Interactive Tools & Calculators

Welcome to the interactive hub of Trebellos. Here you will find accurate calculators, based on validated mathematical and scientific models, designed to help you plan your nutrition, track your athletic progress, and project your financial freedom.

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Trebellos Tools Suite: Interactive scientific and mathematical calculators grouped into three categories: Health & Nutrition, Sports & Performance, and Personal Finance.
🥗 Category: Health & Nutrition

Total Daily Energy Expenditure (TDEE) & Macro Calculator

Calculate your basal metabolic rate using the validated Mifflin-St Jeor formula, your maintenance calories based on daily activity, and optimal macronutrient split for your physical goals.

YOUR ESTIMATED RESULTS
-- kcal / day
Daily target calories
Basal Metabolic Rate (BMR) -- kcal
Maintenance (TDEE) -- kcal

Daily Macronutrient Distribution

Proteins -- g
-- kcal
Healthy Fats -- g
-- kcal
Carbohydrates -- g
-- kcal
💧
Recommended daily water intake: 3.2 liters/day (adjusted for body weight and exercise).
🥗 Category: Health & Nutrition

FFMI Calculator (Fat-Free Mass Index)

FFMI measures your lean muscle mass relative to height, discounting body fat. It is the gold standard metric for assessing true muscular development and estimating your proximity to the natural limit.

💡 Don't know your body fat %? Estimate it with a bioimpedance scale, calipers, or visual comparison guides. An approximation gives a reliable FFMI.
YOUR MUSCLE MASS INDEX
-- FFMI
Enter your data to calculate
Normalized FFMI (to 1.80m / 5'11") --
Lean mass (fat-free) -- kg
Lean mass (--%) Fat mass (--%)

FFMI Interpretation Scale

Range (Norm. FFMI) Interpretation

The natural genetic ceiling typically sits around 25 for men and 22 for women (normalized FFMI). Significantly higher values are exceedingly rare without pharmaceutical assistance.

🥗 Category: Health & Nutrition

Optimal Daily Protein Intake Calculator (Scientific Evidence)

Calculate your daily protein requirements based on gold-standard meta-analyses (Morton et al. 2018, Helms et al. 2014) according to body weight, body fat %, and training goals. Includes meal distribution and real food equivalents.

💡 Protein synthesis rule: To maximize mTORC1 activation, studies indicate each meal should provide between 0.4 and 0.55 g/kg of high biological value protein (hitting ~2.7 - 3g leucine threshold).
YOUR OPTIMAL PROTEIN INTAKE
135 - 165 kcal / day
Relative ratio: 1.8 - 2.2 g per kg body weight
Per meal (4 servings) 35 - 42 g
Protein calories 540 - 660 kcal

Daily Real-Food Equivalents (Reference Sources)

Chicken breast (cooked) ~484 g
Whole eggs (M/L) ~23 units
Firm tofu (drained) ~882 g
Whey protein powder ~6.3 scoops (24g each)

Scientific Methodology and Calculation Criteria

This tool avoids outdated 0.8 g/kg RDA guidelines (originally designed merely to prevent clinical deficiency in sedentary populations). Instead, it incorporates findings from the largest meta-analysis to date (Morton et al., 2018; British Journal of Sports Medicine) showing muscle building benefits plateau between 1.6 and 2.2 g/kg/day. For hypocaloric cutting phases, it integrates Helms et al. (2014) recommending 2.0 - 2.4 g/kg to prevent muscle loss.

⚠️ Important Medical Limitations:

These target figures apply to healthy adults with normal kidney and liver function. High protein intakes up to 2-3 g/kg show zero renal harm in healthy subjects (Antonio et al., 2016). However, individuals diagnosed with Chronic Kidney Disease (CKD) must consult their nephrologist for individualized clinical guidelines.

Frequently Asked Questions on Daily Protein

Is there an absorption ceiling for protein per single meal?

The human intestine absorbs nearly 100% of ingested amino acids. What reaches a per-meal ceiling is the muscle protein synthesis (MPS) trigger, which saturates around 30-45 grams. Splitting daily protein across 3 to 5 meals optimizes daily MPS spikes.

Is the 30-minute post-workout anabolic window mandatory?

No. The anabolic opportunity window spans roughly 4 to 6 hours around training. Prioritize hitting daily protein targets and having a protein-rich meal within 2 to 3 hours before or after training.

Is plant-based protein equivalent to animal protein?

Plant sources feature slightly lower leucine concentrations. By combining legumes with grains or increasing total daily intake by ~10% (1.8-2.2 g/kg), hypertrophic gains match an omnivorous diet.

🏃 Category: Sports & Performance

Running Pace & Race Time Predictor Calculator

Calculate your pace per kilometer or mile and project estimated race times for 5K, 10K, Half Marathon, and Marathon using Peter Riegel's validated biomechanical model.

Hours
Minutes
Seconds
💡 Pacing tip: Riegel's formula (T2 = T1 × (D2 / D1)^1.06) assumes adequate aerobic base training for the target distance.
YOUR PACE & SPEED SUMMARY
--:-- min / km
--:-- min / mile
Average Speed -- km/h
400m Track Lap Time --

Equivalent Race Time Predictions

Distance Estimated Time Average Pace
🏃 Category: Sports & Performance

1RM Calculator (One-Rep Max & Maximum Strength)

Calculate your theoretical maximum strength (1RM) without risking joint injury under maximal loads. Uses validated scientific formulas from Epley, Brzycki, Lander, and Lombardi with training zone percentages.

💡 Accuracy tip: Formulas are exceptionally reliable with sets between 2 and 6 reps. Above 10 reps, metabolic fatigue endurance reduces 1RM estimation accuracy.
YOUR ESTIMATED MAXIMUM STRENGTH
93.3 kg (1RM)
Theoretical maximum load for one complete repetition

Load Percentages and Training Zones Table

% of 1RM Load (kg) Est. Reps Training Zone

Scientific 1RM Formula Methodology

Indirect 1RM estimation eliminates joint shearing stress and injury risks associated with direct maximal lifts. The equations utilized represent the most validated formulas in sports biomechanics:

  • Epley (1985): 1RM = Weight × (1 + 0.0333 × Reps). The worldwide gold standard for sub-maximal sets of 3 to 10 repetitions.
  • Brzycki (1993): 1RM = Weight × (36 / (37 - Reps)). Highly accurate for compound pressing and pulling lifts.
  • Lander (1985): 1RM = (100 × Weight) / (101.3 - 2.67123 × Reps). Models conservative neural recruitment profiles.
  • Lombardi (1989): 1RM = Weight × Reps^0.10. Applicable to explosive multi-joint lifts.
⚠️ Practical Limitations:

Calculations assume the set was executed close to muscular failure (RPE 9-10 / RIR 0-1) with textbook form. If multiple repetitions were left in reserve (RIR > 2), the calculated 1RM will underestimate your true maximal capacity.

Frequently Asked Questions on 1RM

Is testing an actual 1RM max lift necessary?

Unless you compete in powerlifting, NO. True 1RM testing creates severe central nervous system fatigue lasting 7-10 days. A heavy 3-5 rep set provides an estimate within a 2% margin of error.

How do I program using 1RM percentages?

Use 85-90% for pure strength blocks (3-5 reps), 70-80% for muscle hypertrophy (8-12 reps), and 60-65% for power, speed, or muscular endurance.

🏃 Category: Sports & Performance

Scientific Steps to Calories Calculator (Walking, Walking Pad & Rucking)

Calculate exact walking energy expenditure with bioenergetic accuracy (ACSM metabolic equations) based on weight, height, speed, slope grade, and backpack load (Rucking).

Calculates stride
Rucking
💡 Personalized stride length: Your stride is calculated biomechanically by multiplying height by 0.414 (men) or 0.413 (women). For someone 175 cm tall, each step equals ~72.5 cm.
ENERGY EXPENDITURE & DISTANCE
-- kcal
Estimated total caloric burn
Distance covered -- km
Estimated active time --
Metabolic intensity -- METs
Calculated average stride -- cm

Real Impact on Body Composition

Equivalent body fat (~7,700 kcal/kg) ~0 g
Real food equivalence (bread slices / ~75 kcal) ~0 slices
Non-Exercise Activity Thermogenesis (NEAT) Optimal / Very High

Scientific Walking Energy Expenditure (ACSM)

Unlike basic pedometer apps applying an arbitrary "0.04 kcal per step" rule, this tool integrates the official walking oxygen consumption formula from the American College of Sports Medicine (ACSM):

VO₂ (ml/kg/min) = (0.1 × S) + (1.8 × S × G) + 3.5

Where S represents speed in m/min and G fractional gradient. Metabolic output is then converted to kilocalories based on body mass and additional backpack load (Pandolf equation modified for Rucking).

⚠️ Why Speed and Incline Matter:

Strolling 10,000 steps slowly (3 km/h / 1.9 mph) burns ~300 kcal for a 75 kg individual. The same 10,000 steps at a brisk walk (5.8 km/h / 3.6 mph) boosts burn to ~450 kcal, while rucking with a 10 kg backpack or incline easily surpasses 600 kcal with minimal knee impact.

Daily Steps & Caloric Burn FAQs

Are 10,000 daily steps strictly mandatory?

Epidemiological studies (Harvard University & Step-Count consortium) indicate longevity and cardiovascular benefits optimize between 7,500 and 8,500 daily steps, beyond which benefits continue at a steady rate.

Is an under-desk Walking Pad as good as outdoor walking?

Both burn identical calories at equal speeds. Walking Pads allow accumulating 5,000-10,000 steps during remote work, while outdoor walking provides circadian benefits from morning natural light.

💰 Category: Personal Finance

Compound Interest & Savings Growth Calculator

Discover the power of exponential long-term growth. Simulate how regular monthly deposits combined with compounding returns multiply your net worth over time.

20 years
8.0%
Historical reference for global index funds (MSCI World / S&P 500): 7% - 9% nominal.
PROJECTION AT END OF TERM
-- €
Total accumulated wealth
Total capital contributed -- €
Total interest earned -- €
Principal contributed (50%) Compound interest profit (50%)

Milestone Timeline Breakdown

Term Contributed Interest Total
💰 Category: Personal Finance

Mortgage Payment & Total Loan Cost Calculator

Calculate your monthly mortgage installment using standard French amortization, the total interest paid over the loan term, and estimated home buying closing costs.

Typically up to 80% of property appraisal or purchase value.
25 years (300 months)
2.80%
Fixed rate or Euribor + margin estimate for variable loans.
💡 30% Financial Rule: Analysts recommend keeping your monthly mortgage payment below 30% - 35% of household net income to avoid over-indebtedness.
PAYMENT SUMMARY & TOTAL COST
-- € / month
Estimated monthly payment
Total interest paid to bank -- €
Total amount repaid -- €
Borrowed principal (75%) Bank interest (25%)

Estimated Home Closing Costs & Taxes

Approximate savings needed (for a property matching loan + 20% down payment):

Recommended down payment (20%) -- €
Property transfer taxes (~8% resale or 10% new build VAT) -- €
Notary, Registry, Gestoria & Appraisal (~1.5%) -- €
Recommended Savings Cushion (~30%) -- €
💰 Category: Personal Finance

Net Salary & Progressive Tax Bracket Calculator (Spain)

Calculate your exact net salary from gross annual pay, tax withholdings, and Social Security contributions. Understand how Spain's progressive tax brackets work and debunk tax bracket myths.

Contracted annual salary before taxes and deductions.
📖 Recommended reading: To understand why earning more never results in taking home less, read our guide on Progressive Tax Brackets and Salary Myths.
YOUR PAYCHECK BREAKDOWN
-- € / mes
Net Monthly Salary
Income Tax (Effective Rate) --%
Social Security (6.35%) -- €/año
Net in bank (75%) Income Tax (18%) Soc. Security (7%)

Progressive Tax Brackets Breakdown

Salary Bracket Rate Taxable in Bracket Tax Owed
🥗 Category: Health & Nutrition

Body Fat Calculator (US Navy Method)

Estimate your body fat percentage, fat mass, and lean body mass with scientific accuracy using the official US Navy anthropometric method (Hodgdon & Beckett).

Measure at the narrowest point below the larynx.
At navel level for men; at the narrowest waistline for women.
Estimated Body Fat % -- --
Lean Body Mass -- Masa libre de grasa (músculo, huesos y órganos)
Fat Mass -- Masa grasa total en el cuerpo
American Council on Exercise (ACE) Standards
Category Men Women
Essential Fat 2 - 5% 10 - 13%
Athletes 6 - 13% 14 - 20%
Fitness 14 - 17% 21 - 24%
Acceptable / Average 18 - 24% 25 - 31%
Higher Fat / Obese ≥ 25% ≥ 32%

Why the US Navy Tape Method Outperforms Bioimpedance Scales

Home bioimpedance scales fluctuate dramatically depending on hydration, meal timing, and sodium intake. The Hodgdon & Beckett equations adopted by the US Department of Defense correlate within a 3-4% margin of error compared to DEXA scans through simple, reproducible tape measurements.

🏃 Category: Sports & Performance

Hyrox Race Time & Splits Estimator

Simulate your complete Hyrox race (8 km of running + 8 functional strength stations) accounting for cumulative fatigue and Roxzone transition times.

:
Your standard 5K/10K flat running pace without fatigue.
Total Estimated Time -- Tiempo total estimado en carrera
Total Running (8 km) --
Total 8 Stations --
Total Roxzone --
# Segment / Station Official Load Estimated Split

Hyrox Pacing and Energy Management

Hyrox is an endurance race with strength interferences. Maintaining controlled breathing and steady aerobic pacing on the first 3 km ensures sufficient glycogen reserves for the Sled Pull and Burpee Broad Jumps.

🥗 Category: Health & Nutrition

Sleep Cycles Calculator (90-Minute Rule)

Calculate the optimal times to fall asleep or wake up respecting 90-minute ultradian sleep cycles to eliminate sleep inertia and wake up energized.

Recommended Wake-up / Bedtime Schedule

Waking at the end of a cycle ensures a smooth transition from REM sleep to alertness:

The Neurobiology of 90-Minute Sleep Cycles

Sleep cycles oscillate between non-REM deep restorative slow-wave sleep and REM sleep. Waking mid-cycle causes sleep inertia, leaving you feeling groggy regardless of total hours slept.

💰 Category: Personal Finance

50/30/20 Budget & Savings Calculator

Organize your net income with Elizabeth Warren’s financial rule: 50% for essential needs, 30% for lifestyle, and 20% for future savings and compound investment.

Total net take-home pay deposited into your account.
Reparto 50 / 30 / 20
50% Necesidades 30% Deseos 20% Ahorro e Inversión
50% Essential Needs -- Housing, utilities, groceries, healthcare, mandatory transport, and essential insurance.
30% Lifestyle & Wants -- Dining out, entertainment, subscriptions, hobbies, travel, and personal shopping.
20% Savings & Investing -- Emergency fund, global index funds (ETFs), debt pre-payments, and retirement accounts.
Compound Wealth Projection (7% Annual Return)
10-Year Wealth Projection: --
20-Year Wealth Projection: --

Why the 50/30/20 Budget Works for Financial Independence

By automating the 20% savings rule directly into index funds at the beginning of the month, compound growth builds lasting financial freedom without extreme deprivation.

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