Tools and calculators

These tools help translate risk formats and support structured thinking. They are simplified and not clinical advice. For medical decisions, use validated tools with clinician input and local guidelines.

Safety note

If you have chest pain, stroke symptoms, severe bleeding, severe shortness of breath, or collapse: treat it as an emergency and call local emergency services. Do not use calculators to delay care.

General risk tools

Converter: percent ↔ 1 in N

Percent (%) 1 in N

“Chance × impact” comparator

Option A: chance (0–1) Option A: impact score (1–10) Option B: chance (0–1) Option B: impact score (1–10)

Impact score is subjective; use it to structure thinking, not to produce “true” numbers.

Medical risk calculators (educational)

These are commonly used clinical frameworks. The outputs here are informational; treatment decisions depend on context and clinician judgement.

CHA₂DS₂‑VASc (AF stroke risk)

Sex Age

Congestive heart failure / LV dysfunction Hypertension Diabetes Prior stroke / TIA / thromboembolism Vascular disease (MI, PAD, aortic plaque)

This tool does not recommend medication; it only summarizes the score.

eGFR (CKD‑EPI 2021, creatinine)

Age (years) Sex Creatinine unit Creatinine

Interpretation depends on persistence, urine findings, and clinical context.

MELD‑Na (liver disease severity)

Creatinine (mg/dL) Bilirubin (mg/dL) INR Sodium (mmol/L)

Used in transplant prioritization contexts; clinical care decisions require specialist input.

Wells score (Pulmonary embolism)

Clinical signs/symptoms of DVT PE is the most likely diagnosis (or equally likely) Heart rate > 100 Immobilization ≥3 days or surgery in previous 4 weeks Previous DVT/PE Hemoptysis Malignancy (on treatment, treated in last 6 months, or palliative)

Depression severity (PHQ‑9 total)

Enter PHQ‑9 total (0–27)

If you have thoughts of self-harm or suicide, seek urgent help via local emergency services or crisis support.

Surgery: validated tools (external)

For procedure-specific complication estimates, use validated calculators. Many systems (e.g., ACS NSQIP) are maintained externally and update over time.

ACS NSQIP Surgical Risk Calculator →

Common external calculators

Decision checklist (copy/paste)

1) What can go wrong?
2) How likely is it (per what unit)?
3) How bad is it (worst case + typical case)?
4) What reduces likelihood?
5) What reduces impact?
6) What is the best alternative?
7) What is the “regret test” if I choose A vs B?

Tools

General risk tools

Converter: percent ↔ 1 in N

“Chance × impact” comparator

Medical risk calculators (educational)

CHA₂DS₂‑VASc (AF stroke risk)

eGFR (CKD‑EPI 2021, creatinine)

MELD‑Na (liver disease severity)

Wells score (DVT)

Wells score (Pulmonary embolism)

Depression severity (PHQ‑9 total)

Surgery: validated tools (external)

Common external calculators

Decision checklist (copy/paste)