How long to dehydrate tomatoes

Last reviewed July 2026.

Anywhere from 6 to 24 hours at 140°F — tomatoes are the wettest thing you'll put on a tray. Colorado State University Extension dries tomatoes at 140°F and gives a drying-time range of 6 to 24 hours, finished to crisp. That enormous spread isn't vagueness; it's water. A thin slice of a paste tomato in dry air finishes near the low end, while thick, juicy slicing tomatoes in a humid kitchen can run all day and into the next. The temperature is fixed by the record; the hours are set by how much juice has to leave.

Slice, and lay them cut side up

CSU cuts tomatoes into ½-inch-thick slices or ¾-inch sections. To make the skins slip, you can steam or dip in boiling water and then chill and peel first; an optional dip in a citric-acid solution (1 teaspoon per quart of water, about 10 minutes) preserves color. Lay slices in a single layer, and lay any halved tomatoes cut side up so the juice doesn't run off the tray. The doneness test is the same as for other vegetables: dry all the way to crisp, not leathery, for shelf storage.

Cherry tomatoes, and "what temp"

Cherry and grape tomatoes are searched constantly, usually with what temp attached. Same 140°F. The trick is the skin: halve each cherry tomato and lay the halves cut side up so moisture can escape the cut face — dried whole, the waxy skin traps water and the tomato can take nearly forever or never finish evenly. Halved, they dry on the same 140°F/crisp target as slices, just faster because the pieces are small.

Tomato powder

Powder is not a different process — it's a longer one. Dry the slices fully to crisp and brittle, with no flex and no cool moisture left, then grind the finished pieces in a spice grinder or blender. The single most important thing for powder is that the tomatoes are bone-dry before grinding: any residual moisture cakes the powder and shortens its shelf life. Store it airtight, and keep it sealed until use — tomato powder pulls moisture from the air fast and clumps.

Sun-dried tomatoes

"Sun-dried" in a dehydrator is the same 140°F drying — the name is about the style, not a special setting. Dry to a pliable, leathery state if you plan to pack them in oil for near-term use, or all the way to crisp for dry shelf storage. If you oil-pack them, that's a refrigerated, use-soon product; the fully dried, jarred version is the one that keeps at room temperature. When in doubt, dry further — a too-wet "sun-dried" tomato in oil is a spoilage risk, not a shortcut.

In an air fryer, or in an oven

A Ninja or other air fryer on a dehydrate setting can dry a thin single layer of tomato or halved cherry tomatoes, but the small basket and strong fan mean small batches and close watching — a high-airflow chamber crisps the thin edges well ahead of the wet centers. An oven runs the same 140°F logic with the door propped for airflow, and because a home oven moves less air than a dehydrator it tends to run at the long end of the 6–24 hour range. In every case the temperature is the record's 140°F and the finish is crisp; only the airflow, and so the hours, differ.

Sources — read them yourself

• Colorado State University Extension — Drying Vegetables (tomatoes: 140°F, 6–24 h, ½″ slices / ¾″ sections, citric-acid dip, crisp)
• University of Minnesota Extension — How to dry tomatoes at home (140°F, cut side up, cherry halved)
• NCHFP — Drying foods at home (vegetable drying temperatures and doneness)

Related: how long to dehydrate apples · how long to dehydrate zucchini · why produce dries at ~135–140°F, not 165°F.

Dehydrator Score indexes published specs and marketing claims against the USDA/NCHFP record, with attribution — we test nothing and give no safety advice. For drying guidance use NCHFP or your extension office. If a source changes, the page changes — the record wins.