How far can a toilet sit from the stack?
As a rule of thumb, up to about 10 feet (3 m) with a normal floor: plan the drain at 1/4 inch of fall per foot, twice the minimum the International Plumbing Code sets for a 3-inch pipe (1/8 inch per foot, IPC 2021 Table 704.1), and beyond about ten feet the drop starts to outgrow a normal floor.
Past that line you are choosing between a raised floor, a lowered ceiling below, or a macerator pump. Venting rules also tighten with distance, so the exact limit is a plumber question.
Why 10 feet
A 10 ft run at 1/4 inch per foot drops the pipe about 2.5 inches, which still fits inside a normal floor structure. Double the distance and the drain exits the bottom of the floor; that is the moment the project changes character. On a concrete slab the math is the same but the cutting is worse: see moving plumbing on a slab.
The planner watches the line for you
In the free bathroom planner you place the existing drain once; from then on every toilet position is checked against the distance line automatically, with the cost range alongside: what moving a toilet costs.
Frequently asked questions
What happens if I ignore the fall rule?
Too little slope and solids stay behind; too much and water outruns them, with the same result. Either way you have built a clog machine inside your floor. The code sets the minimum (1/8 inch per foot for a 3-inch drain, 1/4 inch for pipes of 2 1/2 inches or less, IPC 2021 Table 704.1, read 27 September 2026); planning at 1/4 inch leaves a margin.
Is a macerator toilet a good workaround?
It is a real option for a spot the gravity drain cannot reach: it grinds and pumps waste through a small line, even upward. The trade: noise, power dependence, maintenance, and local code limits. Good for a secondary bath, rarely first choice for the main one.
What does staying inside 10 feet save me?
Real money: a reroute of about 11 feet runs toward $2,680, and more on a slab, while a toilet near the stack moves almost for free. The planner warns the moment your layout crosses the line, before a contractor has to.