Lye (NaOH)
3.10 oz
Water
6.2 oz
Batch
2.0 lbs
3–8% is standard. Higher = more moisturizing but softer bar
2.0–2.5 is typical. Lower = harder bar, faster trace
3–6% of total oil weight
| Oil | Weight | % | Lye |
|---|---|---|---|
| Olive Oil | 10.0 oz | 45% | 1.35 oz |
| Coconut Oil | 5.0 oz | 23% | 0.96 oz |
| Palm Oil | 4.0 oz | 18% | 0.57 oz |
| Shea Butter | 2.0 oz | 9% | 0.26 oz |
| Castor Oil | 1.0 oz | 5% | 0.13 oz |
Handmade artisan soaps sell for $6–$15 per bar at markets and online
NaOH (lye) is caustic. Always wear gloves, goggles, and long sleeves.
Always add lye TO water, never water to lye. Work in a ventilated area.
Keep vinegar nearby (not for neutralizing burns—flush with water first).
Inputs
Result
A 22 oz oil batch with the classic 45/23/18/9/5 ratio needs 3.12 oz of NaOH at 5% superfat. Mixed with 6.2 oz of water, the total batch is 31.4 oz—about 10 bars at under $1 each.
Inputs
Result
A high-olive bastille recipe is the most forgiving for beginners. The 7% superfat and 2.5:1 water ratio give extra working time. The resulting bar is very mild and conditioning, ideal for sensitive skin.
Multiply each oil’s weight by its SAP value (saponification number for NaOH). Sum all the individual lye amounts, then reduce by your superfat percentage. For example: 10 oz olive oil × 0.1353 SAP = 1.353 oz NaOH. With 5% superfat, final lye = total × 0.95.
| Oil | SAP (NaOH) | 10 oz Needs | Bar Quality |
|---|---|---|---|
| Olive | 0.1353 | 1.35 oz | Mild, conditioning |
| Coconut | 0.1910 | 1.91 oz | Bubbly, cleansing |
| Palm | 0.1413 | 1.41 oz | Hard, stable |
| Shea | 0.1282 | 1.28 oz | Creamy, moisturizing |
| Castor | 0.1286 | 1.29 oz | Lather booster |
Most cold process soap recipes use 5% superfat, meaning 5% of the oils remain unsaponified for moisturizing. For sensitive skin, use 7–8%. For a harder, more cleansing bar (laundry soap), use 0–2%. Higher superfat makes softer bars that can go rancid faster.
| Superfat % | Feel | Hardness | Best For |
|---|---|---|---|
| 0–2% | Drying | Very hard | Laundry, cleaning |
| 3–5% | Balanced | Hard | Daily body soap |
| 5–7% | Moisturizing | Medium | Face, sensitive skin |
| 8–10% | Very soft | Soft | Luxury bars |
The standard water:lye ratio is 2:1 (twice as much water as lye by weight). Some soapers use 1.5:1 for harder bars with less cure time, while beginners should stick with 2.5:1 for more working time. For example, if you need 3 oz of lye, use 6 oz of water at 2:1 ratio.
| Water:Lye Ratio | Working Time | Bar Hardness | Skill Level |
|---|---|---|---|
| 1.5:1 | ~5 min | Very hard | Advanced |
| 2.0:1 | ~10–15 min | Hard | Standard |
| 2.5:1 | ~20 min | Medium | Beginner |
| 3.0:1 | ~30 min | Soft | Very slow cure |
A basic cold process soap bar costs $0.50–$1.50 in materials. A 22 oz batch with olive, coconut, and palm oils plus fragrance costs about $8–10 and yields 10 bars—roughly $0.80–$1.00 each. Compare that to $6–$15 for artisan soap at farmers markets.
| Recipe Size | Material Cost | Bars Made | Cost/Bar |
|---|---|---|---|
| Small (16 oz oils) | $6–$8 | 6–8 | $0.80–$1.00 |
| Medium (32 oz oils) | $12–$16 | 12–15 | $0.90–$1.10 |
| Large (48 oz oils) | $18–$24 | 18–22 | $0.95–$1.10 |
Cold process soap needs 4–6 weeks of curing after cutting. During curing, excess water evaporates, the bar hardens, and the pH drops to a mild 8–9. Cut bars 24–48 hours after pouring, then cure on a rack with good airflow. Castile (100% olive) soap benefits from 6–12 months of curing.
| Stage | Timing | Action | Purpose |
|---|---|---|---|
| Unmold | 24–48 hours | Remove from mold | Bar firm enough to handle |
| Cut | Immediately after | Slice into bars | Even sizing |
| Standard Cure | 4–6 weeks | Rack with airflow | Water evaporates, pH drops |
| Castile Cure | 6–12 months | Extended aging | Harder bar, milder feel |
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Last Updated: Mar 11, 2026
This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.