Fitness calculators

Four calculators that show their working. They run the same equations as the Phasebuilt plan builder, entirely in your browser, with no account and nothing sent to a server.

Calorie calculatorYour BMR, maintenance calories and a daily target for your goal, using the Mifflin St Jeor equation.Protein calculatorA daily protein target in grams from your bodyweight and goal, split across your meals.Macro calculatorYour calories split into protein, carbohydrate and fat, anchored to bodyweight rather than a fixed ratio.One rep max calculatorEstimate your 1RM with the Epley and Brzycki formulas, plus a full training percentage table.

The same arithmetic as the plan builder

These are not separate implementations. Every figure here comes from the equations the Phasebuilt plan generator itself runs, so a calculator and a finished plan built from the same inputs will always agree. Where a number is an estimate, each page says so and shows the working rather than presenting a total as fact.

Nothing you enter is collected

All four tools run entirely in your browser. There is no account, no server call and no analytics on this site, so your bodyweight and training numbers stay on your own device. See the privacy policy for exactly what that means.

Where the numbers come from

Calorie figures use the Mifflin St Jeor equation, published in the American Journal of Clinical Nutrition in 1990. Protein targets sit inside the 1.4 to 2.0 g per kg range the International Society of Sports Nutrition gives for physically active people. One rep max estimates use the Epley and Brzycki formulas. The guides work through each method in full.

Turn this into a 90-day plan

Free, no account, and it runs entirely in your browser.