Osmolar

Disclaimer

Educational calculators and articles. Not medical advice.

Short version: Osmolar is an educational reference. Its calculators and articles are not medical advice and do not replace a clinician, pharmacist or your institution’s protocols. The calculators run in your browser and do not store or send the values you enter. Osmolar sets no tracking or advertising cookies.

Educational use only

Osmolar explains osmolarity and osmolality and provides calculators for students, educators and healthcare professionals. Everything on the site is for education and general information. Nothing here is a diagnosis, a treatment plan or a recommendation for an individual patient.

Not medical advice

Reading this site does not create a clinician–patient relationship. If you have questions about your own health or test results, talk to a doctor, nurse or pharmacist who knows your situation. Do not start, stop or change any treatment because of something you read or calculate here.

Calculators are calculation aids

Every calculator gives an estimate from the formula and inputs shown on its page. It does not make dosing or treatment decisions. In particular, our calculators do not recommend:

  • which fluid, feed or product to give;
  • volumes, infusion rates or correction targets;
  • insulin, antidote or dialysis decisions.

Results depend on the formula chosen, the units entered and the accuracy of the inputs. Each tool shows its formula, units, rounding and alternatives so that you can check the arithmetic yourself.

Follow your institution, pharmacist and clinician

Before any result informs care, check it against your institution’s protocols and with the responsible pharmacist or clinician. Local policies take precedence over this site.

Thresholds vary. Cut-offs on this site are commonly used reference points, not universal rules. For example:

  • The 900 mOsm/L figure printed on some parenteral nutrition product labels is a convention, not a rule. Institutional policies vary, and the ASPEN recommendation that cites it is graded weak.
  • A normal osmolal gap does not exclude toxic alcohol ingestion.
  • Reference ranges vary by laboratory. Read a result against the range printed on the lab report.

Emergencies

This site cannot help in an emergency. Call your local emergency number if someone collapses, has a seizure, has trouble breathing or can’t be woken. If you think someone has swallowed a poison or chemical, call your local emergency number or contact your local poison centre straight away.

US only: Poison Help 1-800-222-1222 (free, 24/7; poison.org, poisonhelp.hrsa.gov).

How the calculators handle your data

What follows describes how the site is set up at launch, as of the date at the top of this page.

  • Calculations run in your browser. The numbers you type are processed by code on your own device. They are not submitted to a server, and they are not added to the page address (URL).

  • Nothing you enter is stored by us. The calculators do not save inputs or results in cookies, local storage or any database. Values disappear when you close or reload the page. Your browser’s own features, such as form autofill, are controlled by your browser settings, not by us.

  • Osmolar sets no tracking or advertising cookies. Our host, Cloudflare, may set a strictly necessary security cookie (e.g. cf_clearance) [5]. The site shows no ads.

  • Analytics: Cloudflare Web Analytics only. We use it to count page views in aggregate and to measure how fast pages load. We do not use Google Analytics or any advertising or tracking service. According to Cloudflare’s documentation:

    • it does not use cookies, local storage or other data stored in your browser [1, 2], and does not fingerprint visitors by IP address, browser details or other data [1];
    • Cloudflare states that it does not collect or use visitors’ personal data [3];
    • its script collects page-load and responsiveness timings (such as Core Web Vitals), browser memory and timing measurements, the page address, the referring page address and, for slow-loading parts of a page, a description of the page element and resource involved [1, 2]. The dashboard can show visits by browser, operating system and country [1]. The IP address that reaches Cloudflare with each report is discarded at the nearest data centre and is not stored in its core databases or logs [2];
    • it does not currently log URL query strings [4];
    • Cloudflare keeps the unsampled analytics data for 7 days, then keeps an aggregated sample of about 10% for long-term storage; site owners can view data for the previous six months [4];
    • the analytics script is loaded from Cloudflare (static.cloudflareinsights.com) and sends its reports to Cloudflare (cloudflareinsights.com) [4].

    The analytics script does not read what you type into a calculator, and calculator inputs are not part of the page address.

  • Hosting. Like any website, our hosting provider (Cloudflare) receives standard technical information when your browser requests a page, such as your IP address, browser type and the page requested. Calculator inputs are not part of these requests.

  • External links. Source links open other websites (for example PubMed, DailyMed or MedlinePlus), which have their own privacy policies.

Changes. A consent banner will appear before any non-essential cookies, Google Analytics (GA4) or ads are ever added, so that they load only after you agree. We will update this page before any such change goes live.

Sources for this section (Cloudflare documentation, accessed 2026-10-18):

  1. Cloudflare. Web Analytics: Core Web Vitals. https://developers.cloudflare.com/web-analytics/data-metrics/core-web-vitals/
  2. Cloudflare. RUM beacon for Web Analytics (Data collection; Data processing; Privacy information). https://developers.cloudflare.com/speed/observatory/rum-beacon/
  3. Cloudflare. Web Analytics: About. https://developers.cloudflare.com/web-analytics/about/
  4. Cloudflare. Web Analytics: FAQ (“Is the data sampled?”; “What is the period of time I can access data in Web Analytics?”; “Does Cloudflare Web Analytics support UTM parameters?”). https://developers.cloudflare.com/web-analytics/faq/
  5. Cloudflare. Cloudflare Cookies. https://developers.cloudflare.com/fundamentals/reference/policies-compliances/cloudflare-cookies/

Osmolar is independent and not sponsored. It may earn money from affiliate links, which are disclosed on the page. If you buy something through an affiliate link, we may earn a commission at no extra cost to you. As of the date above, the site carries no affiliate links. The site shows no ads at launch; if that changes, ads would load only after consent, and this page would be updated first.

Any affiliate links will be limited to exam-preparation courses (nursing, pharmacy and medical), textbooks and books, and adult sports and electrolyte brands (not oral rehydration solutions marketed for illness, and nothing for infants or children). We do not use affiliate links for osmometers or other laboratory equipment.

When affiliate links appear:

  • a short disclosure is shown above the first affiliate link on that page;
  • affiliate links are labelled as affiliate links (and tagged rel="sponsored" for search engines);
  • affiliate links sit in a separate, labelled box at the end of selected articles, never on calculator pages, and never inside the article text, data or comparison tables, or calculator results. They are not recommendations of a product for any individual’s care.
  • after you click an affiliate link, the affiliate network or retailer may set its own cookies; Osmolar does not control these, and their privacy policies apply.

Commercial relationships do not affect medical content. Formulas, numbers, ranges and rankings are decided by our editorial and Medical QA process, not by partners or advertisers. No ads or affiliate units appear on calculator pages or inside data or comparison tables, and patient-facing pages carry no affiliate links. Sponsored content, if any, is labelled “Sponsored”, and any future sponsorship will carry its own disclosure. See How we check content for our full independence policy.

Accuracy and corrections

We check every formula, number and claim against its cited source, using primary sources wherever they exist, and each page shows its sources, the date it last passed Medical QA (“Last checked”) and its last-updated date. No clinician has reviewed the content. Even so, errors are possible, guidelines and product labels change, and a page may lag behind the newest evidence. Information is provided as is, without any guarantee that it is complete, current or suitable for a particular use.

If you find an error, please tell us. How we check content and handle corrections is described on the How we check content page.

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