Calories Burned API

Calories & Energy data from every wearable, in one schema

Active and basal energy expenditure, normalised to kilocalories and fusible with nutrition intake.

Start free Which devices supply it

7/8

providers connectable today

webhook event types

Canonical unit

kilocalories

What calories & energy looks like through one API

Energy expenditure is the most model-dependent number any wearable produces. No consumer device measures calories; every one of them estimates from heart rate, movement, and a demographic model using the user's height, weight, age and sex. Two vendors given identical sensor input will return different numbers, and neither is verifiable without a metabolic cart.

WearLink normalises the units and separates active from basal energy — a distinction providers blur constantly, and the most common source of a doubled daily total. series.basal_energy.created carries resting expenditure; series.energy.created carries active. Summing a provider that reports total against one that reports active only produces a number that is wrong in a way nobody notices for weeks.

Because WearLink also ingests nutrition, the burn side pairs directly with the consumed side through the energy-balance endpoint, which is the actual reason most products want calorie data in the first place.

Where providers disagree

Active versus total energy is inconsistently labelled

Some providers report only active calories, some report active plus basal as a single total, and the field naming does not reliably tell you which. WearLink splits them explicitly. If you are migrating from a direct integration, this is the field most likely to change value.

Estimates depend on profile data you may not have

Calorie models need weight, height, age and sex. If a user never completed their device profile, the vendor substitutes defaults and the estimate can be off by a large margin. The error is invisible in the payload.

Cross-vendor comparison is not meaningful

Differences of 20–30% between vendors for the same activity are routine and expected. Use energy for within-user, within-device trends and for balance calculations against intake — not for leaderboards across mixed device populations.

Workout calories and daily active calories overlap

A workout record carries its own energy figure, and the day's active-calorie total already includes that workout. Summing them double-counts, and the error scales with how much the user trains — so it is largest for exactly the users who care most. This is one of the most common bugs in fitness products built on aggregated data. Use the daily total as the authoritative figure and treat workout energy as a breakdown of it, not an addition to it.

Webhook events for calories & energy

Summary: calories.created

Series streams:

series.energy.created
series.basal_energy.created
series.average_met.created
series.physical_effort.created

The full catalogue is in the event catalogue.

FAQ

Calories & Energy — frequently asked questions

Does WearLink separate active and resting calories?

Yes. series.energy.created carries active expenditure and series.basal_energy.created carries basal, so you never have to guess whether a provider total already includes BMR.

Can I compute a daily calorie deficit?

That is what the energy-balance endpoint does — it fuses wearable expenditure with logged nutrition intake into a per-day figure, so you do not have to integrate a separate nutrition service.

How accurate are wearable calorie estimates?

They are model estimates, not measurements, and vendors disagree substantially on identical input. They are useful as consistent within-user signals and unreliable as absolute truth.

Get calories & energy from every device your users own

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