Intervals.icu Pricing 2026: Is It Really Free? (Supporter Tier Explained)

TL;DR: Yes, Intervals.icu is really free. Its pricing page lists a free plan at $0 “forever” with no credit card, and says the core platform has no trials or time limits (Intervals.icu pricing). Fitness, fatigue and form tracking, activity analysis with automatic interval detection, the power curve, the training calendar, the workout builder and device sync through its integrations are all in that free tier. The optional Supporter tier costs $4 per month and adds extras such as an annual training plan builder, full Strava history import, completely custom zones, weather analysis, and teams and coaching organisations (pricing). In our view, free covers what most self-coached athletes need. For coaches, the subscription is the small part of the cost. The bigger part is what you run in other tools: billing, client reports and lactate test analysis, which we did not find in Intervals.icu’s feature pages.

Intervals.icu Pricing Overview

Intervals.icu keeps pricing simple: the platform is free, and people who want to fund its development pay $4 per month for the Supporter tier. You can cancel Supporter at any time (pricing). The pricing page shows no athlete counts, per-seat fees or separate coach editions, and no trial, because the core platform is free to begin with (pricing).

Intervals.icu started in mid-2018 as a side project by David Tinker, a software developer and cyclist in Cape Town. He went full-time on it in September 2024, and a small team now builds it with him, supported by volunteers from the community (About Intervals.icu). The service is operated by Intervals.icu Ltd, with an address in London (privacy policy, Intervals.icu). The site says it has 160,000+ active athletes and 193M+ analyzed activities, and that Supporters “help fund development and keep the platform independent” (Intervals.icu).

The Free Tier

Intervals.icu lists these in the free plan (pricing):

• Fitness, fatigue and form tracking: The Performance Management Chart with CTL, ATL and TSB, configurable time constants and custom charts (fitness chart). For comparison, TrainingPeaks shows the Performance Management Chart to the coach only on a Basic athlete account, and to coach and athlete on Premium (TrainingPeaks coach pricing)
• Activity analysis: Automatic interval detection, power charts, decoupling and zone time distribution (Intervals.icu)
• Power curve and HR analytics: Season comparison, watts per kilogram, eFTP and power models such as Morton’s 3P and Monod & Scherrer (Intervals.icu)
• Training calendar and workout builder: Drag-and-drop planning, structured workouts with power, heart rate, pace or cadence targets, and ZWO, FIT, MRC and ERG import and export (Intervals.icu)
• Device and platform integrations: The site shows Garmin, Polar, Suunto, Coros, Wahoo, Strava, Zwift, MyWhoosh, Rouvy, Oura, WHOOP, Concept2 and more (Intervals.icu, pricing FAQ)
• Multisport support: Separate zones and settings per sport (Intervals.icu)
• Custom charts (pricing)

The free plan needs no credit card and has no expiry (pricing). Coaching also starts free: “Anyone can coach on Intervals.icu”, and any user can follow (read only) or coach (write access) another athlete who accepts the request (coaches, athlete management).

The Supporter Tier: 4 Dollars per Month

The pricing page lists these Supporter features (pricing):

• Advanced weather analysis
• Annual training plan builder
• Import of full Strava history
• Route matching and automatic commute flagging
• Customizable activity summary
• Completely custom zones
• CSV upload of activity stream data
• Teams and coaching organisations
• Bulk athlete configuration
• Early access to beta features
• Supporter feature requests move up the to-do list

Two of these matter specifically for coaches: teams and coaching organisations, and bulk athlete configuration. In our view, a coach who runs a group of athletes on Intervals.icu will want the Supporter tier for those two. The page lists the price as $4 per month and does not say whether that includes VAT or sales tax (pricing). In our view, that makes it one of the lowest-priced subscriptions a coach can use in endurance software.

What “Free” Buys You

In our view, this model is unusual: much of Intervals.icu’s analytical core overlaps with what TrainingPeaks puts in Premium, which TrainingPeaks lists at $19.95 per month billed monthly or $134.99 per year for athletes, before tax, which it adds on the invoice (TrainingPeaks athlete pricing, sales tax). TrainingPeaks lists its Coach Edition from $21.99 per month billed monthly with 4 Basic athletes and 1 Premium athlete included, or $54.99 per month for 5 or more Basic athletes, plus a $99 start-up fee that the page waives with a coupon code, with “additional taxes may apply” (TrainingPeaks coach pricing). Intervals.icu’s own homepage quotes a user who writes: “I canceled my TP Premium and support them now” (Intervals.icu).

We saw no ads on the site. Its privacy policy says your activity and wellness data is private by default and is not shared with third-party applications you did not authorize (privacy policy).

The caveat is structural rather than hidden. Intervals.icu is a small team funded by Supporters (About, pricing). It has run since 2018 (Intervals.icu). Its privacy policy gives support@intervals.icu as a contact address (privacy policy), but we did not find a service level agreement or published response times on its website; much of the day-to-day help runs through the community forum (About, forum). In our view that matters more the more professional your use of it becomes.

The Real Costs for Coaches

In our view, for a professional coach the subscription price is the smallest part of the calculation. The other costs of a coaching practice on Intervals.icu come from what you run in other tools.

Billing and Client Administration

We did not find athlete billing, subscription automation or invoicing in Intervals.icu’s feature pages or pricing (pricing, athlete management). If you coach on it, you charge clients through separate tools (Stripe, bank transfers, accounting software). Coachbox does not automate this yet either: athlete billing and subscriptions are coming soon, not live.

Lactate Test Analysis

Intervals.icu can hold lactate data. It shows a lactate chart on the activity timeline for data from Q-LAC continuous lactate devices (forum announcement), users log blood lactate values with custom interval fields (forum), and you can base zones on your lactate threshold heart rate (forum). Its eFTP estimate from maximal efforts keeps power zones current without a test (fitness chart). We did not find automatic LT1 and LT2 detection from a lactate step test in its feature pages. If you run step tests, you analyze them elsewhere and enter the thresholds yourself.

Client-Ready Output

We did not find branded PDF reports for athletes among Intervals.icu’s features (Intervals.icu, pricing). Coaches who charge for testing or season reviews build those documents in another tool.

Support Is the Community

Intervals.icu’s About page describes a community of volunteer moderators and contributors who answer questions on its forum (About, forum). Its privacy policy lists support@intervals.icu as a contact address (privacy policy). We did not find a ticket desk or published response times on its website. In our view that is a different proposition when a sync problem hits during a paying client’s race week.

The Learning Curve, Multiplied by Your Roster

In our view the platform is dense: it offers custom charts from more than 70 metrics, custom JavaScript and custom fields (custom charts, Intervals.icu). We did not find an official native mobile app on its website, and forum answers say there is none (forum); community developers build mobile apps on its API, such as Subintervals for iOS and Android (forum). In September 2026 the developer wrote that a native iOS and Android app is in progress, and that you can already install the web app on your phone for push notifications (forum). A data-savvy athlete enjoys that depth. In our view, a roster of 20 athletes with mixed technical appetite will not all get comfortable, and the coach absorbs the questions.

Is Intervals.icu Good Value?

For self-coached athletes: in our view, few options come close. The free plan covers what most athletes need, and Supporter adds the rest for $4 per month (pricing). If that describes you, sign up and consider supporting the project.

For coaches, the answer depends on what your practice needs. If your coaching is analysis guidance for self-sufficient athletes, Intervals.icu plus the Supporter tier is, in our view, a complete and nearly free toolkit. If your practice includes client billing, branded reports, lactate test analysis, or athletes who need a guided app, Intervals.icu covers one part of your stack and leaves the rest to other tools. The full picture is in our Intervals.icu Review.

How Coachbox Pricing Compares

Coachbox sits at the other end of the same spectrum: a paid platform built for the coaching practice, with lactate testing included. All Coachbox prices below exclude VAT (Coachbox pricing).

Coachbox Coach Plans

The extra-athlete fee counts active athletes only, meaning athletes with workouts planned in the future. The free tests come with the start of your license, not every month. Every plan includes the full feature suite: training planning, athlete communication, calendars, analytics, device sync with Garmin, Polar, Suunto, Coros, Wahoo, Fitbit, Apple Watch and TomTom, lactate testing with training zones, and Coachbox AI, which answers questions about your athletes and writes changes straight into the training plan. There is a 14-day free trial with no credit card, and athletes who train with a coach use the app for free.

Where Coachbox Goes Further

Common Ground

Both products give you a training calendar with structured workouts, sync with the major watch brands, and a way for coach and athlete to talk. Intervals.icu has chat with workout sharing and group messaging, athlete management with tags, and an Ask A Coach feature (Intervals.icu, athlete management, Ask A Coach). On both, the athlete pays nothing to be coached.

Where Intervals.icu Has the Advantage

• Price: Free, or $4 per month for Supporter (pricing), against Coachbox plans from 19 EUR per month billed yearly, excl. VAT.
• Analytical customization: Custom JavaScript for computed fields, custom streams and Plotly charts, plus custom charts from more than 70 metrics (Intervals.icu, custom charts).
• Open API ecosystem: Every user gets a personal API key, and the site says 250+ third-party apps integrate through it (open API, app integrations).
• Interface languages: 21, with community translations (Intervals.icu, About).

In our view, on price and analytical freedom Intervals.icu wins outright. On the coaching workflow around lactate test analysis, client reports and education, Coachbox covers ground we did not find in Intervals.icu’s documentation.

Side-by-Side Pricing Comparison

VAT note: Intervals.icu lists $4 per month and does not say whether VAT or sales tax is included (pricing), so we show its price as listed and do not convert it. Coachbox coach prices exclude VAT. The Coachbox athlete price incl. VAT uses the 19% German VAT rate. The two products bill differently (a flat Supporter fee against a plan with athletes included and a fee per extra active athlete), so we do not add them up into one yearly total per roster.

When Intervals.icu’s Pricing Makes Sense

You coach yourself. In our view there is no better deal. Take the free plan, and if the platform earns a place in your daily training, Supporter is a fair way to fund it.

You coach a few self-sufficient athletes. Coaching access is free, and Supporter adds teams and bulk athlete configuration for $4 per month (pricing). That works if your athletes like a data-dense interface and you handle billing and reports elsewhere.

You want analysis alongside another platform. Intervals.icu imports history from Strava, Garmin, TrainingPeaks and more (fitness chart), so you can run it next to your main platform for its charts. At zero cost, it earns that spot easily.

When Coachbox’s Pricing Makes More Sense

You test your athletes. Lactate testing is part of every Coachbox plan, with free tests at the start of your license and automatic LT1/LT2 detection. Next to Intervals.icu you analyze step tests in separate software and enter the thresholds by hand, and in our view that time adds up faster than the subscription difference.

Your athletes are clients, not power users. Coachbox gives athletes a web, iOS and Android app with their plan and a direct line back to you. You do not ask paying clients to learn a data workbench.

You charge for professional deliverables. Branded PDF test reports are part of what a client pays for. A plan that produces them in one click is, in our view, a business expense that pays for itself.

You want a support team behind your workflow. Coachbox has a help center, a contact form and support@coachbox.app. In our view that matters when the platform is how you earn your living. See the full comparison in Coachbox vs Intervals.icu.

Who Should Use Intervals.icu

Use Intervals.icu if you are self-coached, if you want deep analysis at no cost, or if you coach a small group of athletes who enjoy data. It also fits if you want to customize your analysis with your own fields, charts and JavaScript, or build on an open API with a personal key (open API). Coaches who already run testing and billing in other tools can add Intervals.icu for analysis without adding much cost.

Look elsewhere if your practice depends on lactate test analysis, branded client reports or a support desk with published response times, or if your athletes want an official native mobile app today; the developer says one is in progress (forum).

Making Your Decision

Choose Intervals.icu if you are self-coached or coach a small group of data-comfortable athletes, and your practice does not depend on testing, billing or client reports. In our view it is excellent at analysis, and its community forum is active and helpful.

Choose Coachbox if coaching is your profession and you want testing, communication, client reports and support in one subscription. Plans start at 19 EUR per month billed yearly, excl. VAT, with a 14-day trial and no credit card. The cheapest way to decide is to run it alongside Intervals.icu for two weeks and see which one carries more of your actual work.

And if you are comparing the free option against the industry standard instead, read Intervals.icu vs TrainingPeaks or our TrainingPeaks Pricing breakdown.