About this calculator

What it is

A calculator. It turns a dose written in milligrams, micrograms or units into a mark on an insulin syringe, for medications supplied in vials. Its presets are read from the FDA labels of approved products and contain only what the label says about the vial: the amount in it, the fill or diluent volume, the concentration. They never contain a dose. For any other vial it does the same arithmetic on numbers you type.

What it is not

It is not medical advice and it is not a substitute for the instructions that came with your medication or for your pharmacist. It has not been reviewed, cleared or approved by the FDA. Team Read the Mark designed the calculator around its reading of the FDA's guidance on clinical decision support software, which places transparent arithmetic tools that originate no dose and show their working among the low-risk software the agency has said it does not intend to regulate as a device. That is our interpretation, not an FDA determination.

Why it exists

When this site was built, most of the calculators that came up for these searches were widgets on storefronts, several of them selling products the FDA has not approved. None drew the syringe. None showed the millilitres beside the mark. None refused to name unapproved products. Most pre-filled a dose. We wanted a tool whose arithmetic, sources and limitations anyone can inspect, and that meant building one that does less: arithmetic, the drawing, the read-back, and nothing that could be mistaken for a recommendation.

How it is checked

No clinician reviews this site. Every preset is read from the FDA label linked on the sources page, with the date it was last read, and the arithmetic is checked against worked examples before every update. Treat the result as arithmetic on the numbers you typed, and confirm every draw with your pharmacist.

The arithmetic is checked automatically against worked examples before every update, and those examples are published on the how it works page. Every preset value links to the label it was read from on the sources page, with the date it was last read. When a label changes or a preset is re-read, it is recorded on the changelog.

How it is funded

At the moment it is not. There are no advertisements, no referral links and no sponsors. If that changes, two kinds of funding may appear, each disclosed where it appears: referral fees from mainstream retailers of injection supplies such as syringes and sharps containers, and non-personalised display advertising kept away from the calculator and its result. Neither would touch the calculation, which is the same for everyone.

Three things will not be added. Money from vendors of unapproved compounds, in any form. Referral links to prescribers of compounded GLP-1 products, at least until the regulatory position on those products is settled. And any feature that stores what you take or suggests what you should.

Who made it

The site is built and maintained by Team Read the Mark, working from India for a mostly US audience. It is a small independent project with no ties to any pharmaceutical company, compounding pharmacy or vendor. The rules for what may and may not appear on the site are listed on the how it works page and the medications page.

Contact

Use the report-a-problem form. It reaches a monitored inbox. Reports about the arithmetic are answered within two working days, and fixes are noted on the changelog. Report a problem.