---
title: "Free Fitness Calculators for Coaches & Athletes | Boost Fitness"
canonical_url: "https://boostfitness.io/tools"
last_updated: "2026-07-11T17:45:49.553Z"
meta:
  description: "Free fitness calculators for coaches and athletes: one rep max, macros and calories, BMI, and daily protein intake — with clear guidance on using each result."
  "og:description": "Free fitness calculators for coaches and athletes: one rep max, macros and calories, BMI, and daily protein intake — with clear guidance on using each result."
  "og:title": "Free Fitness Calculators for Coaches & Athletes | Boost Fitness"
---

Boost Fitness

# **Free fitness calculators for coaches and athletes**

Working calculators built on the same formulas coaches use every day — Epley and Brzycki for strength, Mifflin-St Jeor for calories, evidence-based protein ranges. No sign-up, no email gate. Each tool explains how the maths works and how to use the result in real programming.

**One Rep Max Calculator**

Estimate your 1RM from any set with the Epley and Brzycki formulas, plus a 50–95% loading table.

[One Rep Max Calculator](https://boostfitness.io/tools/one-rep-max-calculator)

**Macro Calculator**

Calories and macros for any goal — BMR (Mifflin-St Jeor), TDEE, and a protein/fat/carb split.

[Macro Calculator](https://boostfitness.io/tools/macro-calculator)

**BMI Calculator**

Body mass index in metric or imperial units, with NHS categories and honest limitations.

[BMI Calculator](https://boostfitness.io/tools/bmi-calculator)

**Protein Intake Calculator**

An evidence-based daily protein range (1.2–2.2 g/kg) for your body weight and goal.

[Protein Intake Calculator](https://boostfitness.io/tools/protein-intake-calculator)

## Why we built these

Boost Fitness is an all-in-one platform for personal trainers and online coaches — [nutrition coaching](https://boostfitness.io/features/nutrition), programming, client management and payments in one place. The calculators on this page use the same maths our coaches rely on when they prescribe calorie, macro, and training targets to clients. We've made them free for anyone to use, with honest notes on where each estimate holds up and where it doesn't.

If you coach clients for a living, the manual step disappears entirely: Boost Fitness calculates and assigns daily targets on each client's calendar automatically. See [pricing](https://boostfitness.io/pricing) or [how we compare to other platforms](https://boostfitness.io/compare), and start with a 30-day free trial.

## **Stop calculating targets by hand**

Prescribe calorie, macro, and training targets to every client automatically — tracked in a built-in food diary and programme builder. Start your 30-day free trial.

[Start your 30-day free trial](https://boostfitness.io/register) [Explore nutrition coaching](https://boostfitness.io/features/nutrition)