# Kidney Stone Passage Calculator

URL: https://speedycalculator.com/calculators/health/kidney-stone/
Last updated: 2026-10-30

> The kidney stone calculator estimates the chance that a ureteral stone will pass on its own from its size and location, and the typical time to passage, based on pooled study data.

## Inputs

- Stone size (largest diameter) (mm)
- Location

## Results

- Chance of passing spontaneously
- Typical time to pass

## Formula

```
Approximate spontaneous passage by size: ≤ 4 mm about 80%, 5–7 mm about 60%, 7–9 mm about 48%, > 9 mm about 25%
Distal ureteral stones pass more often than proximal ones
```

## Explanation

Most small kidney stones pass on their own within a few weeks, especially with pain relief and medical expulsive therapy (tamsulosin) for distal stones of 5–10 mm. Larger stones and those high in the ureter are more likely to need a procedure.

### How to use the Kidney Stone Passage Calculator

- **Stone size (largest diameter)**
- **Location**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter the stone's largest diameter and where it is. Seek urgent care for fever, uncontrolled pain or a single kidney.

### Inputs explained

FieldWhat to enterStone size (largest diameter)In mmLocationChoose one: Proximal ureter, Mid ureter, Distal ureter / UVJ

### Example values

How the main result changes when **Stone size** changes and everything else stays at the example values above:

Stone size (largest diameter) (mm)Chance of passing spontaneously (%)2.5873.75815656.25637.5551030
*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — Stone size (largest diameter): 5 mm; Location: Distal ureter / UVJ.

Results — **Chance of passing spontaneously = 65 %**; Typical time to pass = About 3 weeks.

## Key terms

- **UVJ**: Ureterovesical junction, where the ureter enters the bladder.
- **MET**: Medical expulsive therapy.

## FAQ

**What size kidney stone can pass naturally?**
Most stones under 5 mm pass; about half of 5–10 mm stones do.

**How long should I wait?**
Usually up to 4–6 weeks if pain is controlled and there is no infection.

**What helps a stone pass?**
Pain relief, staying hydrated and, for distal stones, tamsulosin if your doctor recommends it.


## Sources

- [Coll DM et al. Relationship of spontaneous passage of ureteral calculi to stone size and location. AJR, 2002](https://pubmed.ncbi.nlm.nih.gov/11756098/)
- [EAU Guidelines on urolithiasis](https://uroweb.org/guidelines/urolithiasis)