ConductScienceConductScience
ToolsConductScience tool
ZebrafishFree in-browser calculator

Zebrafish Embryo Staging Calculator.

Convert hours post-fertilization and incubation temperature to developmental stage using the Kimmel et al. (1995) staging series. Automatic temperature correction for 20–33°C.

Run calculator Request a Quote
PrivateData stays in your browser
LiveNo sign-up required
Validated2026-04-06
CitableMethods and citation included

Calculator

Results update in place

Try it out

Load example Embryo Staging data to see the full workflow

Configuration

20°C28.5°C33°C

When to use

  • Determining the developmental stage of embryos incubated at non-standard temperatures
  • Planning collection times for target stages (e.g., scheduling a 10-somite collection)
  • Estimating time until next developmental milestone for imaging or fixation
  • Converting between actual elapsed hours and standard hpf for publications

Do not use for

  • As a substitute for morphological confirmation — always verify stage under a microscope
  • For mutant or transgenic lines with known developmental delays — timing may differ
  • For temperatures outside 20–33°C — embryos are not viable in this range

Confirm stage morphologically

This calculator gives the expected stage based on time and temperature, but genetic background, egg quality, and culture conditions cause variation. Always confirm by examining somite count, pigmentation, or other morphological markers under the stereoscope.

Temperature shifts affect staging accuracy

If embryos were moved between different temperatures (e.g., overnight at 22°C then shifted to 28.5°C), the single-temperature calculation will not be accurate. In these cases, calculate the standard hpf accrued during each temperature interval separately and sum them.

Clutch-to-clutch variation

Even within a single cross at 28.5°C, developmental timing can vary by ±1–2 hours between clutches. For experiments requiring precise staging, collect embryos at a defined morphological landmark rather than relying solely on time.

Dark-rearing slows pigmentation, not development

Embryos raised in the dark develop at the same rate but show delayed melanophore pigmentation. Do not use pigmentation as a sole staging criterion for dark-reared embryos.

1

Method

Developmental rate is interpolated from the Kimmel temperature rate table (20–33°C). Actual elapsed hours are multiplied by the rate factor to yield standard hpf at 28.5°C. The standard hpf is then matched against the Kimmel staging series to identify the current period and stage. Time to next stage is calculated by dividing the remaining standard hours by the current rate factor.

2

Validated

Last validated 2026-04-06. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.

3

How to cite

How to Cite

ConductScience Zebrafish Embryo Staging Calculator (v1.0). ConductScience, Inc. 2026. Available at: https://conductscience.com/tools/zebrafish-embryo-staging-calculator

Kimmel CB, Ballard WW, Kimmel SR, Ullmann B, Schilling TF. Stages of embryonic development of the zebrafish. Dev Dyn. 1995;203(3):253–310.

Westerfield M. The Zebrafish Book, 5th Edition. University of Oregon Press. 2007.

Kimmel Staging Series Overview

The zebrafish staging series by Kimmel, Ballard, Kimmel, Ullmann, and Schilling (1995) defines the canonical stages of *Danio rerio* embryonic development from fertilization through early larval life. The series divides development into major periods:

  • Zygote (0–0.75 hpf): Single-cell stage with cytoplasmic streaming
  • Cleavage (0.75–2.25 hpf): Rapid synchronous cell divisions (2-cell through 64-cell)
  • Blastula (2.25–5.25 hpf): Cell cycles lengthen, MBT begins, epiboly initiates
  • Gastrula (5.25–10 hpf): Epiboly completes, germ layers form, embryonic axis established
  • Segmentation (10–24 hpf): Somites form (~2/hour), organogenesis begins
  • Pharyngula (24–48 hpf): Heartbeat, pigmentation, pharyngeal arches
  • Hatching (48–72 hpf): Embryos hatch from chorion, pectoral fins elongate
  • Larval (72+ hpf): Free-swimming, feeding, swim bladder inflation

All stage timings are defined at the standard incubation temperature of 28.5°C.

Temperature Effects on Zebrafish Development

Zebrafish are ectotherms and their developmental rate is directly governed by ambient temperature. The viable range for embryonic development is approximately 20–33°C, with the standard being 28.5°C.

Key effects of temperature manipulation: - Cooler (20–25°C): Development slows to 28–60% of standard rate. Useful for slowing development to collect stages at convenient times (e.g., overnight incubation at 22°C to obtain late-gastrula embryos in the morning). - Standard (28.5°C): Rate factor = 1.0. All published stage timings apply directly. - Warmer (29–33°C): Development accelerates to 105–132% of standard rate. Temperatures above 33°C cause developmental abnormalities and lethality.
Important: Temperature shifts should be gradual (≤2°C/hour) to avoid thermal shock. Prolonged incubation outside 25–30°C may affect morphology and gene expression patterns independently of staging.

Frequently asked

325
Free tools
1,200+
Institutions
100%
Client-side
0
Uploads required

Next steps

Equipment

Zebrafish Housing Systems

Recirculating rack systems with integrated filtration and temperature control for zebrafish facilities

Browse Equipment

Zebrafish Incubators

Temperature-controlled incubators for precise embryo staging and development

Browse Quote

Need help?

Get a quote on equipment or talk to the ConductScience team.

Request quote