Example Data Table
| Length |
Width |
Drain Position |
Drain Thickness |
Slope |
Waste |
Mix Ratio |
| 4 ft |
3 ft |
2 ft by 1.5 ft |
1.25 in |
0.25 in/ft |
10% |
5:1 |
| 5 ft |
4 ft |
2.5 ft by 2 ft |
1.50 in |
0.25 in/ft |
12% |
5:1 |
| 6 ft |
3.5 ft |
3 ft by 1.75 ft |
1.25 in |
0.30 in/ft |
15% |
4:1 |
Formula Used
Area = Length × Width.
Farthest run = distance from drain to farthest corner.
Rise = Slope × Farthest run.
Perimeter thickness = Drain thickness + Rise.
Average thickness = (Drain thickness + Perimeter thickness) ÷ 2.
Wet volume = Area × Average thickness.
Volume with waste = Wet volume × (1 + Waste ÷ 100).
Dry material volume = Volume with waste × Dry factor.
Sand volume = Dry material volume × Sand parts ÷ Total parts.
Cement volume = Dry material volume × Cement parts ÷ Total parts.
Bags = Required volume ÷ Bag yield.
How To Use This Calculator
Enter the shower length and width first.
Choose the dimension unit used on site.
Add the drain position from two nearby sides.
Enter the mud thickness planned at the drain.
Use the required slope in inches per foot.
Add waste for spills, trimming, and uneven mixing.
Enter your chosen sand to cement ratio.
Adjust bag weights, densities, and premix yield if needed.
Press calculate.
The result appears above the form.
Use CSV or PDF buttons for records.
Deck Mud Planning Guide
A deck mud bed looks simple, but planning matters. The bed must support tile, drain water, and keep a steady pitch. Small errors can create birdbaths near the drain. They can also leave weak thin areas near edges. This calculator helps estimate material before mixing starts.
Why Slope Matters
Shower deck mud normally needs a steady fall toward the drain. The common field target is one quarter inch per foot. A centered drain gives balanced slopes. An offset drain makes one side steeper when the perimeter stays level. That is why drain location is included.
Thickness And Volume
The calculator starts with the drain thickness. It finds the farthest corner from the drain. Then it raises the perimeter by the selected slope. The average thickness is used for volume. This method gives a practical planning value for rectangular shower pans.
Mix Ratio Control
Deck mud is usually a dry pack blend. Many installers use five parts sand and one part cement. Some jobs need a richer four to one blend. The calculator lets you change both parts. It separates sand and cement volume from the total dry material.
Waste And Dry Factor
Real mixing is not perfect. Material stays in buckets. Some mud is dropped or trimmed. Dry ingredients also lose volume after water is added and packed. The waste percentage and dry factor cover these losses. Keep them realistic, especially on large pans.
Bag Estimates
Bag counts depend on yield. Cement, sand, and premixed products vary by supplier. Use the label on the bag when available. Change weight, density, and premix yield to match your product. Always buy a little extra. A short mix can stop the job at the worst time.
FAQs
What is deck mud?
Deck mud is a dry pack mortar. It usually contains sand, cement, and limited water. It is packed and shaped to make a sloped shower base.
What slope should I use?
A common shower floor target is one quarter inch per foot. Local rules, drain type, and tile layout may require different values.
Why does drain position matter?
An offset drain changes the farthest run. A level perimeter then creates steeper slopes on shorter sides. This affects thickness and comfort.
What mix ratio is common?
A five to one sand and cement ratio is common for dry pack. Some installers use four to one for a richer blend.
Why add a dry material factor?
Dry ingredients compact after water is added and packed. The dry factor helps estimate enough loose material before mixing.
Should I use premixed bags?
Premixed deck mud is convenient for small jobs. Check the bag yield and enter it here. Product yields vary by brand.
Does this replace field judgment?
No. It is an estimating aid. Check substrate, drain height, waterproofing method, and tile requirements before placing mud.
Why buy extra material?
Extra material covers waste, low yields, uneven floors, and mixing loss. Running short can cause cold joints and poor packing.