Free Calculators, Formulas You Can Check

No sign-up, no clutter — just the number you came for, calculated from a sourced formula and verified by hand before it went live.

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One Rep Max (1RM) Calculator

Estimate the heaviest weight you could lift for a single rep, based on a set you've already done.

Coast FIRE Calculator

Find out if your current savings alone could grow into full financial independence by retirement age.

IVF Due Date Calculator

Estimate your due date and key pregnancy milestones from your embryo transfer date.

FFMI Calculator

Work out your normalized Fat-Free Mass Index and see how your muscularity compares to natural and enhanced lifters.

Car Loan Payoff Calculator

See how many months and how much interest you'll save by putting extra money toward your auto loan each month.

Car Depreciation Calculator

Estimate how much your car's value will drop over the next few years.

Debt Snowball Calculator

Enter each debt and see exactly how many months to debt-free, and how much interest you'll pay, with the debt snowball method.

PTO Accrual Calculator

Project your paid time off balance at a future pay period, based on your current balance and accrual rate.

Browse by Category

Health & Fitness

Strength, cardio, and nutrition numbers.

8 calculators

Finance

FIRE planning, debt payoff, investing, and real estate.

12 calculators

Pregnancy & Baby

Due date estimates for fertility treatment timelines.

2 calculators

Home & DIY

Sizing, cost, and payback math for house and yard projects.

4 calculators

Food & Nutrition

Ratio math for baking and brewing.

3 calculators

Sports & Hobbies

Scoring systems and gear math for tabletop, lanes, and the range.

3 calculators

Auto

Depreciation and loan payoff for car ownership.

2 calculators

Productivity & Work

Time off balances and true employee cost.

2 calculators

Beauty & Personal Care

Skin, sun exposure, and personal care questions.

1 calculator

Why TrueCalc

Most calculator sites optimize for ad space, not accuracy. We do the opposite: every formula on this site is traced back to a named source — a published study, an official standard, or a well-documented convention — checked by hand against a known example, and tested in a real browser before it's published. No account, no email gate, no walls of ads between you and your answer. See exactly how we do it on our accuracy page.