Can you swap one oil for another in a soap recipe?
Usually, yes, with two conditions. The new oil has to make the same kind of soap, which is a question about its fatty acids; and the lye has to be worked out again, which is a question about its SAP value. Running it through the lye calculator again covers the second; measuring "the same kind of soap" usually means sorting a table by hand. This tool does both: it ranks every oil in the oil properties chart by how close its fatty-acid profile is to the one you're replacing, tries every two-oil blend, and recalculates the recipe.
Each oil is eight numbers: lauric, myristic, palmitic, stearic, ricinoleic, oleic, linoleic, linolenic, in percent. The distance between two oils is the straight-line distance between those eight numbers, in percentage points: palm (44 palmitic, 5 stearic, 39 oleic, 10 linoleic) against lard (28, 13, 46, 6) is √(16² + 8² + 7² + 4²) = 19.6. Because hardness, cleansing, conditioning, bubbly and creamy are all fixed sums of those same acids, two oils that are close here make close bars. For reading the numbers: up to 6 is near-identical, up to 20 close, up to 40 workable, beyond that a different oil. Those bands are ours, calibrated on the swaps soapmakers already trust.
The usual substitutes, measured
| Replacing | With | How often suggested | Distance | Verdict | Biggest difference |
|---|---|---|---|---|---|
| Palm oil | Lard | Widely, and by SoapCalc | 19.6 | close | −16 palmitic |
| Palm oil | Beef tallow | Widely | 25.2 | workable | +17 stearic |
| Palm oil | Cocoa butter | In palm-free recipes | 33.3 | workable | +28 stearic |
| Palm oil | Shea butter | In palm-free recipes | 53.3 | different | −39 palmitic |
| Palm oil | Babassu oil | Soap Queen: “the closest substitute” | 69.9 | different | +50 lauric |
| Coconut oil (76°) | Babassu oil | Widely | 4.2 | near-identical | +2 lauric |
| Coconut oil (76°) | Palm kernel oil | Widely | 7.9 | close | +7 oleic |
| Olive oil | Sunflower oil, high oleic | Widely | 19.5 | close | +14 oleic |
| Olive oil | Canola oil | Often | 17.6 | close | −10 palmitic |
| Olive oil | Rice bran oil | Often, as 1:1 | 38.9 | workable | −31 oleic |
| Olive oil | Sunflower oil | when “high oleic” is dropped | 78.9 | different | +58 linoleic |
| Shea butter | Mango butter | Widely | 5.1 | near-identical | −3 oleic |
| Shea butter | Cocoa butter | Often | 27.5 | workable | +23 palmitic |
| Shea butter | Lard | Soapmaking forum: “nearly identical numbers” | 35.5 | workable | −27 stearic |
Fatty-acid distance in percentage points, from the SoapCalc profiles in this site's oil table. "Biggest difference" is the one acid that moves most, substitute minus original.
Most of the folk list holds up. Babassu and palm kernel really are coconut; mango really is shea; lard really is the nearest thing to palm. Three entries don't. Babassu is not a palm substitute, though Soap Queen's tutorial calls it "the closest". It sits 70 points away against lard's 20, because it is half lauric acid and palm has none. Shea is not a one-for-one palm substitute either: 53 points away, because palm's saturated fat is palmitic and shea's is stearic. Plain sunflower is not olive oil: it's 70% linoleic, and the high-oleic sunflower that is an olive substitute is 94 points away from it under the same name on the shelf. Lard for shea is workable rather than close, though the SoapCalc bars look alike: shea's saturated fat is stearic, lard's is palmitic, 35.5 points apart.
Coconut, palm kernel and babassu are hard because of lauric and myristic acid, short chains that make big, fast, cleansing lather. Palm, tallow, lard, cocoa and shea are hard because of palmitic and stearic, long chains that make a hard, long-lasting, creamy bar and little lather of their own. Both count toward "hardness", so the hardness bar can't tell them apart; the cleansing number can. Swapping the classic bar's palm for babassu takes its cleansing number from 20 to 41, past the top of the customary range. The trace guide shows the same split deciding working time.
What happens if you swap without recalculating the lye?
Here is what skipping the recalculation does. Take the classic bar (35% olive, 30% coconut, 30% palm, 5% castor, 5% superfat), swap one oil, and keep weighing the lye the old recipe called for:
| Swap | Share of the recipe | Lye should change by | Superfat if you don't |
|---|---|---|---|
| Coconut oil (76°) → sunflower oil, high oleic | 30% | -13.8 g | -5.1% |
| Coconut oil (76°) → olive oil | 30% | -13.6 g | -4.9% |
| Coconut oil (76°) → lard | 30% | -12.0 g | -3.6% |
| Palm oil → shea butter | 30% | -4.1 g | 2.2% |
| Coconut oil (76°) → babassu oil | 30% | -2.4 g | 3.4% |
| Olive oil → canola oil | 35% | -0.9 g | 4.4% |
| Palm oil → lard | 30% | -0.2 g | 4.9% |
| Palm oil → babassu oil | 30% | +9.3 g | 10.8% |
| Olive oil → coconut oil (76°) | 35% | +15.9 g | 14.4% |
Classic bar, 1,000 g oils, 143.8 g NaOH at 5% superfat; each row reruns the lye with the new oil's SAP value from the oils table. "Superfat if you don't" is what the new oils make with the old lye weight; negative is lye-heavy.
The pattern is one rule. 69 of the 81 oils the tool can rank have a SAP value between 0.180 and 0.200, so most swaps barely move the lye. Palm for lard changes it by 0.2 g, which is why you'll read that it's fine to skip the calculator for swaps like that. The lauric oils are the exception, at 0.245–0.257. Swap out of coconut without recalculating and you make lye-heavy soap: −4.9% superfat for olive in the coconut slot. Swap into a lauric oil and you under-dose, which makes a soft, greasy bar and nothing worse. The lye-heavy soap guide found that mixing up look-alike oils rarely matters; this is the case where it does, because the two oils aren't look-alikes.
When a two-oil blend beats any single oil
The best answers on the soapmaking forums are blends, worked out by hand: "faux lard", or 70% high-oleic safflower and 30% lard for olive oil. A blend of two oils has a profile exactly between them, so the tool can try every pair at every ratio in 5% steps and keep the closest. It only shows a blend when it beats the best single oil by a clear margin (at least 2 points and a quarter closer), and never with less than 20% of either oil. Here's how the forum's hand-built blends score:
| For | Blend | From | Distance | Best single staple | Tool's best |
|---|---|---|---|---|---|
| Lard | 55% palm oil + 30% shea butter + 15% olive oil | soapmakingforum “faux lard” | 3.8 | Beef tallow (14.8) | 55% beef tallow + 45% avocado oil (4.6) |
| Olive oil | 70% safflower oil, high oleic + 30% lard | soapmakingforum | 3.5 | Sweet almond oil (9.9) | 80% safflower oil, high oleic + 20% palm oil (2.6) |
| Olive oil | 80% safflower oil, high oleic + 20% cocoa butter | Modern Soap Making | 6.9 | Sweet almond oil (9.9) | 80% safflower oil, high oleic + 20% palm oil (2.6) |
Distances from the same eight-acid profiles; the tool's suggestions drawn from oils suppliers and supermarkets stock.
The hand-built blends are good; the forum's regulars know their oils. "Faux lard" at 3.8 beats the best two-oil blend the tool can find (4.6) because it uses three oils, a reminder that the search is limited to pairs. For olive oil the search does better than both hand-built blends: 80% safflower oil, high oleic + 20% palm oil lands at 2.6, against 3.5 for the safflower-and-lard mix. Where a blend really shines is when no single oil comes close. For shea, mango is near-identical already, but 70% kokum with 30% high-oleic safflower is closer still. For a vegan lard swap, the best single oil is avocado at 19.1; 55% avocado oil + 45% cocoa butter gets to 6.0. And for tallow, the closest vegan oil is cocoa butter, at 12.8: close.
Palm oil substitutes, with and without animal fats
If you can use animal fats, lard is palm's nearest substitute and the swap is almost free: 19.6 points apart, 0.2 g less lye, and the classic bar's hardness drops 3 points. Tallow is the next closest. If you can't, the arithmetic is blunt: nothing palm-free and animal-free comes close to palm. The best single staple is avocado oil at 30.8, and the best two-oil blend, 50% cocoa butter + 50% rice bran oil, only reaches 24.7. Palm's profile, nearly half palmitic acid with oleic behind it, just isn't something the vegan oils make.
That's why good palm-free recipes aren't palm recipes with one oil swapped. They are reformulated: the long-chain hardness palm gave comes back from 10–20% of a stearic butter (shea, cocoa, mango or kokum), the rest of palm's share goes to liquid oils, and a water discount or sodium lactate helps the softer bar out of the mold. The recipe builder's palm-free starter is built that way, with shea and cocoa butter doing palm's job. Use this tool to find the nearest oil, then use the recipe builder's quality bars to rebalance the whole blend. That's the step a substitution can't do for you.
Two oils with the same profile make the same bar in the ways a soap calculator can measure, and can still differ in ways it can't. Unsaponifiables: shea carries 5–15% that never becomes soap (the saponification guide shows it in the SAP value); mango carries less. Shelf life: oils close in fatty acids are close in rancidity risk, but grades and freshness differ (the DOS guide has the numbers). Color and scent: red palm, hemp and unrefined oils carry both. And castor has no substitute at all: it is 90% ricinoleic acid and no other oil has any, so the nearest staple is 97 points away. Leave it out or keep it.
The printable substitution chart
SoapmakingToolbox.com · soap oil substitution chart — closest match by fatty acids
| Oil | Lauric + myristic | Palmitic + stearic | Oleic | Linoleic + linolenic | Closest substitute | Closest palm-free, vegan | Best blend |
|---|---|---|---|---|---|---|---|
| Olive oil | 0 | 17 | 69 | 13 | Sweet almond oil (10) | Sweet almond oil (10) | 80% safflower oil, high oleic + 20% palm oil (3) |
| Coconut oil (76°) | 67 | 12 | 8 | 2 | Babassu oil (4) | Babassu oil (4) | — |
| Palm oil | 1 | 49 | 39 | 10 | Lard (20) | Avocado oil (31) | — |
| Lard | 1 | 41 | 46 | 6 | Beef tallow (15) | Avocado oil (19) | 55% beef tallow + 45% avocado oil (5) |
| Beef tallow | 8 | 50 | 36 | 4 | Cocoa butter (13) | Cocoa butter (13) | 65% palm oil + 35% kokum butter (8) |
| Castor oil | 0 | 0 | 4 | 4 · ric. 90 | Ghee / butterfat (97) | Rice bran oil (103) | — |
| Shea butter | 0 | 45 | 48 | 6 | Mango butter (5) | Mango butter (5) | 70% kokum butter + 30% safflower oil, high oleic (1) |
| Cocoa butter | 0 | 61 | 35 | 3 | Beef tallow (13) | Mango butter (25) | 75% lard + 25% soy wax (fully hydrogenated soybean oil) (5) |
| Mango butter | 0 | 49 | 45 | 3 | Shea butter (5) | Shea butter (5) | 55% sunflower oil, high oleic + 45% soy wax (fully hydrogenated soybean oil) (1) |
| Sweet almond oil | 0 | 7 | 71 | 18 | Safflower oil, high oleic (7) | Safflower oil, high oleic (7) | 80% safflower oil, high oleic + 20% argan oil (2) |
| Avocado oil | 0 | 22 | 58 | 12 | Olive oil (13) | Olive oil (13) | 60% sweet almond oil + 40% palm oil (3) |
| Rice bran oil | 1 | 25 | 38 | 36 | Argan oil (12) | Argan oil (12) | 70% sesame oil + 30% palm oil (4) |
| Sunflower oil, high oleic | 0 | 7 | 83 | 5 | Hazelnut oil (10) | Hazelnut oil (10) | — |
| Canola oil | 0 | 6 | 61 | 30 | Peanut oil (12) | Peanut oil (12) | 80% canola oil, high oleic + 20% hemp seed oil (2) |
| Palm kernel oil | 65 | 10 | 15 | 3 | Coconut oil (76°) (8) | Coconut oil (76°) (8) | — |
| Babassu oil | 70 | 15 | 10 | 0 | Coconut oil (76°) (4) | Coconut oil (76°) (4) | — |
| Hemp seed oil | 0 | 8 | 12 | 78 | Soybean oil (20) | Soybean oil (20) | — |
| Apricot kernel oil | 0 | 6 | 66 | 27 | Sweet almond oil (10) | Sweet almond oil (10) | 80% safflower oil, high oleic + 20% grapeseed oil (3) |
Fatty acids in percent (SoapCalc profiles). Distance in brackets: up to 6 near-identical, 20 close, 40 workable, beyond that a different oil. Substitutes drawn from oils suppliers and supermarkets stock; blends shown only where they beat the best single oil clearly. Always recalculate the lye after a swap.