TL;DR: LaChart started as a free lactate calculator and still offers one without sign-up (LaChart calculator). Today it calls itself a “lactate testing app and training platform” for coaches and athletes, with a calendar, structured workouts sent to Garmin, load and form tracking and a coach workspace (LaChart). On the web or in its iPhone app, it compares several threshold methods on one curve, syncs with Strava and exports PDF reports (lactate testing, integrations, LaChart FAQ). Its Coach plan is listed at €14.99 a month for unlimited athletes, with lactate tests that are not metered (LaChart pricing, LaChart: Coachbox alternative). Coachbox is a coaching platform with lactate testing built in and connected to your daily coaching workflow, training planning and reporting, priced by the number of active athletes and per test. Both products now cover a lot of the same ground. In our view, choose LaChart if lactate testing is the center of your work and you want one flat price. Choose Coachbox if you want a wider coaching toolkit around the test: messaging, customizable zone models, direct sync with more device brands and Coachbox AI.
Different Tools, Different Jobs
Earlier versions of this page compared a free calculator with a coaching platform. That no longer describes LaChart. LaChart now sells itself to coaches, athletes and testing studios, with “three workspaces” in one app (LaChart). LaChart’s own comparison page puts it this way: “Coachbox and LaChart aim at nearly the same coach” (LaChart: Coachbox alternative).
LaChart builds everything around the lactate curve. You enter the stages, it calculates LT1 and LT2 with several methods at once and draws the measured points on top, and the zones that follow feed load, session categories and time in zone (lactate testing, zones). You can also tag any lap of any workout with a lactate sample and read it against the athlete’s own curve (LaChart).
Coachbox is a coaching platform where the lactate test is one module among planning, communication, annual periodization, health monitoring and analytics. The lactate module detects LT1 and LT2 automatically in under a minute, and the zones feed straight into the rest of the platform.
So the question is less “calculator or platform” and more “which platform, and how do you want to pay for testing”.
Feature Comparison
Lactate Analysis
| Capability | LaChart | Coachbox |
|---|---|---|
| Lactate curve generation | Yes (lactate testing) | Yes |
| Threshold detection | LT1 and LT2 via log-log, IAT, OBLA 2.0 to 3.5, LTP1/LTP2, D-max and baseline, shown side by side (LaChart: Coachbox alternative) | Automatic LT1/LT2 in under a minute, multiple LT determination methods, drag and drop adjustment of LT1/LT2 |
| Test entry | Type the stages as you run them (lactate testing); a step-test wizard builds the stage ladder (LaChart) | Type the values, or let Coachbox read a photo of a paper protocol |
| Zone models | Five zones, or a Seiler three-zone model (LaChart) | Fully customizable zone model with unlimited custom templates |
| Historical test comparison | Overlay curves across tests (lactate testing) | Yes. Zones are dated, so each workout is analyzed against the zones that applied on that day |
| Lactate samples during training | Tag any lap of any workout with a sample (LaChart) | Not part of our confirmed feature list for this comparison |
| Calculator without an account | Yes (LaChart calculator) | Not part of our confirmed feature list for this comparison |
| Spirometry | We did not find spirometry in LaChart’s feature pages (lactate testing, all features) | Add spirometry data to a lactate test |
Verdict: Both tools detect LT1 and LT2 from a step test and turn them into zones, so threshold analysis is common ground. LaChart shows many methods on the same curve (lactate testing). It also adds lactate samples from any workout (LaChart). Coachbox gives you a zone model you define yourself, keeps older zones on record for older workouts, and lets you add spirometry data.
Platform and Access
| Capability | LaChart | Coachbox |
|---|---|---|
| Web app | Yes (LaChart) | Yes |
| iPhone | Native iOS app, plus an Apple Watch face with your zones (LaChart, integrations) | iOS app |
| Android | “Coming to Google Play” (LaChart) | Android app |
| Workouts in | Strava, Garmin and Apple Health sync, plus .FIT upload from devices such as Wahoo, Polar and Suunto (integrations, LaChart) | Garmin, Polar, Wahoo, Suunto, COROS and Fitbit, plus Apple Health on iPhone |
| Structured workouts out | To the athlete’s Garmin Connect calendar (integrations) | To Garmin, COROS and Wahoo |
Verdict: Both run in the browser and both sync workouts automatically and send planned sessions to the watch. LaChart syncs through Strava, Garmin and Apple Health and takes .FIT files from other devices (integrations). Coachbox connects directly to more watch brands and has an Android app today.
Coaching Integration
| Capability | LaChart | Coachbox |
|---|---|---|
| Training calendar | Planned and completed on one grid (planning) | Yes, with drag and drop planning |
| Workout builder | Steps, ramps, repeats and nested groups, with a template library (planning) | Yes, including a builder that turns a typed description into a structured workout |
| Annual planning | Periodized blocks, target load, races and taper (for coaches) | Integrated annual plan with race calendar |
| Athlete roster | Unlimited athletes on the Coach plan, athlete switcher and status dots (pricing, for coaches) | Athletes included per plan, with a price per extra active athlete |
| Communication | Comments on each session (coaching). We did not find direct or group messaging in LaChart’s feature pages (all features, for coaches) | Comments on workouts, plus direct and group messages |
| Load and form | TSS, CTL, ATL and TSB per athlete (load and form, LaChart: Coachbox alternative) | Training load and PMC |
| Health data | Sleep, HRV, resting heart rate, illness and injury (health) | HRV, sleep and resting heart rate from the device, injuries logged as milestones |
| AI assistant | We did not find an AI assistant in LaChart’s feature pages (all features) | Coachbox AI answers questions about athletes and writes changes into the training plan, plus an MCP connection to ChatGPT, Claude and other assistants |
Verdict: Most of this table is common ground. Both give you a calendar, a workout builder, an annual plan, load and form, health data and comments on sessions. The differences sit at the edges. Coachbox adds messaging outside the workout and Coachbox AI, two things we did not find in LaChart’s feature pages (all features). LaChart keeps one price no matter how many athletes you add (pricing).
Reporting
| Capability | LaChart | Coachbox |
|---|---|---|
| PDF report | Curve, HR overlay, thresholds, zones, stage table, comparison with the previous test and training recommendations (LaChart FAQ) | One-click PDF with automatic calculations |
| Custom branding | Your logo, studio name and address on the Coach plan (pricing, lactate testing) | Lactate test PDF in your own brand, on every plan; the app itself is not brandable |
| Sharing | PDF export (LaChart) | Email the report to the athlete or client |
Verdict: Both produce branded PDF test reports, so this is common ground. With Coachbox, the branding covers the lactate test PDF on every plan; the app itself does not carry your brand.
Advanced Features
| Capability | LaChart | Coachbox |
|---|---|---|
| Sports | Cycling, running, swimming and triathlon (LaChart FAQ) | Multi-sport tests |
| Smart trainer control | Runs structured workouts on a Bluetooth trainer (FTMS) (LaChart) | Not part of our confirmed feature list for this comparison |
| Population comparison | Benchmark LT1/LT2 against athletes on LaChart (LaChart) | Not part of our confirmed feature list for this comparison |
| Threshold shift nudge | Flags when sessions suggest a threshold moved (zones) | Not part of our confirmed feature list for this comparison |
| User base | LaChart calls itself “younger and smaller” than Coachbox (LaChart: Coachbox alternative) | 25,000+ users, 12M+ workouts, 35+ countries |
Verdict: LaChart has several testing-focused extras, such as population comparison, trainer control and a nudge when a threshold moves (LaChart). Coachbox brings spirometry data in the test and a larger user base (LaChart: Coachbox alternative).
Sustainability and Support
| Capability | LaChart | Coachbox |
|---|---|---|
| Company | LaChart describes itself as “younger and smaller” (LaChart: Coachbox alternative) | Coaching platform with 25,000+ users |
| Revenue model | Free plan plus paid Athlete and Coach plans (pricing) | Paid coach plans and the One plan for self-coached athletes; athletes of a coach use the app for free |
| Data export | Training history as CSV and tests as PDF (LaChart FAQ) | Test reports as PDF |
Verdict: Both run on subscriptions. How much weight you give company size is your call; LaChart itself names it as a reason some coaches stay with Coachbox (LaChart: Coachbox alternative).
The Workflow Difference
Both tools now carry a test through to the training week. Here is what a testing day looks like in each, based on how each product describes it.
A Lactate Test with LaChart
- Run the test and collect lactate samples at each stage
- Enter the stages in LaChart, on the web or in the iPhone app (lactate testing)
- Compare LT1 and LT2 across the methods on the curve
- Zones update from the new test (LaChart)
- Export a branded PDF for the athlete on the Coach plan (pricing)
- Build the week and send it to the athlete’s Garmin (for coaches)
- Discuss the sessions in the comments under each training (coaching)
A Lactate Test with Coachbox
- Run the test and collect lactate samples at each stage
- Type the values, or take a photo of the paper protocol
- Coachbox detects LT1 and LT2 automatically in under a minute; adjust them by dragging if needed
- Zones update in the athlete’s profile, dated, so older workouts keep their old zones
- Send the branded PDF report to the athlete
- Plan the next block in the calendar and annual plan; planned workouts go to Garmin, COROS or Wahoo
- Discuss the results in a message or in the comments on the workout
The steps look alike. The practical differences are how zones are modeled, which watches the athlete uses, and whether you want messaging and Coachbox AI next to the test.
Pricing Comparison
The two products price in different ways. LaChart charges one monthly price per coach with unlimited athletes and no per-test fee (LaChart: Coachbox alternative). Coachbox charges by plan, with a set number of active athletes included, a fee per extra active athlete and a price per lactate test.
| LaChart | Coachbox | |
|---|---|---|
| Free option | Free plan with 3 lactate tests and Garmin and Strava sync; Athlete and Coach plans start with 2 weeks free; the calculator works without an account (pricing) | 14-day free trial, no credit card |
| Coach plan | Coach: €14.99/month as listed, unlimited athletes (pricing) | Base 19 EUR/month billed yearly or 25 EUR billed monthly, excl. VAT, 5 athletes included. Build 49/65, Peak 79/99, Prime 149/190 EUR excl. VAT, with 25/50/100 athletes included |
| Extra athletes | Included, “no per-athlete surcharge” (LaChart: Coachbox alternative) | 2.50/2/1.75/1.50 EUR excl. VAT per extra active athlete, depending on the plan. Only athletes with workouts planned in the future count |
| Lactate tests | Unlimited on paid plans, not metered (pricing, LaChart: Coachbox alternative) | 6/5/4/3 EUR excl. VAT per test depending on the plan, with 5/10/15/20 free tests at the start of the licence |
| Testing only | €14.99/month as listed, with unlimited people tested, tests and reports (for testers) | Standalone Lactate Module: 49 EUR/month billed yearly, excl. VAT, with packs of 50/100/250 tests for 250/400/750 EUR excl. VAT |
| Self-coached athlete | Athlete: €6.99/month as listed (pricing) | One: 4 EUR/month billed yearly, excl. VAT |
| Athletes of a coach | Free plan includes “Connect with your coach” (pricing) | Free |
Coachbox lists its prices without VAT. LaChart lists €6.99 and €14.99 per month and does not state on its pricing page whether VAT is included or which billing period applies beyond “/ month” (pricing), so we show LaChart’s amounts exactly as listed and do not convert them. For the same reason we cannot put both athlete prices on the same VAT basis; Coachbox’s One plan costs more than 4 EUR once your country’s VAT is added.
Which one costs less depends on how you work. LaChart’s flat price does not change with roster size or the number of tests (LaChart: Coachbox alternative). With Coachbox, the total depends on the plan, the number of active athletes and how many tests you run after the free ones. If you run many tests on a large roster and need nothing beyond what LaChart offers, LaChart’s model is simpler to budget. If you want the features that are specific to Coachbox, weigh them against the per-test and per-athlete fees.
Sources: LaChart pricing, LaChart for testers, Coachbox pricing. For a complete breakdown, see the LaChart Pricing analysis.
Who Should Choose LaChart
LaChart is the better fit if you:
- Run many lactate tests and want no per-test fee on a paid plan (pricing)
- Coach a large roster and want one price no matter how many athletes you add (LaChart: Coachbox alternative)
- Want to compare threshold methods on one curve, with the measured points drawn on top (lactate testing)
- Take lactate samples during training, not only in formal step tests (LaChart)
- Need a quick analysis without an account, through the free calculator (LaChart calculator)
- Work mainly with Garmin, Strava and Apple Health users (integrations)
- Are an individual athlete who wants to track your own tests, with three free tests to start (pricing)
Ideal LaChart user: A coach or testing studio whose work centers on the lactate curve, who tests often, and who wants one flat monthly price for the whole roster.
Who Should Choose Coachbox
Coachbox is the right choice if you:
- Want to define your own zone models, with unlimited custom templates
- Want older workouts analyzed against the zones that applied at the time, so a new test doesn’t rewrite history
- Combine lactate testing with spirometry data in the same test
- Message athletes and your team in direct and group messages, next to comments on workouts
- Coach athletes on Polar, Suunto, COROS, Wahoo or Fitbit and want their workouts to arrive directly
- Want an AI assistant that knows your athletes’ data and can change the training plan, or want to connect ChatGPT or Claude over MCP
- Have athletes on Android who want a native app today
Ideal Coachbox user: An endurance coach who runs lactate tests as part of daily coaching and wants testing, planning, communication and analytics in one platform, with room to shape zones and reports to their own method.
Can You Start with LaChart and Move to Coachbox Later?
Yes. What changes is where you enter the results. Both products take lactate values you type in, and Coachbox can also read a photo of a paper protocol.
Training history moves through the athletes’ devices. When an athlete connects Garmin or Wahoo to Coachbox, they pick a start date and the history imports in the background. LaChart describes the same route in the other direction: there is no direct importer between the two, and history arrives through Strava, Garmin Connect or .FIT upload (LaChart: Coachbox alternative).
A Note on Fair Comparison
In our view, LaChart has grown fast. A product we first compared as a free calculator now covers much of what a coaching platform does, and it keeps the free calculator open to anyone (LaChart calculator). LaChart’s own page about Coachbox is fair to us too, including a section on where Coachbox is the better choice (LaChart: Coachbox alternative). We try to return the favor here.
The comparison is useful not because one tool is “better”, but because coaches test and coach in different ways. Knowing where each tool puts its weight helps you choose for where you are now.
The Bottom Line
LaChart and Coachbox now aim at much of the same coach (LaChart: Coachbox alternative).
LaChart builds everything around the lactate curve, with a flat monthly price, unlimited athletes and unmetered tests on its paid plans. In our view it is a strong pick for coaches and studios who test often and want simple pricing.
Coachbox is a coaching platform with lactate testing built in, priced by active athlete and per test. In our view, its strengths for a testing coach are customizable zone models, dated zones, spirometry data, direct and group messaging, direct sync with more device brands and Coachbox AI.
The right choice depends on one question: do you want the lactate curve at the center with one flat price, or a wider coaching toolkit around the test?
If it’s the curve and the flat price, try LaChart. If it’s the wider toolkit, try Coachbox with a 14-day free trial. Both offer a free way to start (LaChart pricing), so you can put your own test data through each before you decide.