What does the DRG calculator do?

It groups an inpatient stay the way CMS's MS-DRG grouper does: the principal diagnosis, the secondaries with their POA indicators, the ICD-10-PCS procedures and the discharge status go in, and the MS-DRG comes out, medical or surgical, including pre-MDC cases such as transplants, ECMO and tracheostomy. It shows which procedure and which secondary set the DRG, why every other secondary did or did not count, the DRG family with relative weights, and what a documented CC or MCC would change.

Yes. A whole inpatient claim per check, the principal plus up to 24 secondaries and 25 procedures, with the complete grouper logic and no account required. The paid workspace carries the same codes into the conflict check, Medicare coverage policy and HCC scoring, keeps your work, and takes up to 50 of each.

Does it group surgical DRGs?

Yes. Enter the ICD-10-PCS codes, principal procedure first. A stay with an operating-room procedure groups surgically: the grouper ranks the procedures by CMS's surgical hierarchy for the principal diagnosis's MDC, and a procedure unrelated to that MDC lands the stay in DRGs 981–989, exactly as CMS assigns them.

Which CMS version does it use?

MS-DRG v44, effective for discharges from October 1, 2026, with the FY 2027 IPPS Table 5 relative weights. The grouping is our port of CMS's own Java grouper software, checked against it on tens of thousands of claims with no differences. Both versions are printed under every result.

Free tool

Free DRG calculator

Enter the diagnoses with their POA indicators and the procedures, and get the MS-DRG CMS assigns, medical or surgical, with the procedure and the secondary that set it, the DRG family with its weights, and what a documented CC or MCC would be worth. No signup, no card, no email.

Free for a whole inpatient claim: the principal plus 24 secondaries and 25 procedures. We do not store what you enter, and please do not enter patient identifiers: we do not need them and do not want them.

How the DRG is assigned

1Pre-MDC first, then the principal diagnosis’s MDC. Transplants, ECMO and tracheostomy with long ventilation are checked before anything else; otherwise the principal diagnosis picks the MDC: pneumonia lands in MDC 4.
2An operating-room procedure makes it surgical. The procedures are ranked by CMS’s surgical hierarchy for that MDC and the highest one picks the surgical class; an O.R. procedure unrelated to the MDC goes to DRGs 981–989. Without one, the stay groups medically.
3Each secondary is checked against the CC and MCC lists, the exclusion list for the principal, the DRG’s own definition, and the hospital-acquired-condition rules for anything not present on admission.
4The highest counting secondary decides the split. One reportable MCC puts the stay in the with-MCC DRG; the result shows the weight gap to the next split so a CDI query is a decision, not a hunch.

Common questions

What does the DRG calculator do?: It groups an inpatient stay the way CMS's MS-DRG grouper does: the principal diagnosis, the secondaries with their POA indicators, the ICD-10-PCS procedures and the discharge status go in, and the MS-DRG comes out, medical or surgical, including pre-MDC cases such as transplants, ECMO and tracheostomy. It shows which procedure and which secondary set the DRG, why every other secondary did or did not count, the DRG family with relative weights, and what a documented CC or MCC would change.
Is it really free?: Yes. A whole inpatient claim per check, the principal plus up to 24 secondaries and 25 procedures, with the complete grouper logic and no account required. The paid workspace carries the same codes into the conflict check, Medicare coverage policy and HCC scoring, keeps your work, and takes up to 50 of each.
Does it group surgical DRGs?: Yes. Enter the ICD-10-PCS codes, principal procedure first. A stay with an operating-room procedure groups surgically: the grouper ranks the procedures by CMS's surgical hierarchy for the principal diagnosis's MDC, and a procedure unrelated to that MDC lands the stay in DRGs 981–989, exactly as CMS assigns them.
Which CMS version does it use?: MS-DRG v44, effective for discharges from October 1, 2026, with the FY 2027 IPPS Table 5 relative weights. The grouping is our port of CMS's own Java grouper software, checked against it on tens of thousands of claims with no differences. Both versions are printed under every result.

What it does not do

Claim edits. The Medicare Code Editor’s edits (age and sex conflicts, questionable admissions, unacceptable principal diagnoses) are not run. Look a procedure up in ICD-10-PCS.
Payment. A relative weight is not a dollar amount. The hospital’s base rate, wage index and add-ons turn it into one, and none of those are here.
Your encoder. This is CMS’s grouper applied to the codes you typed. The coding itself is yours to get right, and the encoder on your claim has the whole record.

The MS-DRG reference lists every DRG with its weight and length of stay, and the free claim scrubber checks the same diagnoses for Excludes1 conflicts and sequencing errors before the claim goes out.