diff --git a/public/java/src/org/broadinstitute/sting/gatk/walkers/genotyper/UnifiedGenotyper.java b/public/java/src/org/broadinstitute/sting/gatk/walkers/genotyper/UnifiedGenotyper.java
index e3d0efaa1..8df501e1b 100755
--- a/public/java/src/org/broadinstitute/sting/gatk/walkers/genotyper/UnifiedGenotyper.java
+++ b/public/java/src/org/broadinstitute/sting/gatk/walkers/genotyper/UnifiedGenotyper.java
@@ -40,6 +40,7 @@ import org.broadinstitute.sting.utils.SampleUtils;
 import org.broadinstitute.sting.utils.baq.BAQ;
 import org.broadinstitute.sting.utils.codecs.vcf.*;
 import org.broadinstitute.sting.utils.variantcontext.VariantContext;
+import org.broadinstitute.sting.utils.variantcontext.VariantContextUtils;
 
 import java.io.PrintStream;
 import java.util.*;
@@ -216,7 +217,7 @@ public class UnifiedGenotyper extends LocusWalker<List<VariantCallContext>, Unif
             verboseWriter.println("AFINFO\tLOC\tREF\tALT\tMAF\tF\tAFprior\tMLE\tMAP");
 
         annotationEngine = new VariantAnnotatorEngine(Arrays.asList(annotationClassesToUse), annotationsToUse, annotationsToExclude, this, getToolkit());
-        UG_engine = new UnifiedGenotyperEngine(getToolkit(), UAC, logger, verboseWriter, annotationEngine, samples, UnifiedGenotyperEngine.DEFAULT_PLOIDY);
+        UG_engine = new UnifiedGenotyperEngine(getToolkit(), UAC, logger, verboseWriter, annotationEngine, samples, VariantContextUtils.DEFAULT_PLOIDY);
 
         // initialize the header
         Set<VCFHeaderLine> headerInfo = getHeaderInfo();
diff --git a/public/java/src/org/broadinstitute/sting/gatk/walkers/genotyper/UnifiedGenotyperEngine.java b/public/java/src/org/broadinstitute/sting/gatk/walkers/genotyper/UnifiedGenotyperEngine.java
index d4206e8ef..e561fc511 100755
--- a/public/java/src/org/broadinstitute/sting/gatk/walkers/genotyper/UnifiedGenotyperEngine.java
+++ b/public/java/src/org/broadinstitute/sting/gatk/walkers/genotyper/UnifiedGenotyperEngine.java
@@ -50,8 +50,6 @@ import java.util.*;
 
 public class UnifiedGenotyperEngine {
     public static final String LOW_QUAL_FILTER_NAME = "LowQual";
-    
-    public static final int DEFAULT_PLOIDY = 2;
 
     public enum OUTPUT_MODE {
         /** produces calls only at variant sites */
@@ -111,7 +109,7 @@ public class UnifiedGenotyperEngine {
     // ---------------------------------------------------------------------------------------------------------
     @Requires({"toolkit != null", "UAC != null"})
     public UnifiedGenotyperEngine(GenomeAnalysisEngine toolkit, UnifiedArgumentCollection UAC) {
-        this(toolkit, UAC, Logger.getLogger(UnifiedGenotyperEngine.class), null, null, SampleUtils.getSAMFileSamples(toolkit.getSAMFileHeader()), DEFAULT_PLOIDY*(SampleUtils.getSAMFileSamples(toolkit.getSAMFileHeader()).size()));
+        this(toolkit, UAC, Logger.getLogger(UnifiedGenotyperEngine.class), null, null, SampleUtils.getSAMFileSamples(toolkit.getSAMFileHeader()), VariantContextUtils.DEFAULT_PLOIDY*(SampleUtils.getSAMFileSamples(toolkit.getSAMFileHeader()).size()));
     }
 
     @Requires({"toolkit != null", "UAC != null", "logger != null", "samples != null && samples.size() > 0","ploidy>0"})
diff --git a/public/java/src/org/broadinstitute/sting/utils/variantcontext/GenotypeLikelihoods.java b/public/java/src/org/broadinstitute/sting/utils/variantcontext/GenotypeLikelihoods.java
index 7aa0b2605..a6b2bbb21 100755
--- a/public/java/src/org/broadinstitute/sting/utils/variantcontext/GenotypeLikelihoods.java
+++ b/public/java/src/org/broadinstitute/sting/utils/variantcontext/GenotypeLikelihoods.java
@@ -278,6 +278,10 @@ public class GenotypeLikelihoods {
 
     public static int calculateNumLikelihoods(final int numAlleles, final int ploidy) {
 
+        // fast, closed form solution for diploid samples (most common use case)
+        if (ploidy==2)
+            return numAlleles*(numAlleles+1)/2;
+
         if (numAlleles == 1)
             return 1;
         else if (ploidy == 1)
diff --git a/public/java/src/org/broadinstitute/sting/utils/variantcontext/VariantContextUtils.java b/public/java/src/org/broadinstitute/sting/utils/variantcontext/VariantContextUtils.java
index 2a121b6b0..584e76cf9 100755
--- a/public/java/src/org/broadinstitute/sting/utils/variantcontext/VariantContextUtils.java
+++ b/public/java/src/org/broadinstitute/sting/utils/variantcontext/VariantContextUtils.java
@@ -30,7 +30,6 @@ import org.apache.commons.jexl2.JexlEngine;
 import org.apache.log4j.Logger;
 import org.broad.tribble.util.popgen.HardyWeinbergCalculation;
 import org.broadinstitute.sting.commandline.Hidden;
-import org.broadinstitute.sting.gatk.walkers.genotyper.UnifiedGenotyperEngine;
 import org.broadinstitute.sting.utils.*;
 import org.broadinstitute.sting.utils.codecs.vcf.AbstractVCFCodec;
 import org.broadinstitute.sting.utils.codecs.vcf.VCFConstants;
@@ -48,6 +47,8 @@ public class VariantContextUtils {
     public final static String MERGE_FILTER_PREFIX = "filterIn";
 
     final public static JexlEngine engine = new JexlEngine();
+    public static final int DEFAULT_PLOIDY = 2;
+
     static {
         engine.setSilent(false); // will throw errors now for selects that don't evaluate properly
         engine.setLenient(false);
@@ -1123,7 +1124,7 @@ public class VariantContextUtils {
             }
 
             // calculateNumLikelihoods takes total # of alleles. Use default # of chromosomes (ploidy) = 2
-            final int numLikelihoods = GenotypeLikelihoods.calculateNumLikelihoods(1+numOriginalAltAlleles, UnifiedGenotyperEngine.DEFAULT_PLOIDY);
+            final int numLikelihoods = GenotypeLikelihoods.calculateNumLikelihoods(1+numOriginalAltAlleles, DEFAULT_PLOIDY);
             for ( int PLindex = 0; PLindex < numLikelihoods; PLindex++ ) {
                 final GenotypeLikelihoods.GenotypeLikelihoodsAllelePair alleles = GenotypeLikelihoods.getAllelePair(PLindex);
                 // consider this entry only if both of the alleles are good