How the planner works

The planner splits a Zwift route into intervals by gradient and gives each one a power target. It simulates the ride with your weight, height, bike and the road surface, and tracks your W' balance (your anaerobic reserve) along the way. Optimise searches for the fastest set of targets that never lets your W' balance drop below your floor: it puts power where it buys the most time, mostly climbs and slow sections, and takes it off where it buys the least, mostly descents. W' is assumed to refill no faster than the power you hold back below CP.

Set up the rider and the course

Rider: Look up your Zwift ID to fill in your weight, height and FTP, or type them. Looking up also brings your 90-day power curve, which the planner uses to estimate your W' and, when the curve is good enough, your critical power (CP).
W': The work you can do above CP before you have to ease off, in kilojoules. Most riders are between 12 and 25 kJ. The planner suggests one and says how sure it is: good estimate when it is fitted to your own power curve, fair estimate when it has less to go on, rough guess when it only has your weight. If you know yours, type it in; the Use button next to the suggestion goes back to it.
Course: Choose the route, then laps or a set distance, and the bike you will race on: frame, wheels and upgrade level as Zwift names them, and aero socks if you wear them. The default is a Cadex Tri at level 5 on Cadex 4-Spoke Disc wheels; some events fix the bike (pick the CTT bike for CTT races) or turn upgrades off (level 0). The lead-in to the start banner is part of the plan. Bike data from Zwift Speed Lab and zwifttools, checked against ZwiftInsider's speed tests.
Find the fastest bike: Rides your plan's powers on the bikes that could be fastest on the course and shows two short tables: the five fastest frames, each on its fastest wheels, and the five fastest wheels for your frame, each stock (level 0) and fully upgraded (level 5), with your own bike at the foot and the time against your plan. Your upgrades are your own, bike by bike, so yours fall between the two levels. Pick a frame to put it beside your plan, where you can set the level you have; pick wheels to ride your plan on them. Bikes that ride exactly alike (the same frame in another paint, for one) share a row. It runs only when you ask. When you plan an event that allows no TT bikes it lists none; other event rules (a fixed bike, upgrades off) are not taken into account. Gravel and mountain bikes appear only where the course has gravel or dirt; handcycles and recumbents never.

Once both are set they fold down to one line each. Change opens them again.

Read the plan

The large number is the finish time. Next to it: average and normalised power, the lowest your W' balance gets, and how much faster the plan is than riding the same course at one steady power. The label says what kind of plan you are looking at:

Draft: Built from your settings and rebuilt whenever you change one.
Optimised: The result of Optimise. It is never rebuilt behind your back: if you change a setting afterwards it says settings changed and offers to re-optimise.
Edited: You changed an interval. Settings that change how the plan rides (W', bike, floor) re-time your intervals; anything else asks before replacing them.

Choose how hard to go

Strategy: Fastest spends your reserve down to the floor. Balanced and Safe keep more of it in hand for a cleaner finish. After Optimise, Compare strategies shows all three with their times.
Floor: The slider beside the chart sets the lowest W' balance the plan may reach. Raise it above zero to keep something back.
Race-day margin: Paces the plan for a rider a few percent below your numbers (both CP and W'), for a day that is not your best or a trainer that reads high. The powers come down and you keep W' in hand: the headline shows the W' you would really have left, then what is left on a day that much down (the dashed line on the chart). Changing it re-optimises an optimised plan; an edited plan keeps your powers and offers Re-optimise.
Power: Raises or lowers every target in the finished plan, by up to 10%. Use it when you know you are better than your numbers (you have trained well but not ridden flat out), or to take a plan down a notch. The plan is still built from your CP and W' as you set them, and Optimise still works to your floor; Power is applied afterwards, so your W' balance shows what the extra costs. Over 100% it will go below your floor, and a note says by how much. The headline says when targets were moved this way. To change the numbers the plan is built from, change your FTP or W' in the rider setup instead.

Change the plan

Type a new power in the table, or a new end distance to move the boundary between two intervals.
Split cuts an interval in half; Merge joins it to the next one.
Switch the chart to Edit to drag power bands up and down and boundaries sideways.
Undo and Redo step through your edits and through Rebuild and Optimise. Reset to optimised goes back to the plan from your last Optimise.

A note under the headline tells you if an edited plan takes your W' below the floor, and if any plan asks for more than your best power for that long in the last 90 days. Optimise does not hold a plan to that best: a power curve shows what you happened to ride, not all you can do. Treat such a plan as a stretch target, or lower Power.

Ride it

The Race HUD guide walks through riding a plan in Zwift with the Sauce4Zwift mod, step by step with pictures.

Race overlay opens the plan in a second window to follow during the race. Its link carries the plan's code, so it also works in OBS or on another device.
Link Sauce (in Share) once, with the pairing code the Sauce4Zwift mod shows under settings → Plans, and the plans you optimise here reach the HUD by themselves, within a minute, while it is open and no race is running. The dialog says Sauce has it ✓ when the mod has saved the plan. No key to make or copy: the link is the credential, and either side can end it.
Upcoming time trial (under Course) lists the next seven days of time trials and no-draft rides. Choosing one sets the route, the laps or the distance, and the plan knows its event: when you join that event's pen, the HUD arms the plan by itself. Plan this event optimises in one click. In the HUD, Plan it does the same from the bike for the event you are in or signed up for, with your last planner settings.
Share gives a six-character code and a QR code. The code loads the plan in the planner, the overlay and the mod on another device. Codes last seven days. Use the mod's latest release: older versions still load the plan but change targets only once you reach each one, with no warning, and work out W' from your FTP.
Export saves the plan as a plan file (open it later with Load a plan; it does not expire), copies the interval table as text, saves an image of the plan, saves an ERG workout to practise the pacing in Zwift, or saves the route itself as GPX, without power targets.

Advanced settings (under the chart)

Training level: How well you hold power over a long effort, and how quickly W' recovers when you ride below CP.
Start: Fast start rides the first minute at least 10% over your CP. Automatic and Steady leave it to the optimiser, which rarely gains from a fast start.
Finish: Save some for the end holds back a quarter of your W' until the last tenth of the course, then plans to spend it there. Automatic and Even spend it wherever it saves the most time.
Power changes: How big a step from one interval to the next may be, and how much time a change has to save to be worth it: Few and small keeps steps under about 15% of FTP, Normal under about 35%, Larger if they save time has no limit and may stop pedalling on fast descents.
Compare with another bike: Rides the same powers on a second bike and draws the time gap on the chart. It starts as your bike: change the frame, wheels, level or socks to see what that part is worth on this course.
Speed model: By default the bike carries momentum: it speeds up and slows down gradually, as in Zwift. Checked against two CTT races (every finisher), it is within about half a percent of the real times on flat and hilly courses. Turned off, speed settles at each gradient straight away, which is close on the flat but minutes slow on a hilly course.

Good numbers in, good plan out

An FTP that is too high gives a plan you cannot hold; too low leaves time on the road. The same goes for W': too high and the plan asks for surges you cannot repeat, too low and it is too cautious on the climbs. Weight and height change the speed on climbs and on the flat. Use a recent test or race, and your real weight.