TL;DR
For one clear target weight with nothing to sign up for, use the Calc Garden ideal weight calculator: enter your height and it shows a Devine-formula target alongside the healthy BMI weight range from 18.5 to 24.9, the instant you type. If you want to compare several formulas side by side, the Calculator.net ideal weight calculator shows four at once and Omni shows six. This is not an "only free one" claim: Calculator.net, Omni and Yazio all offer free ideal weight calculators too. The real choice is one clean answer versus a fuller table of formulas.
What the Calculator.net ideal weight tool does well
Calculator.net's ideal weight calculator is a capable free tool, and it is worth saying so plainly before positioning anything against it. It asks for your age, sex and height, then shows four established formulas at once: Robinson (1983), Miller (1983), Devine (1974) and Hamwi (1964), plus a healthy weight range based on the World Health Organization BMI band. Seeing all four numbers together is genuinely useful if you want to understand how much the estimates disagree, and the page explains each formula underneath. It has no signup and costs nothing.
The trade-off is that four formulas produce four different answers, and for most people the extra numbers are noise rather than signal. If your question is simply "roughly what should I weigh for my height," a table of Robinson, Miller, Devine and Hamwi results asks you to pick between figures that were never meant to be that precise. That is where a simpler tool earns its place: not because Calculator.net is wrong, but because a single clear target inside a healthy range is often the more usable answer.
The ideal weight calculators compared
In the table a check means the tool does it cleanly, "Partial" means it does it with caveats, and a dash means it does not. The pricing row reflects each product as of 2026.
| Capability | Calc Garden | Calculator.net | Omni | Yazio |
|---|---|---|---|---|
| Price (as of 2026) | Free | Free | Free | Free |
| No signup or account to use | Yes | Yes | Yes | Partial |
| Ideal-weight formulas offered | Devine | Four | Six | BMI method |
| Gives one clear target, not a table | Yes | No | No | Yes |
| Shows a healthy BMI weight range | Yes | Yes | Yes | Partial |
| Shows the formula and working | Yes | Yes | Yes | No |
| Metric-first, UK friendly default | Yes | Partial | Partial | Partial |
| No app-download push | Yes | Yes | Yes | No |
| Runs entirely in your browser | Yes | Yes | Yes | Partial |
Read it honestly. Calculator.net and Omni win where you want breadth: they put four and six formulas in front of you, which is the better choice if you are comparing methods or want to see the spread. Yazio adds a current weight input and a slick interface, but it leans on its app and pushes a download. Calc Garden wins on a narrower promise: one Devine target, the healthy BMI range beside it, the formula shown, a metric-first default and no push to install anything. If you want the shortest path from height to a sensible number, it answers in one screen.
The ideal weight formula, and a worked example
Every one of these tools leans on the same family of formulas. The Devine formula, which Calc Garden uses, sets a base of 50 kg for men or 45.5 kg for women at a height of 5 feet, then adds 2.3 kg for each inch above that. Robinson, Miller and Hamwi keep the same shape and only change the base weight and the per-inch amount, which is why their answers cluster within a few kilograms. The healthy BMI range that sits alongside is your height in metres squared multiplied by 18.5 at the low end and 24.9 at the high end.
Calc Garden's ideal weight calculator lands with a worked example already filled in. Take a person of 178 cm. That is about 70.1 inches, so Devine gives 50 plus 2.3 times 10.1, which is roughly 73 kg for a man. The healthy BMI band for 1.78 m runs from about 59 kg to 79 kg, so the Devine figure sits comfortably inside it. Change the height and both the target and the range recompute instantly, so you can see how a couple of centimetres shifts the numbers without reaching for a second formula.
Why one clear target can beat a table of formulas
The formulas exist because clinicians needed a quick, repeatable way to estimate body weight, mostly to dose medication. None of them was designed to set a personal fitness goal, and none accounts for how much of your weight is muscle or how wide your frame is. Shown four or six of these at once, most people either average them in their head or pick the flattering one, neither of which is more accurate than a single well-chosen estimate.
A simpler tool sidesteps that. Calc Garden gives you the Devine number, the most widely cited of the set, and frames it inside the healthy BMI range so you are always reading it as a guideline rather than a verdict. The honest trade-off is that it will not lay four formulas side by side for you, because it is not trying to. If that comparison is exactly what you want, Calculator.net or Omni is the better fit, and both are free.
Which one to use
Reach for Calculator.net or Omni when you want to compare methods, see how far Robinson, Miller, Devine and Hamwi diverge, or work from age as well as height. Reach for Yazio if you like its interface and do not mind the app prompts. Any of them will give you a reasonable estimate for free.
Reach for the Calc Garden ideal weight calculator when you want one clear target and a healthy range, fast, with no signup and no clutter. From there, two tools take the picture further: the BMI calculator shows which category your current weight falls in, and the BMR and calorie calculator estimates the daily calories that would move you toward a target. For the wider set of explainers, the guides index collects the rest, including what is a good BMI and what is a healthy waist-to-height ratio.