU chart should be used together with the correct code table and project layout. For common sizing questions, review the 3-inch pipe DFU guide and the 4-inch sewer capacity guide.
Planning shortcut: calculate fixture load first, then verify pipe size using the adopted plumbing code, pipe slope, pipe orientation, and actual layout.
Assumptions and limitations
- Values shown are planning values used for calculator and comparison purposes.
- Local amendments and code editions can change fixture-unit assignments.
- Public-use fixtures, commercial fixtures, flushometer fixtures, and indirect waste may need separate review.
- Pumped discharge, continuous flow, special equipment, and unusual trap sizes may require project-specific sizing.
- Final design should be verified with the authority having jurisdiction.
To check which code may apply in your area, start with the state plumbing code lookup.
Frequently Asked Questions
What is a DFU in plumbing?
DFU means drainage fixture unit. DFUs estimate the drainage load that plumbing fixtures add to a drain, branch, building drain, or building sewer.
What is a DFU chart?
A DFU chart lists common drainage fixture unit values for plumbing fixtures. Designers, plumbers, contractors, and owner-builders use DFU values to estimate drainage load before checking pipe sizing tables.
Do UPC and IPC use the same DFU values?
Not always. UPC and IPC both use drainage fixture units, but some fixture values and sizing assumptions differ. Toilets, urinals, clothes washers, and public-use fixtures are common places where the result may change.
How many DFUs is a toilet?
A private-use toilet is commonly estimated at 3 DFUs under UPC-style assumptions and 4 DFUs under IPC-style assumptions. Public-use toilets and flushometer fixtures may use different values.
How many DFUs is a full bathroom?
A basic full bathroom with one private toilet, one lavatory, and one shower or tub-shower is commonly around 6 DFUs using UPC-style assumptions and around 7 DFUs using IPC-style assumptions.
Can I size a pipe using a DFU chart alone?
No. A DFU chart helps estimate fixture load, but pipe sizing also depends on pipe diameter, slope, horizontal versus vertical orientation, developed length, venting, fixture grouping, and local amendments.
Should I use the UPC or IPC column?
Use the plumbing code adopted by the authority having jurisdiction for the project location. A state, city, county, or local building department may adopt UPC, IPC, a state plumbing code, or local amendments.
Important reminder
This DFU chart is for education and early planning only. Always verify drainage fixture unit values, pipe sizing, venting, cleanouts, materials, inspections, and permit requirements with the adopted plumbing code and local authority having jurisdiction before construction.
Need help turning fixture values into a DFU estimate?
Send your fixture list, quantities, project type, and whether you are using UPC or IPC assumptions. BuildCalc can help organize the fixture-unit estimate before you review pipe sizing.
Continue with DFU and pipe sizing resources
Use these related guides to estimate fixture loads, compare bathroom and ADU examples, check pipe sizing, and understand how DFUs affect drainage design.
DFU Calculator
Calculate drainage fixture units for common plumbing fixtures and estimate pipe sizing needs.
Toilet DFU Guide
Understand how toilets affect DFU totals, branch drains, building drains, and sewer sizing.
ADU Plumbing DFU Guide
Plan DFU loads for an accessory dwelling unit with bathroom, kitchen, laundry, and drainage fixtures.
Bathroom DFU Guide
Estimate total DFUs for bathrooms with toilets, lavatories, showers, tubs, and floor drains.
3-Inch Pipe DFU Capacity
Review typical DFU capacity considerations for 3-inch drain pipes, building drains, branches, and sewers.