RoboPacer Watts
Calculator

Each RoboPacer rides at a fixed W/kg, so the watts you need scales directly with your weight — heavier riders need more absolute watts. On climbs, W/kg is the great equaliser and the relative effort is approximately the same for all riders. On flat routes it's more nuanced: heavier riders can hold the pacer's speed at a slightly lower W/kg than shown, while lighter riders typically need to push a little above it, because absolute watts matter more than W/kg when aerodynamic drag is the main force to overcome. Drafting (sitting in the slipstream of the group) also reduces your power demand by roughly 25–30%, so staying tucked in the bunch is notably easier than riding off the front.

Zwift models real-world physics, so gradients directly affect how hard you need to work. On a climb you'll need considerably more watts to hold the RoboPacer's wheel; on a descent you can ease right off. The W/kg ratings shown here reflect flat-road effort — use them as your baseline, and expect your power to rise and fall with the terrain.

Sofia (0.8 W/kg) and Taylor (1.1 W/kg) are the most accessible starting points. Sofia is perfect for recovery rides or anyone just getting started on Zwift. As your fitness builds, Bernie (1.5 W/kg) is a natural next step. Use this calculator to see the exact watts you'll need at your weight before committing to a ride.

W/kg stands for watts per kilogram — your power output relative to your body weight. Zwift sets RoboPacer speeds using W/kg because it creates a fair, consistent benchmark across riders of all sizes. A heavier rider needs more absolute watts to match the same W/kg as a lighter rider, but the road speed and physical effort are equivalent. That's exactly why this calculator converts the rating into the specific watts you need.

Yes! Any Zwift group ride or race listed with a pace (e.g. "2.5 W/kg ride") uses the same maths. Find your weight in the results table, look up the closest W/kg value, and use those watts as your target power. It's a quick way to know whether a listed ride is comfortably within your range or a stretch goal.

That's completely normal — the target watts shown here are what you need to hold the pacer's wheel, essentially the effort required to ride at the front of the group without a draft. During an actual ride, you'll spend most of your time sitting in the bunch behind the pacer and other riders, which reduces your power demand by roughly 25–30%. Add in descents where you can ease right off, and your average over a full session will naturally come in well below the target figure. Use the calculator's number as your benchmark for when you're working — not as a prediction of your average power.