How to Install a Toilet (Complete Guide)

Installing a toilet is one of the highest-value DIY plumbing jobs you can do. A plumber typically charges $200-400 in labor alone to swap out a toilet, and the work takes about one to two hours. If you can tighten bolts and follow directions, you can do it yourself. This guide walks you through every step — removing the old toilet, prepping the flange, setting the new bowl, and testing for leaks.

Before You Start: Choosing the Right Toilet

Most residential toilets use a standard 12-inch rough-in, which is the distance from the wall to the center of the floor bolts. Measure yours before buying. A 10-inch or 14-inch rough-in exists in some older homes, and buying the wrong size means a return trip to the store.

For the toilet itself, look for a WaterSense-certified model rated at 1.28 gallons per flush (GPF). Two-piece toilets (separate tank and bowl) are easier to carry and install. One-piece models look sleeker but weigh 80-100 pounds, which makes solo installation harder.

Tools and Materials You Will Need

Tools:

Adjustable wrench
Channel-lock pliers
Putty knife or paint scraper
Hacksaw (if old bolts are corroded)
Level
Bucket and sponge
Old towels or rags
Disposable gloves

Materials:

New toilet (bowl, tank, seat, and hardware — most come as a kit)
Korky wax ring with flange (or a wax-free alternative like the Fluidmaster Better Than Wax ring)
New closet bolts (also called T-bolts) — 5/16-inch x 2 1/4-inch is standard
Flexible braided stainless steel supply line (12-inch length covers most setups)
Shims (composite, not wood — wood rots)
Tube of 100% silicone caulk (the same type used to caulk a bathtub)

Total materials cost beyond the toilet itself: roughly $15-25.

Step 1: Remove the Old Toilet

Shut Off the Water

Locate the shut-off valve on the wall behind and below the toilet. Turn it clockwise until it stops. Flush the toilet to drain the tank. Hold the lever down to get as much water out as possible.

Drain Remaining Water

Use a sponge and bucket to soak up the water left in the tank and bowl. There is always more water in there than you think. Lay old towels around the base to catch drips.

Disconnect the Supply Line

Use your adjustable wrench to unscrew the supply line nut where it connects to the bottom of the tank. Have the bucket underneath — some water will come out. If the existing supply line is rigid chrome or plastic, plan to replace it with a braided stainless steel line.

Remove the Tank (Two-Piece Toilets)

If your toilet has a separate tank, remove it first to make the bowl lighter and easier to handle. Unscrew the two or three tank bolts on the underside of the tank with your adjustable wrench while holding the bolt head inside the tank with a screwdriver. Lift the tank straight up and set it aside.

Remove the Bowl

Pop off the decorative caps covering the closet bolts at the base. Use your adjustable wrench to remove the nuts. If the bolts spin freely or are rusted solid, cut them with a hacksaw.

Rock the bowl gently side to side to break the wax seal, then lift straight up. Toilets are heavy — 50-60 pounds for a bowl alone. Lift with your legs, not your back. Set the old toilet on a garbage bag or cardboard to catch the residual wax.

Plug the Drain

Immediately stuff a rag into the open drain hole (the flange opening). This keeps sewer gas from coming into the room and prevents you from dropping anything down the pipe.

Step 2: Prep the Flange

Scrape all the old wax off the flange and the floor with your putty knife. Get it clean. Old wax left behind will prevent the new ring from sealing properly.

Inspect the flange carefully:

Flange is flush with or slightly above the finished floor: Good. You are ready to go.
Flange sits below the finished floor (common after new flooring is installed): Use a flange extender or an extra-thick wax ring to bridge the gap. The Korky wax ring with the built-in polyethylene flange works well here.
Flange is cracked or broken: Stop here and read the “When to Call a Pro” section below.

Install new closet bolts into the flange slots. Slide them into the keyhole openings and rotate them 90 degrees so they lock in place. Make sure they are evenly spaced and pointing straight up.

Step 3: Install the New Toilet

Place the Wax Ring

Turn the new bowl upside down on a soft surface (cardboard works). Press the wax ring firmly onto the horn — the round outlet on the bottom of the bowl. The tapered polyethylene sleeve, if your ring has one, should point away from the bowl (toward the drain).

Some people prefer to set the wax ring on the flange instead. Either method works, but placing it on the bowl gives you better visibility and alignment.

Important: You get one shot with a wax ring. Once it compresses, you cannot reposition it. If you set the bowl and it does not feel right, you need a new wax ring.

Set the Bowl

Remove the rag from the drain hole. Lift the bowl and carefully lower it over the closet bolts, using the bolts as guides. The bolts should come up through the holes at the base of the bowl.

Press the bowl down firmly with even pressure — sit on it if needed — to compress the wax ring and create a seal. Do not rock the bowl side to side, as this can deform the wax ring and cause leaks.

Tighten the Closet Bolts

Place a washer and nut on each closet bolt. Tighten them by hand first. Then use your wrench to snug them down, alternating between sides — a few turns on the left, then a few on the right. This keeps the bowl centered and applies even pressure on the wax ring.

Do not over-tighten. Porcelain cracks easily. Tighten until the bowl does not rock, then stop. If the bowl wobbles because of an uneven floor, use composite shims under the base. Trim the shims flush with a utility knife after installation.

Once tight, cut the excess bolt length with a hacksaw (leave about 1/2 inch above the nut) and snap on the decorative caps.

Attach the Tank (Two-Piece Toilets)

Place the rubber spud gasket onto the flush valve opening on the bottom of the tank (it usually comes pre-installed). Set the tank onto the bowl, aligning the bolt holes. Insert the tank bolts with rubber washers through the holes from inside the tank.

From underneath, hand-tighten the nuts. Then alternate sides with a wrench, just like the closet bolts. Snug — not gorilla-tight. The rubber gasket does the sealing, not brute force.

Connect the Water Supply

Thread the supply line onto the fill valve at the bottom of the tank. Hand-tighten, then give it a quarter-turn with your wrench. Connect the other end to the shut-off valve the same way.

Test for Leaks

Turn on the shut-off valve slowly. Let the tank fill completely. Flush a few times and watch every connection point:

Base of the bowl: Water here means the wax ring is not sealed. You will need to pull the bowl and start over with a new wax ring.
Tank-to-bowl connection: Tighten the tank bolts slightly. If still leaking, check that the spud gasket is seated correctly.
Supply line connections: Usually just needs a slight snug at the fitting.

Run a piece of dry paper towel along each connection. It will show even the smallest drip.

Caulk the Base

Once you have confirmed there are no leaks, apply a bead of silicone caulk around the base of the toilet where it meets the floor. Leave a small gap at the back — this acts as a weep hole that will alert you to a future wax ring failure before water damages your subfloor.

Let the caulk cure for 24 hours before heavy use.

Common Mistakes to Avoid

Over-tightening bolts. This is the number-one mistake DIYers make. Porcelain is not forgiving. Tighten evenly and stop when the bowl or tank is snug. One extra quarter-turn can crack the base and ruin a $200 toilet.

Skipping the wax ring. It sounds absurd, but it happens — especially when people rush. No wax ring means sewer gas and water will leak from under the bowl every time you flush.

Not checking the flange height. If the flange sits too low, a standard wax ring will not make contact. You will get a slow leak that damages the subfloor before you even notice it.

Using the old supply line. Rigid chrome supply lines fatigue over time. A new braided stainless steel line costs $8 and gives you years of worry-free service.

Rocking the bowl after setting it. Once the bowl is on the wax ring, press straight down. Rocking smears the wax and breaks the seal.

Forgetting to level. A toilet that wobbles will eventually break its wax seal. Shim the base before tightening the bolts, not after.

When to Call a Pro

Most toilet installations are straightforward, but some situations call for a licensed plumber:

Cracked or broken flange. A toilet flange repair requires cutting pipe and solvent-welding a new flange. It is doable as DIY, but mistakes here cause major water damage.
Lead or cast iron drain pipes. Older homes sometimes have lead bends or cast iron drains that are corroded or fragile. Disturbing these without experience can create bigger problems.
Subfloor damage. If the floor around the flange feels soft or spongy, there is likely water damage or rot underneath. This needs to be repaired before a new toilet goes in.
Moving the toilet to a new location. Relocating a toilet means rerouting the drain, which involves cutting into the floor and modifying the waste line. This is permit-required work in most municipalities.

Cost Breakdown: DIY vs. Hiring a Plumber

	DIY	Professional
Toilet	$150-400	$150-400
Wax ring, bolts, supply line	$15-25	Included in labor
Labor	$0 (your time)	$200-400
Total	$165-425	$350-800

You save $200-400 by doing it yourself, and the job takes one to two hours on your first attempt. Your second install will take half that.

Final Checklist

Before you call it done, run through these checks:

Flush three times and watch for leaks at the base, tank connection, and supply line.
Check that the bowl does not rock or move.
Confirm the water level in the tank sits about one inch below the overflow tube.
Verify the toilet fills and stops — no running water sound after the tank is full. If the toilet keeps running, see how to fix a running toilet.
Make sure the caulk bead is smooth and complete around the base (with a gap at the back).

That is it. You now have a properly installed toilet that should serve you well for 20-plus years. The money you saved on plumber fees just paid for your next project. If you are renovating the full bathroom, check out our bathroom remodel cost breakdown to plan your budget.