SHUYO Calculator
Two calculators in one place. Work out what your body is doing, then work out what to feed it. No account, no email required to see your numbers.
Know Your Numbers
Measure in the morning, before eating, in the same conditions each time. The tape measurements are optional but make body fat far more accurate.
Your numbers will appear here.
Your Five Heart Rate Zones
Calculated from your maximum heart rate using the Nes formula (HRmax = 211 − 0.64 × age), which is more accurate for trained adults than the older 220 − age rule.
When to Go to Sleep
Sleep runs in roughly 90-minute cycles. Waking at the end of a cycle feels far better than waking in the middle of one, even after fewer total hours. These times allow about 15 minutes to fall asleep.
Most adults need five to six full cycles. Chase complete cycles rather than a round number of hours.
Your numbers are only the starting point
Send your details and a REPs-licensed coach will read your numbers and come back with what to change first. No cost, no obligation.
Build Your Macro Split
Enter your maintenance calories. If you do not know them, run the Fitness Calculator first and your TDEE will carry across automatically.
Your macro split will appear here.
A split on paper is not a plan
Send your details and a REPs-licensed coach will read your numbers and come back with what to change first. No cost, no obligation.
What Each Measurement Actually Tells You
These calculators return four numbers: body fat percentage, lean body mass, basal metabolic rate and total daily energy expenditure. Each answers a different question, and each is useful only when you understand what it can and cannot tell you.
Body fat percentage describes composition rather than weight. Two people at the same weight and height can carry very different amounts of muscle, which is why the scale alone is a poor guide. The estimate here uses circumference measurements, so treat it as a reliable working figure rather than a laboratory result.
Lean body mass is everything that is not fat: muscle, bone, organs, water. It matters because lean mass is what you are protecting during fat loss. A diet that drops weight while stripping lean mass leaves you lighter, weaker and more likely to regain.
BMR is what your body burns at complete rest, calculated here with the Katch-McArdle formula, which uses lean mass rather than total weight and is therefore more accurate for people who train. TDEE is BMR multiplied by your activity level, and it is the number your daily intake should be set against.
The honest caveat: every one of these is an estimate. Formulas approximate, tape measures vary and activity multipliers are broad. Use them as a starting point, then let the trend over four to six weeks correct the estimate. What your body actually does is better data than any equation.
Once you have your numbers, the SHUYO Score shows which dimension of your practice needs attention first, and SHUYO Fuel turns the targets into meals calculated from your assessment.
How accurate are these calculators?
Circumference-based body fat estimates typically fall within three to four percentage points of a DEXA scan. That is close enough to track direction reliably, which matters more than a single precise figure.
Healthy weight range and ideal weight. The range comes from a BMI of 18.5 to 24.9 applied to your height. It is a population guide, not a target: a lean, muscular person can sit above it and be in excellent health. The Devine figure is a single reference weight used clinically. Treat both as context for your body fat percentage rather than as goals in themselves.
Maximum heart rate and your zones. Max heart rate is estimated with the Nes formula, which is more accurate for trained adults than the old 220 minus age rule. Your zones tell you what a session is actually training. Zones 1 and 2 build the aerobic base most people skip. Zone 3 is where a lot of training accidentally lives, hard enough to tire you, not hard enough to drive adaptation. Zones 4 and 5 develop threshold and top-end capacity, and are the ones you cannot do often.
Sleep is the part of recovery you cannot shortcut. Sleep runs in cycles of roughly 90 minutes, each moving through light sleep, deep sleep and REM. Deep sleep dominates the early cycles and is when most growth hormone is released and physical repair happens. REM dominates the later cycles and is when motor learning and memory consolidate, which is why cutting sleep short costs you the technical gains from training as well as the physical ones.
Waking at the end of a cycle feels dramatically better than waking in the middle of one, even after less total sleep. That is why the calculator gives bedtimes rather than an hours target. Most adults need five to six complete cycles, which is seven and a half to nine hours. Under-sleeping raises perceived effort, blunts strength and appetite regulation, and slows the recovery your training depends on. If you can only fix one thing this month, fix this one.
Should I eat at my BMR or my TDEE?
Neither, as a rule. TDEE is your maintenance estimate. Fat loss generally sits modestly below it and muscle gain modestly above it. Eating at or below BMR for any length of time tends to cost you lean mass.
How often should I remeasure?
Every four weeks, in the morning, before eating, in the same conditions each time. Consistency of method matters more than precision of instrument.