Plain tomato sauce, water-bath canned
Unseasoned tomato sauce boiled down from juice — thin for soups, thick for pasta — with every flavour decision left for the day you open it.
Makes
About 7 × 1 L (quart) jars of thin sauce from 16 kg (35 lb) of tomatoes, or of thick sauce from 21 kg (46 lb); for 9 × 500 ml (pint) jars use 9.5 kg (21 lb) thin or 12.7 kg (28 lb) thick
Active time
2 hours
Total
4–5 hours, plus 12–24 hours cooling
Photo naturalflow on Flickr · CC BY-SA 2.0
Before you start
What keeps this jar safe
- Acid in every jar, measured, before the sauce goes in. Boiling the sauce down concentrates the tomato but does not make it acidic enough on its own.
- This is plain sauce: no onion, garlic, peppers, herbs, oil or thickeners. Seasoned ‘spaghetti sauce’ is a low-acid mixture with its own tested pressure-canning recipe.
- Headspace is a tight 6 mm (¼ inch) for sauce, less than for crushed tomatoes — measure it.
- Keep the sauce at a boil when you fill the jars; a cooled, thick sauce heats slowly in the canner.
This follows NCHFP: Standard Tomato Sauce. Quantities, acid and times are theirs; do not scale the vegetables without scaling everything, and do not change the vinegar, lemon juice or processing time.
Ingredients
- 16 kg (35 lb) ripe tomatoes for thin sauce, or 21 kg (46 lb) for thick sauce — paste tomatoes cook down fastest
- Bottled lemon juice: 2 tablespoons (30 ml) per 1 L jar, 1 tablespoon (15 ml) per 500 ml jar — or citric acid, ½ teaspoon per 1 L jar, ¼ teaspoon per 500 ml jar
- Salt, optional: 1 teaspoon (5 ml) per 1 L jar
Processing
- Jars
- 500 ml (pint) · 1 L (quart) in brackets
- Headspace
- 6 mm (¼ inch)
- Time at 0–300 m (0–1,000 ft)
- 35 min
- Higher up
- 1 L jars: 40 min. For both sizes add 5 min at 300–900 m (1,001–3,000 ft), 10 min at 900–1,800 m (3,001–6,000 ft), 15 min above 1,800 m (6,000 ft).
Method
- 1
Wash the tomatoes (a child can do this), cut out stems and any bruised or dark patches. Quarter about 500 g into a large pot and heat hard while crushing them; as it boils, keep adding and crushing quarters so the pot never stops boiling. Simmer 5 minutes once everything is in.
- 2
Press the hot pulp through a food mill or sieve to take out skins and seeds. Pour the juice into the widest pot you own — a wide pot evaporates faster.
- 3
Simmer, stirring now and then so it does not catch, until the volume has dropped by a third for thin sauce or by half for thick sauce. Mark the starting level on a wooden spoon handle so you can tell. This takes an hour or more.
- 4
Set the washed jars to heat in the canner and wash the lids. Put the lemon juice (or citric acid) into each hot jar, plus salt if you like.
- 5
Fill the jars with boiling-hot sauce, leaving only 6 mm (¼ inch) headspace. Free any bubbles with a chopstick, wipe the rims, centre the lids and screw the bands on fingertip-tight.
- 6
Lower into the canner with at least 5 cm (2 inches) of water over the lids, bring to a full rolling boil and time it: 500 ml jars 35 minutes, 1 L jars 40 minutes at 0–300 m.
- 7
Turn off the heat, uncover, wait 5 minutes, lift the jars onto a towel and leave 12–24 hours. Check the seals; refrigerate any that failed and use within a week.
Keeps: 12–18 months in a cool dark cupboard. Refrigerate after opening and use within 5–7 days.
Variations: Thin sauce (reduced by a third) is the better all-rounder — thicken it in the pan in winter. If a smooth texture matters less, make the crushed-tomatoes recipe instead and use its headspace and times (1.25 cm; 500 ml 35 min, 1 L 45 min).
Tested source: NCHFP: Standard Tomato Sauce. Checked October 2026. If a jar did not seal, refrigerate it and use it within a few days. Never taste anything from a jar that is bulging, leaking, spurting or smells wrong — when in doubt, throw it out without tasting.
The crop
Tomatoes: when to pick, how to store, what else to make →
Tomatoes are the home canner’s classic, but they sit right on the acidity line: every tested canned-tomato recipe adds bottled lemon juice or citric acid to each jar, and that is not optional whether you water-bath or pressure can. Whole tomatoes freeze well with no blanching — the skins slip off under the tap as they thaw — which is the fastest way to deal with a glut on a weeknight. Cherry and paste tomatoes dry beautifully. What does not work is a sauce you have thickened with flour or loaded with extra peppers, onions and oil to taste: the added low-acid vegetables change the safety of the recipe, so follow a tested salsa or sauce recipe exactly. Green tomatoes are more acidic than ripe ones and can be canned by the same recipes, with the same added acid.
More for tomatoes
- Water-bath canning
Crushed tomatoes, water-bath canned
The plainest, most useful jar in the pantry: tomatoes and nothing else, ready for any sauce in February.
About 7 × 1 L (quart) jars from 10 kg (22 lb) of tomatoes; 6.4 kg (14 lb) fills 9 × 500 ml (pint) jars · 1½ hours active
The recipe → - Water-bath canning
Whole or halved tomatoes in juice, water-bath canned
Whole peeled tomatoes under their own juice — the jar you open for a winter stew when you want pieces, not purée.
7 × 1 L (quart) jars from 9.5 kg (21 lb) of tomatoes, plus extra tomatoes for the juice; 5.9 kg (13 lb) fills 9 × 500 ml (pint) jars · 1½ hours active
The recipe → - Water-bath canning
Choice salsa, water-bath canned
The tested salsa that lets you choose the peppers and onions — mild or fierce — as long as the measured cups and the lemon juice stay exactly as written.
About 6 × 500 ml (pint) jars · 1¼ hours active
The recipe →