How to Replace a Toilet: Complete DIY Guide

Replacing a toilet is one of the most accessible plumbing DIY projects — it requires no special certifications, no soldering, and can be completed in two to three hours with basic tools. A new toilet costs $150–$600 for the fixture, and professional installation runs $150–$400, so DIYing it saves a meaningful amount. This guide covers every step from shutoff to final caulk.

This guide assumes a standard replacement where the new toilet uses the same 12-inch rough-in as the existing one. If you need to move the drain or change the rough-in distance, hire a licensed plumber.

Tools and Materials

Tools

Adjustable wrench
Channel-lock pliers
Hacksaw (for cutting old bolts if corroded)
Putty knife or scraper
Level
Bucket and sponge
Rags or old towels
Rubber gloves

Materials

New toilet (tank and bowl, or one-piece unit)
Wax ring (or wax-free gasket like a Fluidmaster Better Than Wax)
Toilet bolt set (if existing bolts are corroded)
Flexible braided stainless-steel supply line (if the old one is rigid or worn)
Silicone caulk (optional — for base-to-floor seal)
Shims (if the floor is uneven)

Total material cost (excluding toilet): $15–$40

Before You Start

Measure the rough-in — Measure from the wall (not the baseboard) to the center of the closet bolts on the existing toilet. Standard rough-in is 12 inches. Ten-inch and 14-inch rough-ins exist but are less common. Buy a toilet that matches your measurement.
Check the flange — If you can see rust, cracks, or damage on the closet flange when you look at the base of the current toilet, you may need a flange repair kit or a new flange. Severe flange damage is a job for a licensed plumber.
Buy the right supply line — Measure the distance from the shut-off valve to the toilet tank fill valve. A 12-inch braided supply line fits most installations.

Step-by-Step Installation

Step 1: Shut Off the Water and Empty the Tank

Turn the shut-off valve clockwise until it stops. Flush the toilet and hold the handle down to drain as much water as possible. Remove the tank lid and sponge out remaining water. Sponge the bowl water as well, or use a wet/dry vacuum.

Step 2: Disconnect the Supply Line

Place a towel or bucket under the connection. Use an adjustable wrench to disconnect the supply line from the tank’s fill valve. Some residual water will drip out.

Step 3: Remove the Old Toilet

Pop the caps off the closet bolts at the base of the toilet (one on each side).
Remove the nuts with an adjustable wrench. If the bolts spin freely, grip them with pliers while turning the nut. If they are corroded solid, cut them with a hacksaw.
Rock the toilet gently to break the wax seal, then lift the toilet straight up and off the bolts. Toilets weigh 50–80 pounds — lift with your legs, not your back. Have a helper if needed.
Set the toilet on an old towel or cardboard to protect the floor.
Stuff a rag into the open drain to block sewer gas and prevent objects from falling in.

Step 4: Inspect and Prepare the Flange

Scrape off the old wax ring with a putty knife. Remove all wax from the flange and the floor surface.
Inspect the flange — It should be level with or slightly above the finished floor. If it sits more than 1/4 inch below the floor, use a flange extender kit. If the flange is cracked, use a flange repair ring.
Insert new closet bolts into the flange slots, positioned evenly on each side.

If the flange is severely damaged, corroded through, or the floor around it is soft and spongy, stop and hire a licensed plumber. A compromised flange means the drain connection is not secure, which leads to leaks and sewage problems.

Step 5: Set the Wax Ring

Place the new wax ring (flat side down, tapered side up) onto the flange, centered over the drain opening. Alternatively, set it on the bottom of the toilet’s horn — whichever method you prefer. Wax-free gaskets (like Fluidmaster Better Than Wax) are reusable if you need to reposition the toilet — a significant advantage over traditional wax.

Step 6: Set the Toilet

Remove the rag from the drain.
Lift the toilet bowl and carefully lower it onto the flange, aligning the holes in the base with the closet bolts. This is the trickiest part — the bolts must thread through the holes while the horn seats into the wax ring.
Press down firmly with your body weight to compress the wax ring and seal the connection. Rock gently front to back and side to side to ensure full contact.
Do not lift the toilet once set — if you break the wax seal, you must replace the wax ring and start over (this is where wax-free gaskets shine).

Step 7: Secure and Level

Hand-tighten the closet bolt nuts, alternating side to side.
Use a wrench to snug the nuts — tighten in quarter-turn increments, alternating sides. Do not over-tighten — porcelain cracks easily. Stop when the toilet does not rock.
Check for level side to side. If the toilet rocks, use plastic toilet shims under the base. Trim excess shim material with a utility knife after tightening.
Cut excess bolt length with a hacksaw, leaving about 1/2 inch above the nut, then snap on the decorative bolt caps.

Step 8: Install the Tank (Two-Piece Toilets Only)

Place the rubber spud gasket on the flush valve at the bottom of the tank.
Set the tank onto the bowl, aligning the bolt holes.
Insert the tank bolts (with rubber washers on the inside of the tank) and tighten the nuts underneath. Alternate sides and tighten gradually — never over-tighten.
Verify the tank is level and does not wobble.

Step 9: Connect the Water Supply

Hand-thread the supply line nut onto the fill valve at the bottom of the tank.
Tighten with a wrench — hand-tight plus a quarter turn is sufficient for braided lines.
Connect the other end to the shut-off valve if you are using a new supply line.

Step 10: Turn On the Water and Test

Slowly open the shut-off valve.
Let the tank fill completely.
Flush 3–4 times, checking for leaks at every connection point: supply line, tank bolts, and the base where the toilet meets the floor.
Check for rocking — if the toilet moves at all, tighten the closet bolt nuts another quarter turn or add shims.

Step 11: Caulk the Base (Optional but Recommended)

Apply a bead of silicone caulk around the base where the toilet meets the floor, leaving a 2-inch gap at the back. This gap allows water from a potential wax ring failure to escape visibly rather than pooling under the toilet unseen.

Caulking the base is required by the International Plumbing Code (IPC Section 405.5) in many jurisdictions and prevents mop water and bathroom moisture from wicking under the toilet.

Troubleshooting

Problem	Cause	Fix
Toilet rocks side to side	Uneven floor	Add plastic shims and re-tighten bolts
Leak at base	Failed wax seal	Remove toilet, replace wax ring, reset
Leak at tank-to-bowl	Spud gasket misaligned	Loosen tank bolts, reseat gasket, retighten
Leak at supply line	Under-tightened or cross-threaded	Disconnect, re-thread carefully, tighten
Toilet runs continuously	Fill valve or flapper issue	See How to Fix a Running Toilet

When to Call a Plumber

Closet flange is broken, corroded, or more than 1/4 inch below the floor
Subfloor around the flange is soft or rotted
Drain pipe is damaged or corroded
You need to change the rough-in distance
You are relocating the toilet to a new position

Always hire a licensed plumber for drain or rough-in modifications.

Toilet Upgrade Guide: Features Worth the Money — Choosing the right toilet
Complete Bathroom Renovation Guide 2026 — Full renovation planning
Bathroom Plumbing Rough-In Guide — When rough-in changes are needed
Grout vs. Caulk Guide — Caulking techniques
Home Plumbing Guide — Understand your plumbing system

Bottom Line

Replacing a toilet is a straightforward DIY project that takes two to three hours and saves $150–$400 in labor. The keys are measuring the rough-in before buying, not over-tightening bolts on porcelain, and ensuring the wax ring makes a complete seal. If the flange or subfloor is damaged, call a licensed plumber — a few hundred dollars for professional repair is far cheaper than a sewage leak.

Sources: Angi 2026 toilet installation costs; International Plumbing Code (IPC) Section 405.5; HomeGuide 2026 toilet replacement pricing.