F*CK Getting Old

All Calculators

12 free calculators for peptide dosing, metabolic health, strength, sleep, and alcohol — what each one does, how it works, and who it’s actually for. No account required for any of them.

RESEARCH & INFORMATIONAL USE ONLY

Every calculator below is for informational and research purposes only and is not medical advice. Results are estimates based on standard formulas, not a diagnosis or a prescription. Consult a licensed healthcare provider before making decisions based on any calculator result.

Peptide Dosing

Reconstitution Calculator

What it is: Converts a peptide vial size, bacteriostatic (BAC) water volume, and desired dose into the exact number of units to draw on an insulin syringe.

How it works: Enter vial size in mg, BAC water added in mL, and your desired dose in mcg or mg. It instantly returns the concentration (mcg/mL), the units to draw, and the equivalent volume in mL — plus quick-select presets for common peptides.

Who it’s for: Anyone reconstituting and dosing injectable peptides who wants to skip manual math and avoid draw errors.

Source

Standard compounding-pharmacy concentration math (concentration = vial mg × 1000 ÷ mL of BAC water) and the U-100 insulin syringe convention (100 units = 1 mL). This is arithmetic, not a cited study or a dosing recommendation.

For research and informational purposes only. Always double-check the math yourself and consult a licensed professional before dosing anything.

Open Reconstitution Calculator →

Metabolic Health

TDEE / Calorie Calculator

What it is: Estimates your Total Daily Energy Expenditure — the calories you burn per day at your current activity level — using the Mifflin-St Jeor equation.

How it works: Enter sex, age, height, weight, and activity level. It returns your estimated BMR (resting burn) and maintenance calories.

Who it’s for: Anyone setting a calorie target for cutting, maintaining, or building muscle instead of guessing.

Source

Mifflin-St Jeor equation for BMR (Mifflin MD, St Jeor ST, et al., "A new predictive equation for resting energy expenditure in healthy individuals," American Journal of Clinical Nutrition, 1990), scaled by standard activity multipliers (1.2–1.9) used widely in dietetics and sports nutrition.

An estimate based on population averages — individual metabolism varies. Adjust based on real-world results after a few weeks.

Open TDEE / Calorie Calculator →

Protein Calculator

What it is: Estimates a daily protein target in grams based on your bodyweight and training goal.

How it works: Enter your bodyweight and whether you’re cutting, maintaining, or building. It returns a gram target using standard sports-nutrition ratios.

Who it’s for: Anyone training for muscle gain, fat loss, or general strength who wants a concrete number instead of a vague "eat more protein."

Source

Grams-per-pound-of-bodyweight ranges consistent with sports-nutrition guidance such as the International Society of Sports Nutrition's position stand on protein and exercise (Jäger et al., 2017), scaled by training goal.

Open Protein Calculator →

Body Fat Estimator

What it is: Estimates body fat percentage using the US Navy circumference method.

How it works: Enter height, neck, and waist measurements (plus hip, for women). It returns an estimated body fat percentage.

Who it’s for: Tracking body composition trends over time without access to calipers or a DEXA scan.

Source

US Navy circumference method (Hodgdon JA, Beckett MB, "Prediction of Percent Body Fat for U.S. Navy Men and Women," Naval Health Research Center, 1984). Category labels (athletic, average, etc.) follow commonly cited ACE-style body-fat ranges.

A tape-measure estimate, not a clinical measurement — most useful for tracking your own trend over months, not as an exact number.

Open Body Fat Estimator →

Strength & Training

One-Rep Max Calculator

What it is: Estimates your one-rep max (1RM) from any working set, using the Epley formula.

How it works: Enter the weight you lifted and the reps you performed. It returns your estimated 1RM plus a %1RM table for programming (e.g. weights for 5x5 or 3x3 work).

Who it’s for: Lifters programming strength work off percentages who don’t want to max out every session to know their numbers.

Source

Epley formula (Epley B., 1985): 1RM = weight × (1 + reps ÷ 30). One of several widely used 1RM estimation formulas; accuracy drops at higher rep counts (above ~10-12 reps).

Open One-Rep Max Calculator →

Heart Rate Zone Calculator

What it is: Calculates heart rate training zones, including Zone 2, using the Karvonen method.

How it works: Enter your age and resting heart rate. It returns target heart rate ranges for each training zone.

Who it’s for: Anyone doing zone-based cardio — Zone 2 for aerobic base building, higher zones for intervals.

Source

Karvonen method (Karvonen MJ, Kentala E, Mustala O, "The Effects of Training on Heart Rate," Annales Medicinae Experimentalis et Biologiae Fenniae, 1957), using the commonly cited age-predicted max heart rate estimate (220 − age), itself a population-average approximation.

Open Heart Rate Zone Calculator →

Sleep

Sleep Debt Calculator

What it is: Estimates your accumulated weekly sleep debt.

How it works: Enter your target hours of sleep per night and your typical actual hours. It returns your weekly sleep deficit.

Who it’s for: Anyone who suspects they’re chronically under-sleeping and wants an actual number to look at.

Source

Simple arithmetic against a target you set yourself. The commonly cited adult recommendation of 7-9 hours/night (from bodies like the CDC and National Sleep Foundation) is offered only as a starting default, not enforced.

Open Sleep Debt Calculator →

Sleep Quality Score

What it is: A quick self-assessment of last night’s sleep quality.

How it works: Answer a few questions about how long it took you to fall asleep, how often you woke up, total duration, and how you felt on waking. It returns a quick quality score.

Who it’s for: Spot-checking sleep quality without a wearable or sleep-tracking app.

Source

An original point-based scoring model built around four domains commonly used in sleep research — latency, night wakings, duration versus target, and morning feeling — in the same spirit as instruments like the Pittsburgh Sleep Quality Index (PSQI). It is not the PSQI and has not been clinically validated.

Open Sleep Quality Score →

Alcohol

Alcohol Use Self-Screening (AUDIT-C)

What it is: A validated 3-question screener for whether a drinking pattern is worth a closer look — not a diagnosis, but the same tool a doctor might use.

How it works: Answer three questions about frequency, typical quantity, and how often you have 6+ drinks in one sitting. It returns a 0-12 score and what that range commonly indicates, plus resources if the score is elevated.

Who it’s for: Anyone unsure whether their drinking is "normal" and wants an actual reference point instead of a gut feeling.

Source

AUDIT-C, the 3-question consumption subset of the WHO Alcohol Use Disorders Identification Test, validated as a standalone screener (Bush K, et al., "The AUDIT Alcohol Consumption Questions," Archives of Internal Medicine, 1998). Sex-specific positive-screen cutoffs (men ≥4, women ≥3) per Bradley KA, et al., 2007.

A screening tool, not a diagnosis. If you drink heavily and daily, stopping abruptly can be medically risky — that's a conversation for a doctor, not a self-directed plan.

Open Alcohol Use Self-Screening (AUDIT-C) →

Standard Drink Calculator

What it is: Calculates how many US standard drinks (0.6 fl oz / 14g of pure alcohol) are in a given pour.

How it works: Enter the volume and ABV% of what you’re drinking. It returns the standard drink count.

Who it’s for: Anyone trying to track alcohol intake accurately — a single "drink" varies a lot by pour size and ABV.

Source

NIAAA (National Institute on Alcohol Abuse and Alcoholism) definition of a US standard drink: 0.6 fl oz (14g) of pure alcohol.

Open Standard Drink Calculator →

Weekly Drinks & Calories

What it is: Estimates weekly calories from alcohol and compares your intake to the NIAAA low-risk drinking guideline.

How it works: Enter your typical weekly drink count. It returns estimated calories and how that compares to the guideline.

Who it’s for: Anyone watching how much alcohol is actually contributing to their weekly calorie total.

Source

NIAAA low-risk drinking guideline (14 drinks/week for men, 7 for women, with daily caps of 4 and 3 respectively — the daily cap isn't captured by this weekly tool). Calories are estimated at ~100 kcal per standard drink, a commonly used rough approximation — mixers and sugar content add more.

Open Weekly Drinks & Calories →

Labs

Lab Reference Checker

What it is: Checks lab values — testosterone, cholesterol, glucose, and more — against commonly cited reference ranges.

How it works: Enter a value for any supported marker. It shows where that value falls relative to commonly cited ranges. Nothing you enter is saved — it’s client-side only and gone on refresh.

Who it’s for: Making sense of a lab report between doctor visits.

Source

General adult reference ranges commonly cited across major lab providers and standard clinical references (e.g. LabCorp, Quest Diagnostics, Mayo Clinic Laboratories). Every lab sets its own exact range, printed on your results — treat these as a general orientation, not your lab's authoritative range.

Reference ranges vary by lab and population. This is not a diagnosis — discuss any results with a licensed provider.

Open Lab Reference Checker →

Want the full walkthrough, including how to save a result straight to your dosing schedule? Read How to Use Every Calculator on F*CK Getting Old on the blog.