Quick Answer: Peloton calculates power (Output) by measuring cadence (RPM) and resistance (0-100). The bike's computer uses a factory-calibrated power curve to convert these metrics into Watts. While the original Bike estimates power based on a lookup table, the Bike+ utilizes an advanced digital control system that provides more consistent measurements across a wider range of conditions.
Table of Contents
- What is Power (Output) on a Peloton?
- How the Peloton Resistance System Works
- The Power Calculation Formula
- What Calibration Actually Does
- Peloton Bike vs Bike+ Power Measurement
- How Accurate is Peloton Power?
- Peloton Power vs Outdoor Power Meters
- Why Your Output Changes Over Time
- Frequently Asked Questions
What is Power (Output) on a Peloton?
Power is the rate at which you do work, measured in watts. On a Peloton, the screen displays this as "Output" — it's the same thing as watts, just branded differently. When you see 150 output on your screen, you're producing 150 watts of power.
It's important to distinguish Output from Peloton's Strive Score: * Output (Watts): Measures the physical work done on the bike (mechanical energy). * Strive Score: Measures your heart rate effort (metabolic energy).
Power matters because it's the most objective measure of cycling effort. Heart rate lags behind effort, perceived exertion is subjective, and speed doesn't apply on a stationary bike. Watts tell you exactly how hard you're working right now.
The Three Key Metrics
Your Peloton displays three interconnected numbers:
- Cadence (RPM) — How fast your legs are spinning. Measured directly by a sensor detecting flywheel rotation.
- Resistance (0-100) — How hard it is to pedal. Controlled by magnets that create braking force on the flywheel.
- Output (Watts) — How much power you're producing. Calculated from cadence and resistance using an internal formula.
The relationship is straightforward: spin faster or push harder (or both), and your output goes up.
How the Peloton Resistance System Works
Understanding how power is calculated starts with understanding how resistance works.
Magnetic Eddy Current Braking
Peloton doesn't use friction pads like older exercise bikes. Instead, it uses magnetic eddy current braking — the same technology used in roller coasters and high-speed trains.
Here's how it works:
- You pedal — This spins the 38-pound (17 kg) steel flywheel via a belt drive
- Magnets surround the flywheel — Permanent magnets are positioned near the rim of the flywheel
- Moving metal through a magnetic field generates eddy currents — These are circular electrical currents induced in the flywheel's steel
- Eddy currents create opposing magnetic fields — This produces a braking force that resists the flywheel's rotation
- Closer magnets = stronger braking — When you turn the resistance knob, you move the magnets closer to or farther from the flywheel
The key advantage of this system is zero contact. Nothing wears down, there's no dust, and resistance is smooth and silent. The downside is that the braking force depends on the speed of the flywheel — at very low cadences, even maximum resistance produces less force than at high cadences.
The Resistance Knob (Original Bike)
On the original Peloton Bike, turning the resistance knob physically moves a magnet assembly closer to or farther from the flywheel. A position sensor detects the knob's position and maps it to a 0-100 scale.
The mapping isn't linear. The difference between resistance 30 and 40 is much smaller than the difference between 60 and 70. This is because the magnetic braking force increases exponentially as the magnets get closer to the flywheel.
The Motorized Resistance (Bike+)
The Bike+ adds a motorized resistance system to the existing magnet assembly. The physical resistance knob still exists, but it acts as a digital encoder. When you turn it, you're sending a signal to a small electric motor that precisely adjusts the magnet position. This enables software-driven features like Auto-Follow in Peloton classes and ERG mode through FitSwitch.
The motor allows for more repeatable positioning than a manual system, which contributes to the Bike+'s reputation for higher consistency and accuracy.
The Power Calculation Formula
Peloton calculates power using a lookup table (also called a power curve) rather than a simple mathematical formula. Here's how it works.
The Power Curve
During manufacturing, each bike model (not each individual bike) has a power curve established through laboratory testing. This curve maps every combination of resistance level and flywheel speed to a specific wattage.
Think of it as a giant spreadsheet:
| Resistance | 60 RPM | 70 RPM | 80 RPM | 90 RPM | 100 RPM |
|---|---|---|---|---|---|
| 30 | ~45W | ~58W | ~72W | ~88W | ~105W |
| 40 | ~65W | ~82W | ~100W | ~122W | ~145W |
| 50 | ~95W | ~120W | ~150W | ~185W | ~220W |
| 60 | ~135W | ~170W | ~215W | ~265W | ~320W |
These values are approximate community benchmarks for a properly calibrated bike. Peloton's actual power curve is proprietary.
The Calculation Process
Every fraction of a second, the bike:
- Reads the cadence sensor — Determines current flywheel RPM
- Reads the resistance sensor — Determines current magnet position
- Looks up the power curve — Finds the corresponding wattage for that resistance + RPM combination
- Applies calibration offsets — Adjusts for your bike's specific calibration data
- Displays the result — Updates the output number on screen
(Advanced users can see these raw metrics and internal sensor readings by enabling Peloton Developer Mode).
This happens fast enough that the power reading feels instantaneous. The display updates multiple times per second.
Why It's Not a Simple Formula
You might expect power to equal resistance times cadence, but the physics of magnetic braking are more complex:
- Braking force scales with speed — At higher RPMs, the same magnet position creates more resistance
- The relationship is nonlinear — Doubling resistance doesn't double power
- Temperature affects magnets — Though Peloton doesn't dynamically compensate for this
- Flywheel momentum matters — A spinning flywheel stores energy, and the power reading accounts for net energy transfer
The power curve captures all of these physical relationships in a pre-computed table, avoiding the need for real-time physics calculations.
Total Output and Kilojoules
Your ride summary shows "Total Output" in kilojoules (kJ). This is simply watts integrated over time:
Total Output (kJ) = Average Power (watts) x Time (seconds) / 1000
A 30-minute ride averaging 150 watts produces: 150 x 1800 / 1000 = 270 kJ
For a useful rule of thumb, kilojoules roughly equal calories burned (within about 20-25%), because the human body is approximately 20-25% efficient at converting metabolic energy into mechanical work.
What Calibration Actually Does
Calibration is the process of telling your specific bike's software exactly where the magnets are at each resistance level.
The Calibration Problem
Every bike comes off the assembly line slightly different. The magnet assembly might sit 0.5mm closer or farther from the flywheel. The resistance knob's position sensor might read slightly differently. The belt connecting the pedals to the flywheel has slightly different tension.
Without calibration, the bike uses the generic power curve from the factory. But if your bike's magnets are 1mm closer to the flywheel than the reference bike used to create the power curve, then at resistance "50" your bike is actually producing the force that the reference bike produces at resistance "55." Your output numbers would be inflated.
What Happens During Calibration
On the Bike+:
The Bike+ is designed to be much more autonomous. Every time you turn the bike on or the system wakes from sleep, you may hear the resistance motor "whirring"—this is a hidden home-position calibration where the magnets find their zero-point.
For a full recalibration (Settings > Device Settings > Home Installation > Recalibration):
- The motor sweeps the magnets from minimum to maximum position
- Sensors measure the exact magnet position at each resistance level
- The software builds a correction table mapping knob position to actual magnet distance
- This correction table adjusts the power curve lookup to match your specific bike
On the Original Bike:
Peloton support provides a calibration procedure that:
- Has you set the resistance knob to specific positions (0 and 100)
- The software records the sensor readings at each endpoint
- It interpolates the positions in between
- The correction table is stored for power calculations
Why Post-Calibration Reboot Matters
After calibrating, you need to power cycle the bike (power off, unplug, wait 30 seconds, plug back in). The calibration data is written to persistent storage, but the running system may still use cached values. A full reboot forces the system to reload from the updated calibration data. For full calibration instructions, see our guide on how to calibrate your Peloton.
Peloton Bike vs Bike+ Power Measurement
The two Peloton models measure power differently.
Comparison Table: Power Measurement
| Feature | Original Peloton Bike | Peloton Bike+ |
|---|---|---|
| Measurement Method | Lookup Table (Estimated) | Lookup Table (Motor-Assisted Precision) |
| Resistance Control | Manual Knob | Motorized Magnet Control |
| Consistency | Moderate (Manual) | High (Software Controlled) |
| Calibration | Manual Calibration Kit | Automated Self-Calibration |
Original Peloton Bike
- Resistance control: Manual knob with position sensor
- Cadence measurement: Magnetic pickup sensor on flywheel
- Power calculation: Lookup table based on knob position + RPM
- Calibration: Requires contacting Peloton support or using a specialized plastic calibration tool.
- Accuracy: Subject to more variance due to mechanical tolerances in the manual knob assembly.
The original Bike relies entirely on a sensor reading the knob's location. Any play or looseness in the knob mechanism can introduce measurement error over time.
Peloton Bike+
- Resistance control: Motorized system with precise positioning
- Cadence measurement: Magnetic pickup sensor on flywheel
- Power calculation: Advanced digital calculation using motorized magnet positioning.
- Calibration: Built-in self-calibration in settings - no tools required.
- Consistency: Generally more repeatable because the motor can position magnets with sub-millimeter precision.
The self-calibration routine can be run anytime you notice output drift, ensuring the bike stays aligned with its factory power curve without manual intervention.
Hardware Variance Between Bikes
Peloton acknowledges that manufacturing tolerances mean two bikes can vary in output at the same resistance and cadence. While calibration corrects for each bike's unique hardware, it doesn't eliminate all physical differences between machines. This is a primary reason why comparing Peloton output to outdoor power requires nuance.
How Accurate is Peloton Power?
Peloton power accuracy has two components: internal consistency and absolute accuracy.
Internal Consistency (Repeatability)
On a properly calibrated bike, Peloton power readings are reasonably consistent. If you ride at resistance 45 and 85 RPM today, you should get a similar output number tomorrow. This is what matters for tracking your fitness over time on your own bike.
Community benchmarks suggest Peloton output is repeatable within a small margin on the same bike after calibration.
Pro-Tip: Output Consistency vs. Accuracy For training purposes on your own bike, internal consistency matters more than absolute accuracy. Your power zones, PR tracking, and fitness trends are all relative to your bike's measurements. If you're slightly high but consistently high, your training targets will still work perfectly.
Absolute Accuracy (vs Power Meters)
When compared against laboratory-grade power meters, Peloton readings show more variance:
- Well-calibrated Bike+: Generally stays closer to reference power meters due to motorized consistency.
- Original Bike: Can vary from reference depending on calibration state and age of the hardware.
- Uncalibrated bikes: Can be off by a significant margin in either direction.
Where FitSwitch Helps
FitSwitch reads power data directly from the Peloton's internal sensors and broadcasts it via FTMS to external apps and devices. This enables users to bridge Peloton hardware with professional training software:
- Seamless Training: Apps like Zwift, TrainerRoad, and Garmin devices receive the same power data your Peloton screen displays.
- Structured Power Zones: Because the data is identical to your Peloton screen, your training zones in Zwift will match your Peloton classes.
- Direct Data: FitSwitch uses the bike's own internal metrics. This means if you properly calibrate your bike, your external training data will be as consistent as your Peloton workouts.
Peloton Power vs Outdoor Power Meters
If you ride outdoors with a power meter, you've probably wondered how Peloton watts compare.
Different Measurement Methods
Outdoor power meters (like those from Stages, Quarq, or Garmin) measure actual force applied to the pedals, crank, or hub using strain gauges. They directly measure torque and multiply it by angular velocity to calculate watts.
Peloton estimates power indirectly from magnet position and flywheel speed. It never directly measures the force your legs apply.
This fundamental difference means the two will never match perfectly. They're measuring related but different things.
Common Observations
Riders who compare both typically find:
- Peloton reads 5-15% higher than outdoor power meters for most riders
- The gap increases at higher power — The nonlinear magnetic braking curve tends to overestimate at high resistance
- Low-cadence power is less accurate — Magnetic braking is weakest at low flywheel speeds, making power estimation less reliable below 60 RPM
- Calibration significantly affects the comparison — A well-calibrated Bike+ gets much closer to outdoor power meters than an uncalibrated original Bike
Should You Care About the Difference?
For most Peloton riders, no. What matters is that your numbers are consistent on your bike so you can track progress. Your Peloton FTP doesn't need to match your outdoor FTP — they're different tests on different equipment.
If you use FitSwitch to train with Zwift or TrainerRoad, take your FTP test on the Peloton with the same app you'll train with. This ensures your power zones are calibrated to the measurements your bike actually produces.
Why Your Output Changes Over Time
If your numbers drop or jump without a change in fitness, it's almost always a calibration or hardware issue — not you.
Common Causes
- Natural calibration drift — Vibrations from riding gradually shift magnet positions and loosen sensor alignment. This is the most common cause and can happen over months of regular riding.
- Mechanical Maintenance — It is common for loose crank arms or pedals to cause a clicking sound. While this may not directly change the electronic power calculation, it can affect the pedaling sensation and your ability to maintain a steady cadence, potentially impacting your overall output. Tighten these with a 15mm wrench (pedals) and 8mm hex (cranks).
- Temperature changes — Magnetic field strength varies with temperature. A bike in a cold garage will feel different from one in a heated room.
- Software updates — Peloton occasionally adjusts their power curve algorithm. Small output changes after an update may be intentional recalculations.
- Hardware wear — The drive belt stretches over time, changing the relationship between pedal speed and flywheel speed. Worn bearings add friction that the power calculation doesn't account for.
- Service visits — Technicians may disturb the magnet assembly or sensor positions during repairs.
What to Do About It
If your output changes noticeably (more than 10-15%):
- Recalibrate — Follow the steps for your bike model in our calibration guide
- Power cycle after calibration — Unplug for 30 seconds
- Do a benchmark ride — 40 resistance at 80 RPM should produce roughly 80-100 watts
- If still off, check hardware — Worn belts, loose sensors, or failing magnets need Peloton service
For Bike+ owners using FitSwitch for ERG mode or SIM mode, keeping calibration accurate is especially important. ERG mode targets specific wattage, and inaccurate power measurement means you're not hitting the training stimulus you think you are.
Frequently Asked Questions
Is Peloton output the same as watts?
Yes. "Output" is Peloton's term for power in watts. When the screen shows 200 output, you're producing 200 watts. Total output for a ride is measured in kilojoules, which is watts multiplied by time.
Does Peloton have a real power meter?
No. Peloton does not use a strain gauge power meter like those found on professional outdoor bikes. It estimates power from resistance position and cadence using a precalculated power curve. While the Bike+ adds motorized digital control for better consistency, it still relies on an internal calculation rather than a direct-measurement strain gauge.
Why does the same resistance feel different on two Peloton bikes?
Manufacturing tolerances mean the magnets, sensors, and belt tension differ slightly between bikes. Resistance 50 on your bike could feel like resistance 45 or 55 on another. Calibration reduces this variance but can't eliminate it entirely because each bike's hardware is physically different.
How does cadence affect power on a Peloton?
Higher cadence at the same resistance produces more power. This is because the magnetic braking force increases with flywheel speed — the faster the flywheel spins, the stronger the eddy currents and the more energy is dissipated as braking force. At resistance 50, going from 70 RPM to 90 RPM will significantly increase your output.
Can I trust Peloton output for FTP testing?
Yes, with caveats. Your Peloton FTP is valid for training on your Peloton with consistent calibration. It may not match an FTP test done outdoors or on a different trainer. Always test and train on the same equipment for consistent power zones. If you use FitSwitch with TrainerRoad, take the FTP test through TrainerRoad on the Peloton for best accuracy.
Does standing up change how Peloton calculates power?
No. The power calculation uses resistance position and cadence regardless of whether you're seated or standing. However, standing typically allows you to apply more force at the same resistance level, which naturally increases your cadence (and therefore output) or lets you sustain higher resistance at the same cadence.
Why did my output drop after a software update?
Peloton occasionally adjusts their power curve calculations in software updates. A drop may be an intentional correction. If the drop is severe, it is more likely a calibration issue triggered by the update. Try recalibrating your bike.
Is Peloton output accurate enough for structured training?
For training on your own Peloton, yes. The numbers are consistent enough to set power zones, track progress, and execute interval workouts. The absolute wattage might differ from a lab-grade power meter, but your zones and training stimulus will be valid as long as calibration is maintained. FitSwitch enables ERG mode on the Bike+ for wattage targeting during structured workouts.
What's the difference between kJ and calories on Peloton?
Kilojoules (kJ) measure mechanical work output — the energy you transferred to the flywheel. Calories measure total metabolic energy burned, which includes the roughly 75-80% of energy lost as heat. Because of this efficiency factor, kJ and calories end up being numerically similar, which is a convenient coincidence.
How does Peloton calculate calories?
Peloton calculates calorie burn from your total output (kilojoules) combined with heart rate data if available. Without a heart rate monitor, it estimates calories primarily from power output. With heart rate data, the estimate becomes more personalized because it can factor in your individual cardiovascular response.
Does resistance 100 produce the same power on every Peloton?
No. Due to manufacturing variance and individual calibration differences, resistance 100 on two different Pelotons will produce different maximum wattages. The number is relative to your bike's calibration, not an absolute standard.
Unlock Your Training Potential
Understanding how your Peloton calculates power is the first step to better training. With FitSwitch, you can take that accurate power data and use it in any app you choose, from Zwift to TrainerRoad.
Try FitSwitch — Broadcast your Peloton power, cadence, and heart rate to any app or device.
Disclaimer: The technical details in this article are based on publicly available information about Peloton's resistance system and general principles of magnetic eddy current braking. Peloton's exact power curve algorithm is proprietary. FitSwitch is not affiliated with Peloton Interactive, Inc.
Last updated: February 2026