---
title: "Backoff & Jitter Calculator"
description: "Compute an exponential backoff schedule and see how full, equal, and decorrelated jitter spread the retries. Client-side, nothing is retried."
url: https://sade.dev/en/tools/backoff-calculator/
lang: en
author: "Muhammet Şafak"
published: 2026-06-17
updated: 2026-08-30
section: Tool
tags: ["retry","reliability"]
---

# Backoff & Jitter Calculator

> Compute an exponential backoff schedule and see how full, equal, and decorrelated jitter spread the retries. Client-side, nothing is retried.

Retries without jitter are how a transient blip becomes an outage. This works out the delay schedule for exponential backoff and shows how each jitter strategy spreads it across attempts. It only computes — it never retries anything.

## The formula

Exponential backoff is `delay = min(cap, base × factorⁿ⁻¹)` for attempt `n`:

- **base** — the first wait (e.g. 100 ms).
- **factor** — the growth per attempt (`2` doubles each time).
- **cap** — the ceiling, so the wait doesn't grow unbounded. Without a cap, `base 100ms × 2` reaches **~3.4 minutes** by attempt 12.

## Why jitter — the thundering herd

If a thousand clients back off on the **same** schedule, they retry in synchronized waves — the very spike that knocked the service over, repeated on a timer. Jitter desynchronizes them by randomizing the wait.

- **Full** — uniform in `[0, delay]`. Maximum spread; a client may retry very soon.
- **Equal** — uniform in `[delay/2, delay]`. Keeps a floor so nobody hammers instantly, but still spreads the herd.
- **Decorrelated** — the next wait is uniform in `[base, previous × 3]`, capped. It adapts to the last sleep and is a strong general default.
- **None** — the bare synchronized schedule. Fine for a single client; dangerous for a fleet.

## Reading the table

**Min/Max** is the range a given attempt's wait can fall into. For **None**, min equals max. The summary's *worst-case total wait* sums the maximum of every attempt — the longest a client could wait in total before giving up after N tries. Watch how **Full** and **Equal** pull the minimum down while the maximum — and so the worst-case total — stays exactly where **None** leaves it. **Decorrelated** widens the range instead: its floor sits at `base` while its ceiling climbs past **None**'s, so its worst-case total is larger, not smaller. What takes load off a recovering service is that spread across the range, not a shorter total.

A retry is also how the same message gets delivered twice, so the handler on the other end has to be idempotent: see the [BabelQueue idempotency spec](https://babelqueue.com/docs/spec/1.x/idempotency) and the runnable [`idempotency-payments` example](https://github.com/BabelQueue/babelqueue-examples/tree/main/idempotency-payments).

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