Last updated: April 22, 2026

How to Plan Oligo Pool Synthesis from Design to QC

Q: What is the difference between array-based and column-based oligo synthesis?

Array-based synthesis uses microarray technology to synthesize thousands to millions of oligonucleotides simultaneously on a solid surface, then cleaves and pools them. Column-based synthesis builds one sequence at a time on controlled-pore glass (CPG) columns using phosphoramidite chemistry. Array synthesis is cost-effective for large pools ($0.03-0.12/oligo) but has higher error rates (~1/200 bases). Column synthesis produces higher purity (>99%) but is expensive for pools ($5-50 per individual oligo).

Use this page when you need to plan an oligo pool synthesis order end to end. It helps you choose a method, screen sequences, compare vendor quotes, set QC thresholds, and decide what to do after delivery. If you need a faster answer on one step, jump to design rules, synthesis methods, vendor comparison, official vendor specs snapshot, cost planning, and troubleshooting.

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Owns `oligo pool synthesis` planning intent across the cluster.

Version

Guide version 2026.04. Last editorial update: April 22, 2026.

Use this page for

Method choice, quote review, QC thresholds, budget planning, and post-delivery decisions.

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Open Research, References, and About for methods, sources, and project boundaries.

Planning an oligo pool synthesis workflow

Plan method choice, vendor quotes, and QC checks before your pool order goes live.

Key Takeaways

•Array-based synthesis (Twist, Agilent) produces 1K-1M oligos per pool at $0.03-0.12 per oligo, ideal for CRISPR libraries, MPRA, and gene assembly.
•Column-based synthesis provides higher purity (>99%) but is limited to individual sequences — use for critical primers and probes, not pools.
•Synthesis error rate increases with oligo length: ~1 error per 200 bases for array synthesis vs ~1 per 500 bases for column synthesis.
•Key QC metrics for pools: representation uniformity (<3-fold CV), dropout rate (<10%), and Gini coefficient (<0.25). The n-1 deletion product is the most common impurity, detectable by mass spectrometry as a -289 to -329 Da shift.
•Design optimization can reduce synthesis failures by 40-60%: avoid homopolymers (>5 nt), extreme GC (<25% or >75%), and strong secondary structures.
•NGS verification at 500-1000x coverage per oligo is essential for confirming pool composition before downstream experiments.

Planning an oligo pool order?

→ Which synthesis method fits my pool?→ Which design checks matter before ordering?→ Which vendor quote should I trust?→ How much should I budget beyond synthesis price?→ How do I review the vendor QC report?→ What should I do after the pool arrives?

Need the shorter task-specific page?

→ Plan the overall workflow before ordering → Check design rules before submission → Choose between array and column synthesis → Compare oligo pool vendors → Estimate cost before requesting quotes → Troubleshoot dropout, skew, and cloning failures

What this guide is not

This page is an educational and decision-support guide. It helps you compare methods, QC expectations, and vendor tradeoffs, but it is not a live quote engine, not a vendor submission portal, and not a replacement for application-specific protocol validation inside your lab.

1. What Oligo Pool Synthesis Includes

Oligo pool synthesis is the large-scale production of many unique oligonucleotide sequences in a single manufacturing process. Unlike traditional column-based synthesis that produces one sequence at a time, array-based platforms synthesize thousands to millions of distinct oligos simultaneously, delivering them as a mixed pool.

This technology enables applications that would be prohibitively expensive with individual oligo synthesis:

CRISPR Libraries

Genome-wide knockout, CRISPRa/i, and tiling libraries with 10K-200K sgRNA oligos per pool.

Gene Assembly

Overlapping oligos for Gibson assembly or Golden Gate cloning of synthetic genes (1-10 kb).

MPRA / Reporter Assays

Massively parallel reporter assays testing thousands of regulatory element variants simultaneously.

Targeted Sequencing

Hybridization capture panels and amplicon sequencing panels for NGS target enrichment.

Mutagenesis Libraries

Saturation mutagenesis, deep mutational scanning (DMS), and variant libraries for protein engineering.

DNA Data Storage

Encoding digital information in synthetic DNA sequences using large oligo pools as the storage medium.

2. Which Synthesis Method Fits Your Pool?

Use this comparison when you need to decide whether array-based or column-based synthesis fits your pool size, oligo length, acceptable error rate, purification needs, and downstream workflow.

Feature	Array-Based Synthesis	Column-Based Synthesis
Scale	1K - 1M oligos per pool	1 oligo per column
Max Length	150-350 nt (platform-dependent)	100-200+ bp
Error Rate	~1 per 200 bases	~1 per 500 bases
Coupling Efficiency	98.5-99.5% per step	99.0-99.8% per step
Full-Length %	30-70% (length-dependent)	70-95%
Cost per Oligo	$0.03-0.12	$5-50
Turnaround	2-4 weeks	1-3 days
Purification	Pool-level only	Individual (PAGE, HPLC)
Best For	Libraries, pools, high-throughput	Primers, probes, critical sequences

Coupling Efficiency and Full-Length Yield

Full-length % = (Coupling Efficiency)^(N-1) x 100

Where N = oligo length in nucleotides. For a 100-mer at 99% coupling efficiency:

Full-length % = 0.99^99 x 100 = 37%. At 99.5% efficiency: 0.995^99 x 100 = 61%. This is why coupling efficiency is the single most important synthesis quality parameter.

Use our Error Rate Calculator to compute full-length percentage for your specific oligo length and coupling efficiency.

3. Which Design Checks Should You Run Before Ordering?

Sequence composition directly affects synthesis quality. Problematic sequences cause higher error rates, reduced representation, and complete dropouts from the pool. Pre-synthesis screening can eliminate 90% of quality issues.

Sequence Feature	Acceptable	Problematic	Consequence	Tool to Check
GC Content	30-70%	<25% or >75%	Synthesis failure, low yield	GC Analyzer
Homopolymer	≤4 bases	≥5 bases (esp. poly-G)	Deletion errors, dropouts	Batch QC
Secondary Structure	ΔG > -3 kcal/mol	ΔG < -5 kcal/mol	Incomplete synthesis	Structure Predictor
Tandem Repeats	≤4 bp repeat unit	>6 bp repeat unit	Slippage errors	Batch QC
Palindromes	≤6 bp	>8 bp	Hairpin during synthesis	Structure Predictor
Length Uniformity	±5 bp within pool	>20 bp range	Amplification bias	Batch QC

We recommend running all pool sequences through our Batch Sequence QC tool before placing a synthesis order. The tool screens for all the above issues simultaneously and flags sequences that need redesign, saving costly re-synthesis.

4. Which QC Metrics Matter After Synthesis?

After synthesis, use these metrics to decide whether the delivered pool is ready for cloning, capture, screening, or another downstream workflow.

Metric	Definition	Target	Action if Failed
Representation	% of designed oligos detected (≥50 reads)	≥90%	Redesign missing sequences
Dropout Rate	% of oligos with <10 reads	<10%	Increase sequencing depth
Uniformity (CV)	Coefficient of variation of read counts	<3-fold (10th-90th %ile)	Sub-pool problematic oligos
Gini Coefficient	Inequality measure (0 = perfect, 1 = one oligo only)	<0.25 (ideal <0.15)	Check synthesis platform
Sequence Accuracy	% of reads matching designed sequence	>85% perfect match	Adjust error-rate expectations
NGS Depth	Average reads per designed oligo	500-1000x	Sequence more deeply

Use our Uniformity Estimator to predict expected representation based on your pool size and sequencing depth, and our Error Rate Calculator to interpret synthesis fidelity results.

5. How Should You Compare Vendors and Quotes?

Compare vendors using pool size, oligo length, included QC, lead time, and the format of the data you receive back, not just the headline price per oligo.

Vendor	Pool Size	Max Length	Cost/Oligo	NGS QC	Lead Time
Twist Bioscience	1K-300K	350 nt	$0.04-0.08	Included (500x)	2-3 weeks
Agilent SurePrint	Up to 1M	200 bp	$0.03-0.06	Optional add-on	3-4 weeks
CustomArray (GenScript)	12K-2M	230 bp	$0.08-0.12	Available	2-3 weeks
IDT (xGen)	Up to 200K	200 bp	$0.06-0.10	Included	2-3 weeks

Pricing as of Q1 2026; varies by pool size, oligo length, and account terms. Contact vendors for current quotes. See our Vendor Directory for detailed comparison.

💡 Pro Tip: Request a pilot pool (500-1K oligos) from 2-3 vendors before committing to a large order. Compare their NGS QC reports side-by-side — representation uniformity varies significantly between vendors for the same sequences. A $200-500 pilot can save thousands in failed large-scale synthesis.

⚠️ Pitfall: Don't assume "included NGS QC" means the same thing across vendors. Twist provides 500x coverage with a downloadable report; some vendors only report aggregate metrics (mean representation) without per-oligo data. Always ask for per-sequence read count data.

6. How Much Should You Budget Beyond Synthesis Price?

Budget using the full workflow, not the list price alone. Use this table to estimate the combined cost of synthesis, QC, and downstream handling for common pool sizes:

Pool Size	Synthesis Cost	NGS QC (500x)	Amplification / Cloning	Total Estimate
1K (pilot)	$40-120	Included / $150	$50-100	$200-400
10K (focused screen)	$400-1,200	Included / $300	$200-500	$800-2,000
100K (genome-wide)	$4,000-12,000	Included / $800	$500-1,200	$5,000-14,000
300K (deep tiling)	$12,000-36,000	$1,500-3,000	$1,000-2,500	$15,000-42,000

💡 Pro Tip: For pools >50K oligos, negotiate volume discounts directly with the vendor's sales team — published list prices can often be reduced 20-40% for academic accounts or multi-pool orders. Ask about "failed oligo credit" policies — Twist offers re-synthesis credit for oligos with <50 reads.

⚠️ Hidden cost: Budget for 2-3x the sequencing depth you think you need. The first NGS run often reveals 5-15% of oligos are underrepresented, requiring a second round of deeper sequencing before you can confidently proceed to downstream experiments.

7. Worked Example: Planning a 10K CRISPR Library Order

Let's walk through the complete process of ordering a focused CRISPR knockout library targeting all human kinases (~500 genes × 20 sgRNAs = 10,000 oligos).

Step 1: Design sgRNA Sequences

Use CRISPick (Broad Institute) to design 20 sgRNAs per gene. Export as FASTA. Each oligo = 5' adapter (24 nt) + sgRNA spacer (20 nt) + scaffold overlap (20 nt) + 3' adapter (24 nt) = 88 nt total.

# Example oligo structure

5'-CACCGNNNNNNNNNNNNNNNNNNNGTTTTAGAGCTAGAAATAGC-3'

BsmBI 20nt spacer scaffold overlap

Step 2: Pre-Synthesis QC Screen

Upload all 10K sequences to our Batch QC Tool. Typical results for a kinase library:

Pass

9,650 (96.5%)

Warning (high GC)

280 (2.8%)

Fail (homopolymer)

50 (0.5%)

Fail (structure)

20 (0.2%)

Redesign the 70 failing oligos using alternative sgRNA candidates from CRISPick.

Step 3: Place the Order

For a 10K pool at 88 nt, Twist Bioscience is a strong choice: $0.06/oligo × 10,000 = $600 synthesis + included NGS QC. Submit as CSV/FASTA. Expected turnaround: 2-3 weeks.

File format tip: Twist requires CSV with columns: Name, Sequence, Pool Name. No spaces in names. Agilent accepts FASTA. Use our Format Converter to switch between formats.

Step 4: Receive & Validate

Pool arrives lyophilized. Resuspend in TE buffer to 10 nM. Amplify with 8 PCR cycles (Q5 polymerase). The vendor's NGS report should show: ≥95% representation, Gini <0.2, <5% dropout. If dropout exceeds 10%, jump to our dropout recovery steps.

💡 Pro Tip: Always include 50-100 non-targeting control sgRNAs in your library design. These serve as negative controls for hit calling and also help assess representation uniformity across the pool — controls should have roughly average representation if synthesis was uniform.

8. What to Do After Your Pool Arrives

Resuspension

Resuspend lyophilized pool in TE buffer (10 mM Tris-HCl, 0.1 mM EDTA, pH 8.0). Mix gently, avoid vortexing. Use our Dilution Calculator for concentration calculations.

Use Dilution Calculator →

PCR Amplification

Amplify with minimal cycles (6-10) using high-fidelity polymerase (Q5, KAPA HiFi). Monitor by qPCR to avoid over-amplification, which causes representation bias.

Use Tm Calculator →

Size Selection & Cleanup

Gel-extract or bead-purify (AMPure XP) to remove primer dimers and truncation products. Verify on Bioanalyzer or TapeStation.

NGS Verification

Sequence at 500-1000x depth per oligo. Analyze representation, dropout, and uniformity metrics. Resynthesize failed sequences if needed.

Use Uniformity Estimator →

Downstream Application

Proceed to cloning (CRISPR libraries), assembly (gene synthesis), or direct use (capture probes) based on your application.

⚠️ Pitfall: Over-amplification is the #1 cause of representation skew in oligo pools. Never exceed 10 PCR cycles. Monitor amplification in real-time by running a parallel qPCR with 1 µL of pool — stop when the curve begins to plateau (typically cycles 6-8). If you see a plateau before cycle 6, your input is too low.

9. How to Recover from Dropout and Skew

Pool dropout rates above 10-15% can compromise downstream experiments. Before re-ordering, try these recovery strategies:

📋 Dropout Triage Protocol (click to expand)▾

1. Characterize the dropouts

Export the list of missing/underrepresented oligos. Check for common patterns: high GC (>70%), homopolymers (poly-G ≥4), strong secondary structures (ΔG < -5 kcal/mol). If >80% of dropouts share a sequence feature, the issue is design — not synthesis.

2. Increase sequencing depth

Some "dropouts" are actually present but at very low abundance. Re-sequence at 2-5x your original depth. If oligos appear at 5-50 reads (vs 0), they're "underrepresented" not "dropped out."

3. Adjust amplification

If uniformity (Gini >0.3) is poor despite adequate depth, the issue may be amplification bias. Try: (a) reduce cycles from 10 to 6-8, (b) use emulsion PCR to suppress bias, (c) add 5% DMSO if GC-rich oligos are disproportionately underrepresented.

4. Spike-in rescue

For <500 true dropouts: order them individually as column-synthesized oligos ($5-10 each) and spike into the pool at equimolar ratio. This is cheaper than re-synthesis of the entire pool.

5. Decision: Proceed or re-order?

Proceed if: ≥85% representation and dropouts are randomly distributed (no pathway bias).
Re-order if: <85% representation OR dropouts cluster in critical gene sets. Redesign flagged sequences before re-synthesis.

💡 Pro Tip: Keep a "dropout watchlist" across synthesis batches. If the same oligos consistently drop out from different vendors, the sequences themselves are problematic — no vendor can synthesize them reliably. Consider codon-optimizing or shifting the target region.

10. Which File Format Should You Send Each Vendor?

Each vendor has slightly different requirements for order submission. Match the vendor's expected file format before you upload so your order does not get delayed in review.

Spec	Twist Bioscience	IDT oPools	Agilent SurePrint	GenScript
Upload format	CSV/XLSX (Name, Sequence)	CSV (Name, Sequence, Pool)	FASTA or CSV	Excel (template required)
Sequence direction	5′→3′ only	5′→3′ only	5′→3′ only	5′→3′ only
Max seqs per file	Unlimited	~25,000	~244,000	~10,000
Name requirements	Alphanumeric + underscore	Alphanumeric, ≤50 char	No special characters	Alphanumeric, ≤30 char
Delivery format	Lyophilized pool, single tube	Lyophilized pool, single tube	Solution in 96-well plate	Lyophilized, single tube
Resuspension vol.	TE buffer, user-defined	TE buffer, user-defined	Pre-dissolved	TE buffer, user-defined
Included QC data	NGS + yield report	NGS + COA	Yield estimate only	COA only
Reorder discount	15-20% repeat orders	10% for reorders	Volume-based	Negotiable

Specifications as of 2026. Use our Vendor Format Adapter to auto-convert your sequence list into any vendor's required format.

💡 Pro Tip: Always include 3-5 "sentinel sequences" — unique barcodes not in your experimental set — to independently verify pool identity upon delivery. If your sentinel reads are absent or at wrong ratios, you may have received the wrong pool.

11. Frequently Asked Questions

What is the difference between array-based and column-based oligo synthesis?▾

Array-based synthesis uses microarray technology to synthesize thousands to millions of oligonucleotides simultaneously on a solid surface, then cleaves and pools them. Column-based synthesis builds one sequence at a time on controlled-pore glass (CPG) columns using phosphoramidite chemistry. Array synthesis is cost-effective for large pools ($0.03-0.12/oligo) but has higher error rates (~1/200 bases). Column synthesis produces higher purity (>99%) but is expensive for pools ($5-50 per individual oligo).

How many oligos can be in a single pool?▾

Pool capacity depends on the vendor and platform: Twist Bioscience supports 1K-300K oligos per pool, Agilent SurePrint handles up to 1M features per array, and CustomArray supports 12K-2M oligos. For most CRISPR libraries (70K-200K guides) and targeted panels (500-10K), any major vendor can accommodate your needs. Larger pools may require splitting across multiple synthesis runs.

What is the maximum oligo length for pool synthesis?▾

Maximum length varies by platform: Twist supports up to 350 nt, Agilent SurePrint up to 200 bp, and GenScript (CustomArray) up to 230 bp. However, synthesis quality decreases with length — error rates roughly double for every 50 bp increase. For best results, keep oligos under 150 bp when possible. Most CRISPR library oligos (spacer + scaffold) are 80-120 bp, well within all platforms' capabilities.

How do I assess oligo pool quality after synthesis?▾

Perform NGS verification at 500-1000x coverage per oligo. Key metrics: (1) Representation — ≥90% of designed oligos detected at ≥50 reads; (2) Dropout rate — <10% of oligos with <10 reads; (3) Uniformity — coefficient of variation (CV) <3-fold between 10th-90th percentile; (4) Gini coefficient — <0.25 (ideal <0.15); (5) Sequence accuracy — >85% perfect match reads. Use our Error Rate Calculator to interpret synthesis quality data.

What sequences should I avoid in pool synthesis?▾

Avoid these problematic sequences that cause synthesis failures: (1) Homopolymer runs >5 bases (especially poly-G and poly-C); (2) Extreme GC content (<25% or >75%); (3) Strong secondary structures (hairpins with ΔG < -3 kcal/mol); (4) Tandem repeats and palindromes >8 bp; (5) Very high complexity regions requiring precise synthesis. Screen all sequences with our Batch Sequence QC tool before ordering.

How much does oligo pool synthesis cost?▾

Cost depends on pool size, oligo length, and vendor. Approximate pricing (2026-2026): Twist Bioscience $0.04-0.08/oligo (1K-300K pool), Agilent SurePrint $0.03-0.06/oligo (100K+ pools), CustomArray $0.08-0.12/oligo (mid-scale pools). Volume discounts apply for larger orders. NGS QC is included with some vendors (Twist) or available as an add-on. Compare options on our Vendors page.

Method & Governance Snapshot

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This page owns the synthesis-planning modifier. The broader head term stays on /oligo-pools, while vendor-shortlisting lives on /oligo-pools/vendor-comparison.

How to verify or refresh this page

Refresh vendor-sensitive claims against current public materials before acting on price, length, or turnaround details. Start from the 2026 vendor specs snapshot for vendor-page evidence, then move into the Research hub.

Related Tools

Batch Sequence QC

Screen pool sequences for GC extremes, homopolymers, repeats, and quality issues.

Error Rate Calculator

Calculate full-length percentage and coupling efficiency for oligo synthesis.

Uniformity Estimator

Predict pool representation uniformity based on size and sequencing depth.

Coverage Calculator

Determine required library size for statistical coverage of your target space.

Format Converter

Convert between FASTA, CSV, and vendor-specific formats for synthesis orders.

Vendor Format Adapter

Format oligo pool orders for specific vendor submission requirements.

Next Pages to Open

Continue with the upstream design, vendor, cost, or troubleshooting page that matches the next stage of the pool order.