Metformin Dose Conversion Made Simple

If you’ve been told to change your Metformin strength, you probably wonder how many tablets to take now. The good news is you don’t need a pharmacy degree to do the math. Below is a quick way to convert any Metformin dose – whether you’re moving from 500 mg to 850 mg, or from a daily to a weekly schedule.

Basic Conversion Formula

All Metformin tablets come in a set of standard strengths: 500 mg, 850 mg, and 1000 mg. To find the new number of tablets, use this simple formula:

New tablets = (Current total daily mg ÷ New tablet strength)

Round the result to the nearest whole tablet unless your doctor says otherwise. For example, a 1500 mg daily dose using 500 mg tablets equals three tablets. If you switch to 850 mg tablets, divide 1500 by 850 – you get about 1.76, so you’d take two tablets (1700 mg) or one tablet (850 mg) plus a half‑tablet if your pharmacy can split it.

Switching Between Immediate‑Release and Extended‑Release

Immediate‑release (IR) Metformin is taken two or three times a day, while extended‑release (XR) is usually once daily. The total milligram amount stays the same; only the timing changes.

To move from IR to XR, add up all the IR tablets you take in a day and match that total with an XR tablet of the same strength. If you’re on 500 mg IR twice a day (1000 mg total), you can switch to one 1000 mg XR tablet. If the XR strength you need isn’t available, combine the closest strengths (e.g., 850 mg XR + 150 mg IR) and follow your doctor’s advice.

When you change the schedule, keep an eye on how you feel. Some people notice mild stomach upset with XR at first, but it usually settles within a week.

For quick reference, here’s a handy conversion table:

Current Daily mg → New Tablet Strength → New Tablet Count
500 mg → 850 mg → 1 tablet (850 mg) – increase by 350 mg
1000 mg → 850 mg → 1 tablet + 1/2 tablet (≈1275 mg) – discuss split with pharmacist
1500 mg → 1000 mg → 1½ tablets (1500 mg) – use a 1000 mg tablet + 500 mg tablet
2000 mg → 850 mg → 2½ tablets (2125 mg) – adjust as doctor directs

Remember, never change your Metformin dose without talking to a healthcare professional. They’ll confirm the right amount for your kidney function, blood sugar goals, and any other meds you’re taking.

Need a fast calculation on the go? Just plug your current total mg into the formula above and you’ve got the answer in seconds. Keep this guide handy in your medicine cabinet, and you’ll never be stuck wondering how many pills to take again.