Sourdough Internal Temperature Guide

The most reliable way to know if your sourdough is fully baked is to measure its internal temperature with a probe thermometer. Visual cues — crust colour, hollow sound when tapped — are useful but imprecise. Internal temperature removes the guesswork.

What Temperature Should Sourdough Be When Done?

A fully baked sourdough loaf should reach an internal temperature of 94–98°C (202–208°F). Most bakers target 96°C (205°F) as a reliable endpoint.

At this temperature:

• Starch has fully gelatinised (no raw or gummy crumb)
• The crumb structure has set and will hold when sliced
• Residual moisture has been driven out of the centre
• The Maillard reaction and caramelisation have developed the crust

Below 93°C (200°F), the crumb may be gummy or underbaked in the centre, even if the crust looks perfect. Above 99°C (210°F), the loaf is drying out rather than baking — not harmful, but unnecessary.

Where to Insert the Thermometer

Insert from the side or the base, not from the top through the crust.

The correct technique:

1. Use a thin instant-read probe thermometer

   A Thermapen or similar slim probe works best — thick probes leave visible holes.

2. Insert through the side of the loaf

   Aim for the geometric centre, entering at mid-height on the side.

3. Push to the centre

   The centre is the coldest point — that’s the reading you want.

4. Wait 5–10 seconds

   Let the reading stabilise before pulling the probe out.

Why not from the top? Inserting through the scored top crust means the probe travels through already-hot outer crumb before reaching the centre, and the entry hole may cause steam loss and partial collapse of the crumb structure. Side insertion gives a cleaner, more accurate reading.

Why the centre? The centre of the loaf is always the last part to reach full temperature. If you measure near the edge, you’ll get a reading 10–15°C higher than the true centre — and a potentially underbaked core.

Crust Temperature vs Crumb Temperature

The crust and crumb cook very differently and reach very different temperatures.

Crust temperature during baking: 150–200°C (300–390°F). The crust is a dry, high-temperature zone where Maillard browning and caramelisation reactions occur. This is why sourdough crust is hard, brown, and flavourful.

Crumb temperature at doneness: 94–98°C (202–208°F). The crumb stays below 100°C while moisture remains. The water inside the crumb acts as a heat sink — it can’t exceed boiling point until it evaporates. This is why internal temperature plateaus around 96°C in the final minutes of baking even as the oven temperature is 230°C.

This difference explains why a loaf can look dark and done on the outside while still being underbaked in the centre. The crust temperature gives you no reliable information about the crumb.

What Causes a Gummy Crumb?

A gummy, wet, or dense crumb is usually one of three things:

1. Underbaked (most common): Internal temperature below 94°C. The starch hasn’t fully gelatinised and the crumb hasn’t set. Fix: bake longer, even if the crust looks done. Remove the Dutch oven lid and continue baking until the probe reads 96°C.

2. Overproofed dough: The gluten structure collapsed during over-fermentation and the crumb can’t hold its structure regardless of baking temperature. The gumminess in this case is structural, not moisture-related.

3. Sliced too soon: Even a fully baked loaf will have a gummy or wet crumb if sliced while still hot. The crumb needs to cool and the steam to redistribute for at least 1–2 hours before slicing. Ideally, wait 3–4 hours.

How Oven Temperature Affects Internal Temperature

A hotter oven browns the crust faster but doesn’t necessarily cook the crumb faster — moisture is still the limiting factor. Cranking the oven to 260°C instead of 230°C will give you a darker crust in less time, but the crumb will still take similar time to reach 96°C.

What oven temperature does affect is the crust thickness and crumb texture. Higher temperatures produce a thicker, cracklier crust. Lower temperatures (220°C and below) can produce a softer crust and a more evenly cooked crumb.

Most sourdough bakers use 230–250°C (446–482°F) with a Dutch oven:

• Lid on for 20 minutes (steam phase, oven spring)
• Lid off for 20–25 minutes (browning phase)
• Check internal temperature at 35–40 minutes total

Thermometer Types

Instant-read probe thermometers (Thermapen, ThermoPop) are ideal — fast, accurate, thin probe. A quality instant-read is one of the most useful tools in a bread baker’s kit.

Leave-in probe thermometers can be useful for monitoring during baking without opening the oven, though the entry hole in the dough can affect crust formation at that spot.

Infrared (laser) thermometers measure surface temperature only — completely useless for checking internal crumb temperature. Don’t use these for bread doneness.

Baking at Altitude

Water boils at lower temperatures at high altitude — around 93°C at 2000m elevation, and lower still at higher altitudes. This means the internal temperature of bread at full doneness is lower at altitude than at sea level.

If you bake at significant altitude (above 1500m), target an internal temperature of 92–95°C (197–203°F) rather than 96°C. Your crust will develop and set at a lower crumb temperature because the boiling point of water is lower.

Baking Without a Dutch Oven

Without a Dutch oven, it’s harder to trap steam during the first phase of baking, which affects oven spring. But internal temperature targets remain the same: 94–98°C.

Common alternatives for home ovens:

• Place a roasting pan of boiling water on the bottom rack during the first 20 minutes
• Cover the loaf loosely with an inverted roasting pan for the first 20 minutes
• Bake on a preheated baking stone

Internal temperature is, if anything, more useful when baking without a Dutch oven — because crust colour is less reliable as a doneness indicator when steam management is inconsistent.

FAQs

What if my loaf reaches 96°C but the crust isn’t dark enough? Remove the loaf from the Dutch oven and place it directly on the oven rack for 5–10 more minutes at the same temperature. This crisps and darkens the crust without overcooking the crumb.

My sourdough reads 96°C but the crumb is still gummy. Why? The most likely cause is slicing too soon. Let the loaf cool for at least 2 hours before cutting. If it’s still gummy after cooling, the issue may be overproofing (gluten breakdown) rather than underbaking.

Should I measure temperature through the score or the side? The side or base. Measuring through a score mark works but risks affecting crumb structure and gives a less accurate reading because the probe may travel through an air pocket. The side gives the cleanest path to the centre.

My oven runs hot — should I adjust my target temperature? No — the target internal temperature of the bread doesn’t change based on oven temperature. 96°C crumb temperature means 96°C regardless of your oven. What changes is how quickly the crust browns, so you may need to lower your oven setting or tent with foil to prevent the crust burning before the crumb is done.

Can I use the same thermometer for dough temperature and baked bread? Yes. A good instant-read probe thermometer is equally useful for measuring dough temperature during bulk fermentation (target: 24–26°C) and baked bread doneness (target: 96°C). It’s one of the best all-purpose investments for a sourdough baker.

Is there a temperature test for knowing when to bake (proofing)? Not a reliable one — the dough doesn’t hit a specific temperature that indicates readiness. For proofing readiness, use the poke test (gently poke the shaped, floured dough — it should spring back slowly, about halfway) and visual rise. For fermentation timing during bulk, use the bulk fermentation calculator.