Best Free VBT Apps: Track Bar Speed Without Buying a $1,000 Device
Velocity-based training (VBT) is simple in principle: measure how fast the bar moves, and use that number to set loads, judge fatigue, and estimate 1RM. The usual obstacle is the price of the measuring tool. A linear position transducer such as GymAware or Tendo costs 2,000, and the validated mid-range options still run $450 or more.
Free VBT apps remove that obstacle. They use the camera already in your pocket instead of a tethered encoder. The accuracy gap with hardware is real but narrower than the price gap, and for most lifters a phone app is accurate enough to make VBT useful. This guide compares the free options that actually work, what independent validation exists for them, and how to set up your first velocity session.
What a free VBT app actually measures
VBT apps fall into two families, and the difference matters more than the brand:
- Camera-based apps (computer vision). You prop the phone sideways on the floor, point it at the bar, and record the set. The app tracks the barbell in the video and derives mean concentric velocity, range of motion, and often bar path. Nothing is attached to the bar.
- Sensor-based apps (IMU). The app reads the accelerometer and gyroscope inside your phone or Apple Watch. The device usually needs to be attached to the bar or held by the athlete, which makes this approach more common on Apple Watch than on a standalone phone.
Camera apps are the mainstream free option because the setup is a phone and a place to stand it. Some apps process video on the device, some upload it, so check the privacy terms if that matters to you.
The free VBT apps worth comparing
These are the apps most often recommended when the question is "free VBT without hardware". Prices are what the stores list as of August 2026; check before you rely on a number.
| App | How it measures | Free tier | Platforms | Independent validation |
|---|---|---|---|---|
| Metric | Camera (computer vision) | Free, unlimited sets | iPhone, Android | Taber et al. 2023 reported ICC 0.79 to 0.94 for mean velocity vs 3D motion capture |
| Qwik VBT | Camera (computer vision) | Free, one-off $28 upgrade | iPhone, Android | Renner, Mitter & Baca 2024 found it the most valid of the three apps tested, against RepOne and Vicon |
| Power VBT | Camera (video analysis) | Free to start | iPhone, Android | No published study found |
| WL Analysis | Camera (video analysis) | Limited free version, $8.99 one-off | iPhone, Android | None found at time of writing |
| Spleeft | Phone or watch IMU | 3-day trial, then ~$23+/year | iPhone, Android, Apple Watch | None published; the validation pages on the site are written by the founder |
Two warnings apply to all of them. First, "validated" is not a fixed label. The studies above test a specific app version on specific lifts, and apps change faster than papers. Second, a paid app is not automatically more accurate than a free one. Price predicts features, not precision.
What Power VBT does differently
Power is the app built alongside this site, so its description here stays with what a user can verify in a session.
Setup starts with less friction than most camera apps. You do not select the exercise or mark the plates by hand: Power detects the movement and calibrates from the plate automatically, then reports mean concentric velocity and bar path for every rep. The analysis runs on your device, and training videos are never uploaded.
Accuracy is stated the same way. Under recommended recording conditions, mean concentric velocity is accurate to about 5 percent, on the same order as mid-range commercial VBT devices. Power labels peak velocity and range of motion as lower-confidence metrics instead of presenting every number as equally reliable, and its velocity-based 1RM estimate comes from your own load-velocity data rather than a generic population formula.
What the evidence says about phone-based VBT
The two studies most often cited are worth reading yourself, because the summaries travel faster than the caveats.
Taber et al. 2023 (International Journal of Strength and Conditioning). This study tested a video-based app (an early Metric version) against 3D motion capture on bench press, back squat, and deadlift across more than 800 reps. Mean velocity showed good to excellent reliability, with ICC ranging from 0.79 to 0.94, and the authors concluded the app was valid and reliable for tracking displacement and velocity. It validates one algorithm version against a gold standard, not the whole category.
Renner, Mitter & Baca 2024 (PLOS One). This is the more useful study for comparison shopping because it is a head-to-head: Qwik VBT, Metric, and MyLift were recorded simultaneously with a RepOne encoder and a Vicon motion capture system on squat, bench, and deadlift across 589 reps. The results are not uniform. Qwik delivered the best results overall, with root mean square error of 0.01 to 0.04 m/s compared with Vicon, close to the hardware RepOne. Metric matched RepOne on bench press but fell short on squat and deadlift in this test, and MyLift did not reach hardware-level validity on any lift. The conclusion is that phone apps can be as valid as a transducer, but the specific app matters more than the category label.
The broader literature is less flattering to the category. A systematic review of load-velocity 1RM prediction found useful monitoring potential alongside meaningful prediction uncertainty (PubMed). In plain terms: use a free app to monitor fatigue and readiness, and treat its 1RM estimate as a range rather than as a substitute for a real max attempt.
How to estimate 1RM from bar speed
A free VBT app gives you velocity at a known load. To turn that into an estimated 1RM you need the load-velocity relationship for the lift, which is roughly linear between about 60% and 90% of 1RM, and a minimum velocity threshold (MVT) for the exercise. Typical MVT starting points are around 0.30 m/s for back squat, 0.20 to 0.25 m/s for bench press, and 0.15 m/s for deadlift, but the individual number varies.
The procedure is the same across apps:
- Warm up, then do 3 to 6 working sets spread across roughly 60% to 90% of your estimated 1RM.
- Record the load and the mean concentric velocity of the fastest rep in each set.
- Fit a line through those points and find the load where it crosses the MVT. That load is your estimated 1RM.
Apps that build a load-velocity profile do this fitting for you. Power VBT reports mean concentric velocity and bar path for every rep and can build the profile from recorded or imported video. If you do not want another app, you can enter the same loads and velocities into any spreadsheet and fit the line yourself.
Cross-check the result against a rep-based estimate. Enter a recent set in the MaxRep 1RM calculator and compare the two numbers. When they disagree by more than a few percent, treat the spread as information about your fatigue and technique that day, not as one of the two being wrong.
The honest limits of free VBT
Free phone apps are not a free lunch. They need good lighting and a stable camera position, they struggle with non-standard plates or wide camera angles, and their accuracy at very slow speeds near a true max is the weakest part of the curve. If you are doing precision work on a 1RM attempt, an encoder is still the better tool.
What a free app is excellent for is the daily work: setting velocity targets, watching velocity loss across sets, and comparing today's bar speed with last week's. That is where VBT earns its keep, and it costs nothing beyond the phone you already own.
Where to start
Pick one app, not three. The best first session is a bench press day with a stable floor phone stand:
- Set the phone sideways on the floor, three to five feet from the bar.
- Record a warm-up set and check that the app tracks the bar cleanly.
- Run your normal session. Log load and the fastest rep velocity for each set.
- After the session, compare your bar speed at the same load with last week's number if you have one.
Start with Qwik VBT if you want the strongest head-to-head evidence against hardware. Start with Metric if you want the widely cited bench press validation. Start with Power VBT if you want bar path and a load-velocity profile in the same free app. Whichever you choose, use the MaxRep 1RM calculator alongside it for a formula-based second opinion.