The best free fitness calculators, and where each one wins
I run one of the sites on this page, so read it with that in mind. I have still tried to write the version I would want to read: what each of these sites genuinely does better, where each one stops, and the narrow case where mine is the better choice.
Search for almost any fitness number and the same handful of sites come back. They are all free, they are all fast, and most of them have been right for longer than I have been building anything. They pay for themselves through ads, supplement sales, or a program they would like you to buy, which is a normal way to fund a free tool and worth knowing while you use one.
I am not going to tell you they are bad. For a single number, one time, one of them is very likely the faster answer, and the last section of this page says which one I would send you to. What follows is the honest read on all of them, mine included.
What the free calculator sites do better
Four things, and none of them are small.
Breadth I will never match
Between Calculator.net and Omni Calculator there are thousands of calculators. I have 77. If your question is unusual, one of them almost certainly has a page for it and I almost certainly do not.
Years of trust, and it shows in the results
Most of these sites have been correct and online for a decade or more. That is why they sit at the top of the page when you search, and it is a fair reason to trust them.
Instant, with nothing in the way
Load the page, type, get a number. No account, no interruption, no decision to make first. That is a real feature and it is the main reason people use them.
Strength Level has the best free ranking there is
Ranking your lift against a huge pool of real submitted lifts is the single stickiest thing in this category, and it belongs to them. I do use published population data where it exists, and grip strength here is scored against percentiles from a study of millions of adults. But my barbell bands are coarse on purpose, the one-rep max page says so on the page, and for barbell lifts theirs is the deeper comparison.
The nine sites you keep landing on
No prices here on purpose. They move, and I have not verified a single one at checkout, so quoting them would make this page wrong within a month.
- 01
Calculator.net
Breadth nothing else touchesThousands of calculators across every subject there is, with fitness as one shelf among many. It loads fast, it has been trusted for years, and it never asks you for anything.
Where it stops. You get the number and the formula behind it, and that is the visit. Nothing is kept, so the next question starts from an empty form.
- 02
Omni Calculator
The most polished library in the categoryA very large, genuinely well designed catalog, with clear notes and cited sources sitting under a lot of the calculators. If you want to understand the formula, this is often the nicest place to read it.
Where it stops. Each calculator is its own island. The height and weight you typed a minute ago do not follow you to the next one.
- 03
TDEECalculator.net
One page, several answers at onceIt bundles your BMR, your TDEE, a macro split and a goal adjustment into a single result, so you are not visiting four separate pages to assemble one picture. That is a real convenience and most of the category does not do it.
Where it stops. That bundle is the whole product. There is nothing to come back to in six weeks and compare your old numbers against.
- 04
Legion
The best reading around the numberTheir calculators sit inside long, heavily cited articles, and the writing is good. If you want the research context and not just the output, it is worth your time.
Where it stops. Legion sells supplements, so the path after the number generally runs toward a product. That is a normal way to fund free tools, and it is worth knowing while you read.
- 05
Strength Level
The stickiest free feature in the whole categoryEnter a lift and it ranks you Beginner through Elite against an enormous database of real submitted lifts. Nothing on my site beats that, and I am not going to pretend otherwise. If "where do I actually stand" is your question, this is the answer.
Where it stops. It tells you where you stand. It does not tell you what to change on Monday.
- 06
Symmetric Strength
The clearest free read on imbalanceIt scores each lift separately and shows you which ones are lagging, instead of flattening everything into one total. For finding a weak link, it is excellent.
Where it stops. Like Strength Level, it is a snapshot. Deciding what to do about the weak link is left entirely to you.
- 07
IIFYM
The macro calculator a lot of people started withFast and opinionated. It hands you a macro split without much ceremony, which is exactly what some people want.
Where it stops. The split does not travel with you. Change your bodyweight in three months and you are back at the same blank form, retyping everything.
- 08
Precision Nutrition
The most credentialed name on this listIt comes from an actual coaching education company, and the methodology writing behind the calculator is a level above most of the category.
Where it stops. The calculator is the front door to their certification and coaching programs, so it is built to be a single, well made stop.
- 09
ExRx
The reference library everyone else quotesAn exercise directory, strength standards, and formulas that other sites cite for a reason. It has been accurate for a very long time and it has earned the trust it has.
Where it stops. It is built for looking something up, not for keeping track of yourself, and the interface shows its age.
Every one of them stops at the number
That is the honest summary. They answer the question you typed and the visit ends. This site is built around what happens after the number, which is a real difference and also a smaller one than the breadth gap above.
| The moment | The free sites | Here |
|---|---|---|
| After you get the number | The visit is over | The result is saved and stays comparable to the last one |
| Typing your details again | Every calculator, every time | Your bodyweight, height and activity level carry across calculators |
| What the number means | The formula, usually well explained | A plain-English reading of your result and what to do next |
| Deciding what to run next | Up to you | 28 ordered flows that run the calculators in sequence |
| Asking an AI for a plan | Not what these sites set out to do | The plan is written against the results you already saved |
| Cost of the calculators | Free | Free, with the result shown before anything is asked of you |
Six things, each one checkable on the site
If any of these turn out not to be true when you use it, that is a bug in the product or a lie on this page, and either way I want to hear about it.
Your results are kept, and they stay comparable
Almost every calculator can save its result, and the pure reference pages are the exception because they have nothing to save. Saved results collect on one page with the history behind each one, so the number you get in March can be read against the one you got in January. Save without an account and it stays on that device. Sign in, which is free, and it follows you to any device you use.
Your inputs travel between calculators
There is a shared vocabulary behind the calculators for the values that keep coming up: bodyweight, height, body fat, activity level, maintenance calories, resting heart rate. A calculator publishes what it learns into that store and the next one prefills from it, so you type your weight once rather than on every page you open.
The result is translated, not just printed
Most of the calculators add a plain-language reading under the number: what it means for you specifically, and two or three concrete things you could do next. Not all 77 have one, and the reference pages like the glossary and the unit converter have nothing to interpret. A handful more put that reading in their own section on the page instead of the standard card. Where a reading exists it is written for a beginner, not for someone who already knows the formula.
The calculators are arranged into ordered flows
28 guided flows run a handful of calculators in a deliberate order, each step saying why it comes where it does. That is the difference between a shelf of tools and a route through them.
An AI plan built on your own numbers, not a blank form
When you generate a plan, the request carries the results you have actually saved, labeled as your real logged numbers, so the plan is written around them instead of around an average. Results that have gone stale drop out rather than being treated as current, and where you have saved nothing the plan is told nothing rather than being handed a guess. There is no plan button sitting under a calculator result, to be clear. The plan reads whatever you have saved at the moment you ask for one.
The number comes first, then the ask
No calculator here holds your result back for an email address or an account. You get the full number, and only after it do you see an invitation to save it or read more. If that ever changes, this paragraph is the thing to hold me to.
Three things the other sites do better than me
A comparison page that only flatters its author is an advert. These are the real gaps.
I am one person, and this site is young
There is no team here and no decade of track record. The sites above have both. If that matters to you, it should, and it is a perfectly good reason to use them instead.
77 calculators is not thousands
I built for the questions a beginner actually asks about training, food and bodyweight. Outside that, the big libraries win and it is not close.
My strength bands are rougher than Strength Level
The one-rep max page bands your lift and says so plainly on the page: rough guidance, not a published standard. If ranking against a large pool of real lifts is what you came for, use Strength Level and come back here for what to do with the answer.
Pick by what you are actually trying to do
- You want one number, one time
- Use whichever of the sites above ranks first. It will be faster than making an account anywhere, mine included.
- You want to know how your lift compares to other people
- Strength Level, then Symmetric Strength if you want to see which lift is holding you back.
- You want the research behind the formula
- Legion or Precision Nutrition write the best long-form context in the category. ExRx is the reference the rest of us check against.
- You are starting out and the numbers keep changing
- This is the case I built for. Run the calculators here, let them keep your results, and read the numbers against each other as your bodyweight moves.
If the last one sounds like you
Start with the calculators. They are free, the result shows up before anything is asked of you, and your numbers carry from one to the next. You can decide later whether any of the rest of it is worth your time.