What does the top of the Data Scientist pay scale look like in Illinois?

The 90th percentile lands at $172,220. That tier typically reflects senior roles, specialty certifications, high-cost-of-living metros within the state, or union-negotiated rate cards. Below that, the P75 quartile is $147,130.

Why is the BEA RPP for Illinois different from a single CPI number?

BEA splits regional price parity into three components — goods, services, and rents — reweighted to the BEA's national consumption basket. Illinois's overall index of 98.8 reflects rents 92.4, services 80.4, and goods 101.6.

Where does Illinois rank for Data Scientist pay?

On nominal BLS wages alone, Illinois ranks among the 51 states and DC by median pay. After the BEA cost-of-living adjustment the ordering changes — high-cost states fall, low-cost states rise. Both rankings are shown in the data table on this page.

Is Illinois a 'real-wage arbitrage' state for Data Scientists?

No — Illinois's RPP is close to the national 100 baseline, so nominal and real wages move roughly together. Neither an arbitrage nor a penalty state.

What are the limits of these Data Scientist salary numbers?

BLS OES is an employer survey of W-2 wages — it excludes contractor pay, bonuses outside the base wage definition, equity compensation, and tip income. Self-employed practitioners and gig workers are not represented. For occupations with significant non-W-2 income, the BLS figure is a floor, not a complete picture.

Should I negotiate based on the BLS median for Illinois?

The BLS median is a calibration anchor, not a ceiling. Use it to validate that an offer is in-band — anything well below the P25 in this state is a flag, anything above the P75 typically requires demonstrable specialty depth, niche credentials, or a high-COL metro within Illinois.

When does this data update?

BLS OES releases a new May reference set roughly each spring; we re-run the ETL pipeline within two weeks of release. BEA RPP refreshes annually. The last-synced timestamp at the top of this page reflects the most recent build.

Data Scientist Pay in Illinois: $113K Median + Purchasing Power (2026)

TL;DR

$113,490 is the BLS median wage for Data Scientists in Illinois; $114,924 is the BEA-adjusted purchasing-power equivalent.
Data Scientist ranking: #15 on the BLS table, #18 once cost of living is in.
Cost of living tracks roughly with the national index, so nominal and real wages stay close.
P25-P75 spread runs $82,010 to $147,130; P10 floor $65,420, P90 ceiling $172,220.

Wage breakdown — Illinois

Percentile	Nominal (BLS)	Real (BEA RPP-adjusted)
P10 (entry tier)	$65,420	$66,247
P25 (lower quartile)	$82,010	$83,046
P50 (median)	$113,490	$114,924
P75 (upper quartile)	$147,130	$148,989
P90 (top tier)	$172,220	$174,396
Mean	$119,010	$120,514
Employment	7,390 Data Scientists in Illinois

Cost of living — BEA Regional Price Parity

Component	Illinois index (US = 100)
All-items RPP	98.8
Goods	101.6
Services	80.4
Rents	92.4

Illinois's overall RPP (98.8) is close to the national 100 baseline; nominal and real wage move roughly together.

After-tax take-home — Illinois (2024 BLS · 2024 tax year, single filer)

Layer-by-layer take-home math at the BLS median

Layer	Amount	Note
Gross BLS P50 (Data Scientist)	$113,490	nominal median
Federal income tax	−$16,215	14.3% effective; std deduction $15,750 applied
State income tax	−$5,618	4.95% flat (2026)
FICA (SS 6.2% + Medicare 1.45%)	−$8,682	SS capped at $183,600 wage base
Take-home (after-tax)	$82,975	73.1% of gross
Real take-home (RPP-adjusted)	$84,024	÷ (98.8 / 100) BEA cost-of-living

What the Illinois state-tax burden means for Data Scientist take-home

Mid-band state-tax burden at 5.0% effective. Combined with federal and FICA, take-home is $82,975 (73.1% of gross). After the 98.8 RPP, real take-home is $84,024.

Computed from 2026 IRS federal brackets (Rev. Proc. 2025-32), 2026 state DOR brackets, and 2026 FICA rates. Single filer, standard deduction, no other adjustments. See methodology · tax for limitations (married filers, ITM/SALT itemizers, retirement deferrals, HSA, dependent credits, etc.).

National context

Across the United States, BLS reports a national median of $112,590 for Data Scientists with mean pay of $124,590 and total employment of 233,440. Illinois sits at #15 on nominal pay and #18 on real (cost-adjusted) pay among the 51 states and DC. After cost adjustment, Illinois falls 3 positions — the cost premium eats into the headline wage.

Frequently asked questions

What does the top of the Data Scientist pay scale look like in Illinois?: The 90th percentile lands at $172,220. That tier typically reflects senior roles, specialty certifications, high-cost-of-living metros within the state, or union-negotiated rate cards. Below that, the P75 quartile is $147,130.
Why is the BEA RPP for Illinois different from a single CPI number?: BEA splits regional price parity into three components — goods, services, and rents — reweighted to the BEA's national consumption basket. Illinois's overall index of 98.8 reflects rents 92.4, services 80.4, and goods 101.6.
Where does Illinois rank for Data Scientist pay?: On nominal BLS wages alone, Illinois ranks among the 51 states and DC by median pay. After the BEA cost-of-living adjustment the ordering changes — high-cost states fall, low-cost states rise. Both rankings are shown in the data table on this page.
Is Illinois a 'real-wage arbitrage' state for Data Scientists?: No — Illinois's RPP is close to the national 100 baseline, so nominal and real wages move roughly together. Neither an arbitrage nor a penalty state.
What are the limits of these Data Scientist salary numbers?: BLS OES is an employer survey of W-2 wages — it excludes contractor pay, bonuses outside the base wage definition, equity compensation, and tip income. Self-employed practitioners and gig workers are not represented. For occupations with significant non-W-2 income, the BLS figure is a floor, not a complete picture.
Should I negotiate based on the BLS median for Illinois?: The BLS median is a calibration anchor, not a ceiling. Use it to validate that an offer is in-band — anything well below the P25 in this state is a flag, anything above the P75 typically requires demonstrable specialty depth, niche credentials, or a high-COL metro within Illinois.
When does this data update?: BLS OES releases a new May reference set roughly each spring; we re-run the ETL pipeline within two weeks of release. BEA RPP refreshes annually. The last-synced timestamp at the top of this page reflects the most recent build.

Sources & methodology

U.S. Bureau of Labor Statistics — Occupational Employment and Wage Statistics (OES), SOC 15-2051, 2024 reference period.
U.S. Bureau of Economic Analysis — Regional Price Parities, 2023 vintage (all-items, goods, services, rents).
Real-wage figures = nominal BLS wage ÷ (state RPP / 100).
See the methodology page for full computation details and limitations.

By Marcus Liang · Founder & Editor · Last synced 2026-05-05.

Cross-comparison: see how Illinois Data Scientist pay ranks against the other 254 state × occupation pages on the Real Wage Atlas → — four-way ranking by real wage, after-tax take-home, state-tax savings, and cost-of-living arbitrage.