Open calculators
The formula is part of the answer.
These calculators run entirely in your browser. Each result shows the method, the assumption, and the point where the number stops deserving confidence.
Free tool
One-rep max calculator
Estimate 1RM from a working set using the Epley formula and see a rep-range confidence note.
- Input
- Weight + reps
- Output
- Estimated 1RM
Free tool
Weekly training volume calculator
Total direct and secondary hard sets for one muscle across several exercises and sessions.
- Input
- Sets + frequency + contribution
- Output
- Weekly hard sets
Free tool
Macro calculator
Calories, protein, carbs, and fat from Mifflin-St Jeor, activity multipliers, and goal-based protein — every step documented.
- Input
- Stats + activity + goal
- Output
- Daily calorie & macro targets
Want the reasoning before the result? Browse thescience library or start with theworkout journal guide.
Coming to iOS
Calculators underneath. Notebook on top.
Flexbound is coming to iOS, TestFlight first. One email when it opens. Nothing else.