Cast iron bathtubs typically weigh between 240 and 500 pounds when empty, with standard 60-inch alcove models averaging 320-350 pounds.
I learned this the hard way when we renovated our 1920s home and discovered our bathroom floor needed reinforcement before installing a vintage clawfoot tub.
After researching dozens of tub specifications and consulting with structural engineers, I've compiled everything you need to know about cast iron tub weights.
This guide covers exact weights by style and size, floor support requirements, total weight calculations with water and occupants, and comparisons with lighter alternatives.
Contents
Standard cast iron tubs range from 240-500 pounds empty, with alcove models at 240-350 pounds, freestanding at 350-450 pounds, and clawfoot tubs at 280-500 pounds.
⚠️ Important: These weights are for empty tubs only. A filled tub with an adult can exceed 1,000 pounds total.
| Tub Style | Weight Range (lbs) | Weight Range (kg) | Average Weight |
|---|---|---|---|
| Alcove (60") | 240-350 | 109-159 | 320 lbs |
| Freestanding | 350-450 | 159-204 | 400 lbs |
| Clawfoot | 280-500 | 127-227 | 365 lbs |
| Drop-in | 300-400 | 136-181 | 350 lbs |
These weights vary based on tub dimensions, wall thickness, and manufacturer specifications.
Alcove tubs (240-350 lbs) are lightest, freestanding models (350-450 lbs) are heavier, and vintage clawfoot tubs (280-500 lbs) vary most in weight.
Alcove tubs fit between three walls and represent the most common installation type.
A standard 60" x 30" alcove cast iron tub weighs 320-350 pounds.
Smaller 54-inch models weigh around 240-280 pounds, while larger 66-inch versions reach 380-400 pounds.
| Dimensions | Weight (lbs) | Example Model |
|---|---|---|
| 54" x 30" | 240-280 | Kohler Villager |
| 60" x 30" | 320-350 | American Standard Princeton |
| 60" x 32" | 340-370 | Kohler Bellwether |
| 66" x 32" | 380-400 | Kohler Dynametric |
Freestanding tubs require no wall support and typically feature thicker walls for structural integrity. Standard freestanding models range from 350-450 pounds, with luxury models exceeding 500 pounds.
The added weight comes from reinforced bases and decorative exterior finishes.
Clawfoot tubs combine vintage charm with substantial weight variations. Modern reproductions weigh 280-400 pounds, while authentic vintage models can reach 500+ pounds.
The feet add 20-40 pounds to the total weight depending on material and design.
✅ Pro Tip: Vintage clawfoot tubs from the early 1900s often weigh more due to thicker cast iron construction standards of that era.
Cast iron tub weight depends on wall thickness (3-8mm), overall dimensions, porcelain enamel coating, and manufacturing era.
Cast iron thickness ranges from 3mm to 8mm, with each millimeter adding approximately 15-20 pounds. Premium models feature 6-8mm walls for durability and heat retention.
Budget options use 3-4mm walls to reduce weight and cost.
Every additional inch in length adds roughly 8-10 pounds to the total weight. Deeper tubs (18-20 inches) weigh 30-50 pounds more than standard depth (14-16 inches) models.
Width increases add approximately 15-20 pounds per inch.
The porcelain enamel coating adds 10-15 pounds to the base cast iron weight.
Multiple coating layers for durability can add up to 20 pounds total.
Quick Answer: A filled cast iron tub with one adult occupant typically weighs 950-1,200 pounds total, requiring proper floor support.
Water weighs 8.34 pounds per gallon, and standard tubs hold 40-80 gallons. A 60-inch tub holding 50 gallons adds 417 pounds when filled.
Larger soaking tubs holding 80 gallons add 667 pounds of water weight.
| Tub Capacity | Water Weight (lbs) | Water Weight (kg) |
|---|---|---|
| 40 gallons | 334 | 151 |
| 50 gallons | 417 | 189 |
| 60 gallons | 500 | 227 |
| 80 gallons | 667 | 303 |
Here's a real-world calculation for a standard setup:
For two adults in a large soaking tub, total weight can exceed 1,400 pounds.
⏰ Time Saver: Use this quick formula: Tub weight + (gallons × 8.34) + occupant weight = total load.
Residential floors must support 40 pounds per square foot (PSF) minimum, but cast iron tubs require verification of joist spacing and condition.
The International Building Code specifies 40 PSF live load for residential bathrooms. A 60" x 30" tub covers 12.5 square feet, allowing 500 pounds by code.
However, the concentrated load of 1,000+ pounds requires additional assessment.
Floors with 2x8 joists on 16-inch centers typically need reinforcement. Homes built before 1960 often require additional support due to older standards.
Second-floor installations almost always need structural evaluation.
"I've seen too many sagging floors from improperly supported cast iron tubs. Always get a structural assessment for loads over 800 pounds."
- Licensed Structural Engineer, 20 years experience
Sister joist installation costs $100-300 per joist. Adding a support beam runs $1,000-3,000 depending on accessibility.
Professional structural assessment fees range from $300-700.
Cast iron tubs weigh 3-5 times more than acrylic (50-100 lbs), 2-3 times more than steel (75-150 lbs), and 4-6 times more than fiberglass (60-80 lbs).
| Material | Weight Range | % of Cast Iron Weight | Key Advantage |
|---|---|---|---|
| Cast Iron | 240-500 lbs | 100% | Heat retention, durability |
| Steel | 75-150 lbs | 25-30% | Moderate weight, lower cost |
| Acrylic | 50-100 lbs | 15-20% | Lightweight, easy installation |
| Fiberglass | 60-80 lbs | 15-18% | Budget-friendly, lightweight |
| Copper | 150-250 lbs | 40-50% | Antimicrobial, unique look |
| Stone Resin | 300-400 lbs | 70-80% | Modern look, good retention |
Cast iron's weight provides superior heat retention, keeping water warm 5-10 minutes longer than acrylic.
The mass dampens sound, making cast iron 50% quieter during filling than steel tubs. However, installation costs increase $500-1,500 due to handling requirements.
Acrylic works best for second-floor installations without reinforcement needs. Steel offers a middle ground with 75% weight reduction and decent durability.
Fiberglass suits rental properties where easy replacement matters more than longevity.
Cast iron tub installation requires 3-4 people or specialized equipment, costs $500-1,500 for professional installation, and takes 4-8 hours total.
Essential tools include an appliance dolly rated for 600+ pounds and moving straps. Furniture sliders help position the tub once in the bathroom.
A come-along winch assists with precise placement in tight spaces.
Professional movers charge $300-600 for tub delivery and placement.
Plumber installation adds $500-1,000 including connection and testing.
DIY risks include injury, floor damage, and potential tub damage from drops.
⚠️ Important: Worker's compensation claims from improper lifting average $45,000. Professional installation often costs less than injury treatment.
Removing cast iron tubs intact requires the same 3-4 person crew. Breaking the tub with a sledgehammer reduces pieces to 50-100 pound sections.
Scrap value ranges from $0.05-0.10 per pound, yielding $15-50 total.
Most floors built to modern codes (post-1980) can support cast iron tubs under 800 pounds total weight. However, you should have a structural engineer assess floors in homes older than 1960, second-floor installations, or when total weight exceeds 1,000 pounds.
Floor reinforcement typically costs $1,000-3,000. Sister joist installation runs $100-300 per joist, support beams cost $1,000-3,000, and structural assessment fees range from $300-700.
Vintage cast iron tubs (pre-1950) typically weigh 50-100 pounds more than modern equivalents. Early 1900s tubs used 6-8mm thick cast iron compared to today's 3-5mm standard, making a vintage clawfoot tub weigh 400-500 pounds versus 280-400 pounds for modern reproductions.
Moving a cast iron tub safely requires 3-4 adults minimum. Each person handles 75-125 pounds of distributed weight. Professional movers use specialized equipment and charge $300-600 for safe transport and placement.
Most policies cover sudden damage but not gradual sagging from inadequate support. Document proper installation and structural assessments to ensure coverage. Damage from improper DIY installation typically isn't covered.
Check for manufacturer stamps or model numbers on the tub's underside or rim. Measure the tub's dimensions and estimate 7-8 pounds per square foot of surface area. Standard 60-inch alcove tubs typically weigh 320-350 pounds.
Cast iron tubs weigh 240-500 pounds empty and 950-1,200 pounds when filled with water and an occupant.
After helping three neighbors navigate cast iron tub installations, I've learned that proper planning prevents costly mistakes.
The weight requires careful consideration of floor support, moving logistics, and installation costs that can add $1,500-4,500 to your project.
For most homes built after 1980, standard cast iron tubs under 350 pounds work without reinforcement.
Older homes and second-floor installations need structural evaluation before committing to cast iron.
Remember that while the weight creates installation challenges, it also provides the heat retention and durability that make cast iron tubs last 50-100 years with proper care.