Egg Incubator Humidity Calculator
Pick your species and the day you're on. This tells you the relative humidity to hold right now, the temperature to run, when lockdown starts, and when to expect the hatch. Every figure comes from our egg incubator humidity guide.
Day 1 is the day you set the eggs.
What the calculator is actually telling you
The humidity number is a means to an end, not the goal. What you're really aiming for is about 13% egg weight loss from set to lockdown, or an air cell that has grown to roughly a third of the egg by the time lockdown starts. Humidity is just the dial you turn to get there.
That's why two hatchers in different climates can run very different RH and both do well — each is adjusting to land the same air cell. Use the range this gives you as a starting point, then candle around days 7, 14 and 18 and adjust. Air cell too small, drop the humidity. Growing too fast, raise it.
Reference chart — all species
| Species | Incubation (days) | Temp °F / °C | Setting RH | Lockdown RH |
|---|---|---|---|---|
| Chicken | 21 | 99.5 / 37.5 | 45–55% | 65–75% |
| Duck | 28 (Muscovy ~35) | 99.5 / 37.5 | 55–65% | 75–80% |
| Quail (Coturnix) | 17–18 | 99.5 / 37.5 | 45–55% | 65–70% |
| Turkey | 28 | 99.5 / 37.5 | 50–55% | 65–70% |
| Goose | 28–34 | 99.5 / 37.5 | 50–55% | 75–80% |
| Peacock | ~28 | 99.5 / 37.5 | 50–60% | ~70% |
| Guinea fowl | 26–28 | 99.5 / 37.5 | ~50% | 65–70% |
| Pheasant | 23–28 | 99.5 / 37.5 | ~50% | ~70% |
Lockdown begins about three days before the hatch date — day 18 for chickens, around day 25 for ducks and turkeys, later for geese and Muscovy ducks. Quail lock down around day 14–15.
Running drier on purpose
Dry incubation means running lower humidity through the setting phase — often 20–40% instead of the textbook 45–55% — then still raising it for lockdown. The reasoning is that plenty of homes and incubators sit humid enough that standard targets leave eggs too wet, giving small air cells and late losses.
Neither approach is universally right. In a humid climate, or with eggs that historically hatch wet, running drier often does better. In a dry house or a heated winter room, the standard band is the safer default. Candle, watch the air cell, and let that decide.
If your incubator can't hold its number
Most of the time a tabletop incubator plus the occasional top-up is all you need. Automation starts to matter when you're running several incubators, a homemade cabinet, or hatching in a dry house where a small unit spends all day fighting the room.
Calibrate the meter before you trust any of this
An uncalibrated hygrometer is one of the most common reasons a hatch fails — a meter reading 10% off will quietly ruin an otherwise perfect setup. Put the probe at egg height and check it against a known 75% RH with the salt test first. We walk through it in the salt-water calibration guide.
Hold the humidity around your incubator
Dial in the incubator first, then make sure the room isn't working against it. A cool-fog ultrasonic humidifier on a humidistat keeps ambient humidity steady so your incubator can hold its set point.
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More from House of Hydro: Egg incubator humidity guide · Mist maker sizing calculator · Build your own DIY humidifier · DIY tutorials & build guides.
General incubation figures reflect widely accepted ranges for hobby and small-flock hatching. Always follow your incubator's manual and adjust for your eggs, climate and altitude.