Isopropyl Alcohol Dilution Calculator

Make 70%, or any strength, from 99% or 91% isopropyl alcohol, by volume, for any batch size.

99% → 70%91% → 70%99% → 60%99% → 50%1 L of 70%
Target as

      Reviewed by Andre Taki, Chief Commercial Officer, Alliance Chemical. Densities: Laliberté (2009) and the CRC Handbook; bleach strength from Alliance's TDS. Check the SDS for your lot before mixing.

      02

      Choose The Right IPA Grade

      Most IPA buying mistakes are spec mistakes, not concentration mistakes. Technical grade is fine for cleaning and degreasing; USP is what you want for any skin-contact, medical, or regulated environment.

      Buying Guide

      70% USP is the ready-to-use 70% strength. It is the concentration CDC and infection-control guidance cite most often for surface wipe-downs; the water in it slows evaporation, so surfaces stay wet longer.

      91% USP is the middle tier. It is strong enough for lab and electronics use where less water is preferred, but close enough to 70% that a single dilution step gets you there without extreme ratios.

      99% Technical is the concentrate for facilities that want one stock feeding multiple working strengths — 70% for surface wipe-downs, 50% for cleaning, or near-anhydrous for electronics. Technical grade keeps the price down when USP certification is not required.

      A practical rule: buy 70% USP when that is what you use day-to-day and you do not want to dilute. Buy 99% when you need flexibility and your crew reliably does the dilution math (which this calculator will do for you).

      Isopropyl Alcohol 70% USP Grade

      Isopropyl Alcohol 70% USP Grade

      Ready-to-use 70% with USP pharmacopeial spec — skip the dilution step entirely.

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      Isopropyl Alcohol 91% USP Grade

      Isopropyl Alcohol 91% USP Grade

      USP-grade middle tier for labs, electronics work, and teams that want less water than 70% without jumping to anhydrous.

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      Isopropyl Alcohol 99% Technical Grade

      Isopropyl Alcohol 99% Technical Grade

      Near-anhydrous concentrate for facilities diluting to multiple working strengths or needing low-moisture cleaning solvent.

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      99 percent isopropyl alcohol product image from Alliance Chemical
      99% technical IPA is the flexible stock when one facility needs multiple working strengths. Buy 70% USP ready-to-use if 70% is the only strength you need.
      03

      Common IPA Dilution Targets

      These are the IPA working strengths customers ask about most often. Contact time, substrate, and regulatory context all matter, so verify against your SOP before scaling a batch.

      Common recipes
      Starting Stock Target Typical Use Notes Calculator
      99% isopropyl alcohol 70% Surface wipe-downs The most common working strength. The water in 70% slows evaporation, so surfaces stay wet longer than with 99%. Open
      99% isopropyl alcohol 50% General cleaning and degreasing Faster evaporation and more residual rinse compared to 70%. Not a substitute where a procedure calls for 70%. Open
      91% isopropyl alcohol 70% USP 70% from 91% stock Lower-dilution step for facilities already on 91% USP. Keeps pharmacopeial grade through the working solution. Open
      99% isopropyl alcohol 1:0.414 water Ratio-mode SOP for 70% One part 99% IPA to 0.414 parts water is the algebraic equivalent of 99% → 70%. Useful when your SOP is parts-based. Open
      04

      IPA Handling Reality Check

      IPA is low-toxicity compared to many industrial solvents, but it is still a Class IB flammable liquid with a flash point around 12°C. Ignition, vapor pooling, and static discharge are the failure modes that actually cause incidents.

      Guardrails

      Flammable, not benign. IPA vapor ignites from a spark. Keep containers grounded when transferring, avoid open flames and heat sources, and ventilate enclosed spaces. Do not store 99% IPA near electrical panels or heaters.

      70% is the most common working strength — not higher. Pure 99% evaporates very quickly. The water in 70% keeps a surface wet longer, which is why guidance cites 70% for wipe-downs. Stronger is not better here.

      USP grade matters for skin-contact or medical contexts. Technical grade is fine for industrial cleaning. For wound prep, pharmacy compounding, or anything touching patients or food, verify the USP certification before substituting.

      Dilute with distilled water when it matters. Tap water contains minerals and chlorine residues that can leave streaks on electronics, screens, and optical surfaces. For lab or cleanroom work, distilled or DI water only.

      Questions

      Why do guides call for 70% IPA instead of 99%?
      The water slows evaporation, so a 70% solution keeps a surface wet longer than 99%. That is why CDC and infection-control guidance cite 70% as the target strength.
      How do I dilute 99% IPA to 70% at home?
      Measure parts by volume: roughly 7 parts 99% IPA to 3 parts distilled water gets you near 70%. For precise batches, use the calculator above with your target volume — it returns exact IPA and water amounts.
      Can I use 91% IPA instead of diluting 99%?
      Yes, though 91% is stronger than the 70% most guidance calls for. For most surface cleaning, 91% works fine. If you are following a regulated protocol that specifies 70%, dilute 91% or 99% to hit the target rather than substituting.
      Does Alliance Chemical sell USP-grade IPA?
      Yes. 70% and 91% are USP Grade (pharmacopeial spec). 99% is Technical Grade, which is fine for cleaning and solvent work but not USP-certified. For medical or compounding use, stick with the USP-labeled products.