How CamPlay estimates calories
The exact formula behind the flame icon — and what it can’t tell you.
Several CamPlay games show a live calorie counter while you play. This page documents exactly how that number is computed — the formula, the inputs, and the limitations — because a fitness number you can’t interrogate isn’t worth much. The short version: it is a physics-grounded estimate of your energy expenditure, not a medical measurement.
The formula
CamPlay uses the MET system (Metabolic Equivalent of Task), the same framework exercise science uses to compare activities. One MET is roughly the energy you burn at rest; an activity rated 4 METs burns about four times that. The convenient property of METs: 1 MET ≈ 1 kilocalorie per kilogram of body weight per hour. So the counter integrates, every frame:
kcal per second = MET × body weight (kg) ÷ 3600
The MET value isn’t fixed — it changes moment to moment based on what the pose tracker sees your body doing. CamPlay assigns each movement a MET value adapted from the Compendium of Physical Activities, the reference catalogue used in exercise research:
| What the camera sees | MET value | Basis |
|---|---|---|
| Standing in frame, between actions | 1.8 | Light standing activity |
| Jogging in place | 2.0 + speed × 6.5 | Scales live with your pace: a light jog lands around 4, a flat-out sprint around 8.5 |
| Holding a duck / squat / speed tuck | 4.0 | Isometric squat hold |
| Holding a lean (carving, dodging) | 2.5 | Side-bend effort |
| Each jump | +0.005 kcal per kg | One-off burst bonus added per hop, on top of the current rate |
When several things happen at once, the counter takes the highest applicable rate rather than stacking them — ducking while jogging counts as whichever is more intense, not the sum. That’s a deliberately conservative choice: we’d rather slightly undercount than flatter you.
What goes in
Your body weight. Energy cost scales with body mass, so weight is the one personal input that matters most. You can set it on any game page or in your profile; it’s accepted between 20 and 250 kg. If you never set one, the counter assumes 70 kg — so until you enter your real weight, the number is generic. Your weight is stored in your browser (and in your profile if you sign in) and is never shown to other players.
Your live movement. The pose engine’s signals — running speed from arm-pump cadence and head bob, held ducks and tucks, leans, jumps — select the MET value from the table above, frame by frame. Speed is continuous, so jogging harder genuinely raises the burn rate in real time rather than in steps.
Honesty rule: no camera, no calories. The counter only runs while pose tracking is live and actually sees you. Play with keyboard controls, or step out of frame, and the count pauses. You can’t farm calories by holding an arrow key.
A worked example
A 70 kg player jogs through a Rune Run session at a moderate pace (around MET 6) for five minutes: 6 × 70 ÷ 3600 ≈ 0.117 kcal per second, or about 35 kcal — plus a small bonus for every jump (0.005 × 70 = 0.35 kcal per hop). That’s comparable to what a fitness tracker would credit for a brisk five-minute jog, which is the point: the movement is real, so the estimate can be grounded in the same physiology.
Where the number shows up
All five games estimate calories with this same formula. Rune Run, Red Light, Green Light and Ski Slalom display a live flame counter while you play; Simon Says and Dino Dodge count in the background and credit the total when your run is saved. Estimates accumulate into daily and lifetime totals on your stats page, and calories appear on leaderboards and shared runs alongside your score.
What the estimate cannot tell you
Be clear-eyed about the limits. MET values are population averages measured in laboratories — your personal burn depends on age, sex, fitness level, body composition and technique, none of which the camera knows. The tracker sees movement, not physiological effort: it can’t read your heart rate, and a camera-based system can be fooled in ways a chest strap can’t. Two people of the same weight doing the same session will not burn identical energy in reality, even though CamPlay will credit them identically.
Treat the number as a consistent, comparable estimate: excellent for comparing your own sessions, seeing that today you worked harder than yesterday, or keeping a streak honest — and not as a medical-grade measurement. CamPlay is not a medical device, and calorie estimates are not medical or dietary advice. If you need precise energy-expenditure numbers for a health condition, use clinical tools and talk to a professional.
Why we built it this way
We could have shown a bigger, more flattering number — plenty of fitness products do. We’d rather the counter be defensible: a documented formula, standard reference values, conservative rules, and a zero when the camera can’t see you. If you spot something that feels off, tell us on the feedback page — the methodology is actively maintained. For more on how the movement detection itself works, see About CamPlay.