Audited —·Last updated 31 Jul 2026·5 citations·Tier 2·0 uses

Oil to Butter Converter

Swap oil for butter or butter for oil on USDA composition data, with the fat matched exactly and the water the swap removes reported beside it.

Oil to Butter Converter

Which way?
How much of the fat the recipe calls for, in the unit chosen below.
Measured in
Match on
Use this much
184.1197
Grams of the replacement fat. On the fat-equivalent basis this is the quantity that carries exactly the same fat as the original, which for butter to oil means multiplying by 0.8111 — USDA's measured milkfat fraction for salted butter.
In cups
0.8446
In tablespoons
13.5134 tbsp
In teaspoons
40.5401 tsp
The recipe's fat
227 g
Fat in the original
184.1197 g
Fat in the substitute
184.1197 g
Change in fat
0 g
Change in water
-36.7059 g
Ratio by weight
0.8111
Ratio by volume
0.8446
Basis note
Basis: matched on fat, from USDA composition (butter 81.11% fat, oil 100%). 227 g of butter becomes 184.12 g of oil — a ratio of 0.8111 by weight and 0.8446 by volume. For comparison, weightForWeight would give 227 g (1.04 cups), 42.88 g more fat; traditionalRule would give 163.5 g (0.75 cups), 20.62 g less fat.
Summary
Replace 227 g of butter with 184.12 g of oil — 0.84 cups, or 13.51 tbsp. The swap removes about 36.71 g of water and changes the fat by 0 g.

Background.

Swapping oil for butter is not a unit conversion, and treating it as one is where most kitchen advice goes wrong. Butter and oil are different substances. USDA FoodData Central measures salted butter at 81.11 percent fat and 16.17 percent water; a liquid cooking oil is essentially 100 percent fat and no water at all. So a gram of oil delivers about a quarter more fat than a gram of butter, and every gram of butter you take out of a recipe takes about a sixth of a gram of water with it. This calculator handles both consequences, in both directions, and tells you which is which.

The default basis matches the fat, because that is the only basis that can be derived from primary data. A cup of butter is 227 grams on USDA's own portion table, so it carries 227 times 0.8111 equals 184.12 grams of fat. Oil is all fat, so 184.12 grams of oil delivers exactly the same — and because oil weighs 218 grams to the cup rather than butter's 227, that comes out at 0.84 cups, or about 13.5 tablespoons. The change in fat on this basis is exactly zero, which is not an approximation but an identity the test suite asserts.

The page also offers the ratio almost everyone has been told: three quarters of a cup of oil per cup of butter. It is worth being direct about that figure's status. No standards body, no government agency, no manufacturer and no peer-reviewed source publishes it — it is a kitchen convention, repeated across recipe sites, and this page labels it as one rather than dressing it up. It is also 11.2 percent short: three quarters of a cup of oil is 163.5 grams and carries 163.5 grams of fat against the 184.12 in a cup of butter. Whether that matters depends on what you are making. In a quick loaf it is invisible; in a cake where the fat is doing structural work it is not. The basis note reports all three figures side by side whichever one you pick, so the cost of the convention is on the screen rather than buried.

The water is the part that no conversion chart mentions. Replacing a cup of butter with oil removes about 36.7 grams of water from the recipe, which is a meaningful fraction of the liquid in a cake batter. This page computes that figure from USDA composition and reports it — and then stops, because no authority consulted publishes a rule for replacing it. Some bakers add a little milk or water back; others rely on oil's own behaviour to compensate. The page will not invent a recommendation it cannot source, so it gives you the number and leaves the decision where it belongs.

One thing arithmetic cannot fix belongs here rather than in an FAQ, because it decides whether you should make the swap at all: butter is solid at room temperature and oil is not. Creaming butter with sugar whips air into a batter, and that aeration is a leavening mechanism in its own right. Cold solid butter is what makes shortcrust short and what laminates puff pastry into layers. Oil cannot do either. Cakes, muffins, quick breads and brownies substitute happily and often come out moister. Shortbread, pie crust, croissants, biscuits and anything creamed will not work, no matter how exactly the fat is matched. The page's fat figures are correct and are not the whole story, which is the honest thing to say beside them.

What is oil to butter converter?

An oil-for-butter substitution replaces one cooking fat with another of different composition. The two figures that govern it are the fat fraction and the water fraction, and USDA FoodData Central publishes both: salted butter (entry 173410) at 81.11 grams of total lipid and 16.17 grams of water per 100 grams, canola oil (entry 172336) at 100 grams of fat and no water. Butter's remaining 2.72 percent is milk solids-not-fat plus salt.

That gives three defensible bases, and the page ships all three rather than picking silently. Matching the fat multiplies by 0.8111 going from butter to oil, and divides by it coming back. Matching the weight is a one-for-one swap that overshoots the fat by about 23 percent when oil replaces butter. The traditional three-quarters-of-a-cup convention is defined on volume and undershoots the fat by 11.2 percent.

Volume figures need each fat's own density. USDA's cup portions give butter at 227 grams and oil at 218, which against NIST's exact cup of 236.5882365 millilitres works out at 0.9594 and 0.9214 grams per millilitre respectively.

The range of validity is any recipe where the fat's only job is to be fat. It is exact arithmetic on published composition figures. What it does not cover: the aeration that creaming solid butter provides, the layering that cold solid fat provides in pastry, butter's browning and flavour contribution from its milk solids, unsalted butter's different water content, clarified butter and ghee, and oils other than canola — all liquid oils are near enough 100 percent fat, but their cup weights differ by a percent or two.

How to use this calculator.

  1. Choose the direction. Butter to oil is the common case; oil to butter is the reverse and it adds water to the recipe rather than removing it.
  2. Enter the amount the recipe calls for and pick its unit. Sticks is available for butter only — the calculator refuses it for oil rather than inventing an oil stick.
  3. Leave the basis on fat-equivalent unless you have a reason not to. It is the only one of the three derivable from primary composition data, and it is the one that makes the change in fat exactly zero.
  4. Read the headline gram figure, then the cup and tablespoon equivalents beneath it. Those use each fat's own density, so the volume ratio and the weight ratio are deliberately different numbers.
  5. Look at the change in water. Replacing butter removes it; replacing oil adds it. The page reports the amount and does not tell you what to do about it, because no source it could cite publishes a rule.
  6. Read the basis note before you commit to the traditional three-quarter-cup rule. It shows what that convention costs in fat against the fat-equivalent answer, for your specific quantity.
  7. Ask whether the recipe creams the butter or relies on it being cold and solid. If it does — shortbread, pie crust, laminated pastry, anything beaten with sugar until pale — no substitution ratio will save it, and the right answer is to use butter.

The formula.

g_sub = g_orig × fat_orig ⁄ fat_sub ; Δwater = g_sub·w_sub − g_orig·w_orig
g_orig · the recipe's fat, in gramsg_sub · the replacement fat, in gramsfat_orig, fat_sub · fat fractions — butter 0.8111, oil 1.0000 (USDA)w_orig, w_sub · water fractions — butter 0.1617, oil 0 (USDA)cup · butter 227 g, oil 218 g (USDA portions)tbsp · cup ⁄ 16 ; tsp · cup ⁄ 48 (NIST SP 811)traditional basis · 0.75 cups of oil per cup of butter, by volume

Start by turning the entered amount into grams using the density of the fat the recipe names, not the fat you are switching to. A cup of butter is 227 g and a cup of oil is 218 g, both from USDA's portion tables, and tablespoons and teaspoons are derived from the cup using NIST's exact identities that a cup is 16 tablespoons and 48 teaspoons.

Then apply the basis. On fat-equivalent, the substitute must deliver the same grams of fat, so its weight is the original weight times the original's fat fraction divided by the substitute's. Butter to oil is 0.8111 divided by 1, so multiply by 0.8111. Oil to butter is 1 divided by 0.8111, so divide. Because nothing is rounded between those two steps, the change in fat comes back as exactly zero rather than as a rounding residue, and the test suite asserts that at five different input sizes in both directions.

On weight-for-weight the substitute weight equals the original weight, and the fat moves: a cup of butter's 227 g becomes 227 g of oil carrying 227 g of fat against the butter's 184.12, which is 42.88 g more.

On the traditional basis the rule is stated in volume, so the arithmetic is done in volume: convert to cups, multiply by 0.75 going from butter to oil or divide by 0.75 coming back, then convert to grams using the substitute's cup weight. That makes the volume ratio exactly 0.75 while the weight ratio comes out at 0.7203, because the two fats have different densities. A cup of butter becomes 0.75 cups, 163.5 g, of oil — 20.62 g less fat, 11.199 percent short.

The water is a separate subtraction: the substitute's water minus the original's. Oil has none, so replacing a cup of butter loses the whole 227 times 0.1617 equals 36.71 g. Going the other way adds water in proportion to the butter used.

Why the cup is the density anchor rather than the tablespoon. USDA publishes both for each fat, and for oil they disagree: 16 tablespoons of 14 g is 224 g against a published cup of 218 g, a 2.75 percent gap. NIST's exact cup of 236.5882365 mL settles it. The cup implies 218 divided by 236.5882365 equals 0.9214 g/mL, which is the right order for an edible oil. The tablespoon implies 14 divided by 14.7868 equals 0.9468 g/mL, which is higher than any edible oil. So the cup is the physically consistent figure, every spoon measure is derived from it, and the discrepancy is documented instead of absorbed. The same test on butter gives 0.9594 from the cup and 0.9603 from the tablespoon — 0.09 percent apart, immaterial — and the cup is used there too for symmetry.

There is one more density disagreement worth naming, because it is large. King Arthur's ingredient chart gives vegetable oil at 198 g per cup against USDA's 218 — a ten percent difference that would move every volume figure on this page by ten percent. The same NIST test resolves it: 198 g in a 236.5882365 mL cup is 0.837 g/mL, which is lighter than any edible oil. USDA's figure is used, and the effect of the choice is stated: a cup of butter maps to 0.8446 cups of oil here and would map to 0.9299 cups on King Arthur's density, a difference of about 1.4 tablespoons.

Rounding stage. Nothing is rounded at an intermediate step. Every quantity is carried in arbitrary-precision decimal arithmetic and rounded exactly once, at the point the result leaves the calculator, to ten decimal places, with negative zero normalised so that an exact cancellation reads as 0.

Classification stage. This page classifies nothing into bands. Every numeric output is a mass, a volume or a ratio, and the two text outputs state figures and their provenance without attaching a verdict word to any of them, so no band edge exists that could be decided from a rounded value. What is tested instead are two identities: the fat difference must be exactly zero on the fat-equivalent basis, and converting one way and then back must return the starting grams to ten decimal places on all three bases.

A worked example.

Example

A baker has a cake recipe calling for one cup of butter and wants to use oil. On USDA's portion table a cup of butter is 227 g, so originalGrams reads 227. At USDA's measured milkfat fraction of 81.11 percent, fatInOriginalG is 227 x 0.8111 = 184.1197 g. Oil is 100 percent fat, so to deliver the same fat it needs to weigh the same as that fat figure: substituteGrams is 184.1197 g. Because oil weighs 218 g to the cup rather than butter's 227, substituteCups is 184.1197 / 218 = 0.8445857798 cups, which is substituteTablespoons = 13.5133724771 tbsp — call it thirteen and a half tablespoons. fatInSubstituteG is 184.1197 g and fatDifferenceG is therefore exactly 0, which is the whole point of this basis and is asserted as a test rather than assumed. The ratios differ, deliberately: substitutionRatioByWeight is 0.8111 — exactly the milkfat fraction — while substitutionRatioByVolume is 0.8445857798, because the two fats have different densities. The figure no conversion chart mentions is waterChangeG, which reads -36.7059 g: oil carries no water, so the swap removes the whole 227 x 0.1617 grams that the butter was contributing. That is a meaningful fraction of the liquid in a cake batter, and the page reports it without telling you to add it back, because no authority it could cite publishes such a rule. For contrast, the basis note computes the other two options on the same input. Weight-for-weight would use 227 g of oil, 1.04 cups, carrying 42.88 g more fat than the recipe had. The traditional three-quarter-cup rule would use exactly 0.75 cups, 163.5 g, carrying 20.62 g less fat — 11.199 percent short of what a cup of butter delivers. All three are on the screen at once, so the convention's cost is visible rather than implied.

amount1
substitution BasisfatEquivalent
amount Unitcups
directionbutterToOil

Frequently asked questions.

Is the three-quarter-cup rule wrong?
It is not sourced, and it is 11.2 percent short of fat-equivalent. Those are different claims from "wrong", and the page keeps them separate. No standards body, government agency, manufacturer or peer-reviewed source publishes "use 3/4 cup of oil per cup of butter" — it is a kitchen convention that recipe sites repeat, and this calculator labels it as one instead of presenting it as a figure with provenance. What can be computed is what it costs: 0.75 cups of oil is 163.5 g and carries 163.5 g of fat, against the 184.12 g in a cup of butter. For a quick bread or a muffin that shortfall is invisible, and oil's own moistening effect may more than compensate. For a cake where the fat is doing structural work it is a real reduction. The fat-equivalent answer, 0.84 cups, is the one derivable from primary composition data, which is why it is the default.
Should I add liquid back to replace the water in the butter?
The page gives you the number and deliberately declines to give you a rule, because there is no rule it can cite. Replacing a cup of butter with oil removes about 36.7 g of water from the recipe — that is USDA's measured 16.17 percent water content of salted butter, applied to a 227 g cup — and 36.7 g is roughly two and a half tablespoons, which is a meaningful fraction of the liquid in a cake batter. Some bakers add a little milk or water back; others do not, on the grounds that oil coats flour more thoroughly than solid butter and produces a batter that reads as wetter at the same nominal liquid. No standards body, manufacturer or peer-reviewed source consulted for this page publishes guidance either way, so none is invented. The honest output is the water figure and the reasoning, with the decision left with you.
When should I not substitute oil for butter?
Whenever the recipe needs the butter to be solid, and no ratio can change that. Two mechanisms depend on it. Creaming — beating butter with sugar until pale and fluffy — whips air into the fat, and that trapped air is a leavening mechanism on its own; oil cannot hold it, so a creamed cake made with oil rises less and has a different crumb. Lamination and shortening depend on discrete pieces of cold solid fat separating layers of dough or coating flour to block gluten development; that is what makes puff pastry layer and shortcrust short. Oil disperses instead. So: cakes, muffins, quick breads, brownies and most loaf cakes substitute well and often come out moister. Shortbread, pie and tart crusts, croissants, puff pastry, scones, biscuits and any creamed batter will not, however exactly the fat is matched. That belongs in the intro of this page, not in a collapsed FAQ, because it decides whether to use the calculator at all.
Why is the volume ratio not the same as the weight ratio?
Because butter and oil have different densities, so equal weights are not equal volumes. On the fat-equivalent basis the weight ratio going from butter to oil is exactly 0.8111 — USDA's milkfat fraction — but the volume ratio is 0.8446, because oil weighs 218 g to the cup against butter's 227. That is a four-percentage-point difference and it is not a rounding artefact. The traditional rule shows the same thing from the other side: it is defined on volume, so its volume ratio is exactly 0.75 while its weight ratio comes out at 0.7203. Whenever a substitution rule is quoted, it is worth knowing which of the two it means. This page reports both, so a rule you find elsewhere can be identified as one or the other and compared properly.
Does it matter which oil I use?
Barely for the fat and a little for the volume. Every liquid edible oil is essentially 100 percent fat with no water, so the weight arithmetic is close to oil-independent — canola, sunflower, corn, light olive and grapeseed all behave the same way in the fat-equivalent calculation. What does vary is the cup weight, because densities differ by a percent or two, so the volume figures shift slightly with the oil. The page uses USDA's canola entry at 218 g per cup. Flavour is a separate question the arithmetic says nothing about: extra-virgin olive oil brings a pronounced taste that suits some savoury bakes and overwhelms most sweet ones, coconut oil is solid below about 24 °C and therefore behaves more like butter than like oil, and butter's own flavour comes largely from milk solids that no oil contains at all.
Which oil density is right — USDA's 218 g per cup or King Arthur's 198?
USDA's, and the test that settles it does not depend on trusting either publisher. NIST fixes the US cup at exactly 236.5882365 millilitres. USDA's 218 g per cup therefore implies a density of 0.9214 g/mL, and King Arthur's 198 g implies 0.837 g/mL. Edible vegetable oils sit a little below water, in the low 0.9s — which is why oil floats on water but only just. A density of 0.837 would make oil dramatically lighter than any edible oil actually is, so that is the figure that fails the physical check. The disagreement is not academic: it moves every volume figure on this page by about ten percent. A cup of butter maps to 0.8446 cups of oil on USDA's density and would map to 0.9299 cups on King Arthur's, a difference of roughly 1.4 tablespoons per cup of butter. The choice is recorded rather than made silently.
Is the 81.11 percent fat figure reliable?
It is a measured mean rather than a specification, and it is confirmed from outside USDA. USDA's figure for salted butter rests on 580 data points, and 81.11 percent clears both the 80 percent statutory floor in 21 U.S.C. 321a — "not less than 80 per centum by weight of milk fat" — and the identical 80 percent minimum in Codex Alimentarius CXS 279-1971, the international standard. So three independent authorities agree that butter is at least 80 percent fat, and USDA's measurement puts the average just above it. The page reports the statutory floor alongside the measured mean so you can see the range. The water figure is less settled: USDA measures 16.17 percent from seven samples spanning 15.8 to 16.61, while Codex caps butter water at 16 percent — so the measured mean sits marginally above the international ceiling. The page says so rather than choosing, and treats water as an average rather than a limit.

References& sources.

  1. [1]U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, SR Legacy entry FDC ID 173410, "Butter, salted"; retrieved 30 July 2026 through the FoodData Central REST API endpoint /v1/food/173410. The source of butter's composition and density on this page: total lipid (fat) 81.11 g per 100 g from 580 data points; water 16.17 g per 100 g from 7 analytical samples spanning 15.8 to 16.61 g; portions 1 cup = 227 g, 1 stick = 113 g, 1 tablespoon = 14.2 g, 1 pat = 5 g. Independence: primary. Access: open.
  2. [2]U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, SR Legacy entry FDC ID 172336, "Oil, canola" (low erucic acid rapeseed oil); retrieved 30 July 2026 through the FoodData Central REST API endpoint /v1/food/172336. The source of oil's composition and density: total lipid 100 g per 100 g from 8 data points, water 0 g per 100 g, and portions 1 cup = 218 g, 1 tablespoon = 14 g, 1 teaspoon = 4.5 g. The cup is used as this page's density anchor and the separately published tablespoon is documented as inconsistent with it (16 x 14 = 224 g against a 218 g cup). Independence: primary. Access: open.
  3. [3]United States Code, Title 21, Section 321a — "Butter" defined (enacted 4 March 1923, 42 Stat. 1500); retrieved 30 July 2026 from the Cornell Legal Information Institute's reproduction of the US Code. Quoted for the statutory floor reported beside USDA's measured milkfat mean: butter is the food "made exclusively from milk or cream, or both, with or without common salt, and with or without additional coloring matter, and containing not less than 80 per centum by weight of milk fat, all tolerances having been allowed for." Independence: primary. Access: open.
  4. [4]National Institute of Standards and Technology. NIST Special Publication 811, 2008 edition — Guide for the Use of the International System of Units (SI). Table B.6 US customary capacity: cup exactly 236.5882365 mL, tablespoon 14.78676478125 mL, teaspoon 4.92892159375 mL, hence the exact identities 1 cup = 16 tablespoons = 48 teaspoons that this page uses to derive every spoon figure from the cup; Table B.8 avoirdupois mass: ounce exactly 28.349523125 g. The exact cup is also the instrument that resolves the two density conflicts documented on the page, by converting each published gram-per-cup figure into an implied g/mL. Independence: primary. Access: open.
  5. [5]King Arthur Baking Company. Ingredient Weight Chart, current revision; retrieved 30 July 2026. Cited for the figure this page records as a conflict and does not use: "Vegetable Oil — 1 cup: 7 ounces / 198 grams", against USDA's 218 g. The chart's butter entry, "8 tablespoons (1/2 cup): 4 ounces / 113 grams", does agree with USDA's stick portion. The oil discrepancy is named in the output descriptions and in an FAQ, together with the implied-density test that resolves it, so a reader comparing this page against King Arthur's numbers can see exactly why they differ. Independence: primary. Access: open.
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