D.A. Davidson 19th Annual Financial Services Conference Denver, CO May 9th -11th, 2017

This presentation contains forward-looking statements, which are included in accordance with the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995. In some cases, you can identify forward-looking statements by terminology such as “may,” “will,” “should,” “could,” “expects,” “plans,” “intends,” “anticipates,” “believes,” “estimates,” “predicts,” “potential,” or “continue,” or the negative of such terms and other comparable terminology. These forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause the Company’s actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements. Such factors include, among others, the following: failure to maintain adequate levels of capital and liquidity to support the Company’s operations; general economic and business conditions in those areas in which the Company operates, including the impact of global and national economic conditions on our local economy; demographic changes; competition; fluctuations in interest rates; continued ability to attract and employ qualified personnel; ability to receive regulatory approval for the bank subsidiary to declare dividends to the Company; adequacy of the allowance for loan losses, changes in credit quality and the effect of credit quality on the provision for credit losses and allowance for loan losses; changes in governmental legislation or regulation, including, but not limited to, any increase in FDIC insurance premiums; changes in accounting policies and practices; changes in business strategy or development plans; failure or inability to complete mergers or other corporate transactions; failure or inability to realize fully the expected benefits of mergers or other corporate transactions; changes in the securities markets; changes in consumer spending, borrowing and savings habits; the availability of capital from private or government sources; competition for loans and deposits and failure to attract or retain loans and deposits; failure to recognize expected cost savings; changes in the financial performance and/or condition of our borrowers and the ability of our borrowers to perform under the terms of their loans and terms of other credit agreements; changes in oil and natural gas prices; political instability, acts of war or terrorism and natural disasters; and additional “Risk Factors” referenced in the Company’s most recent Annual Report on Form 10-K filed with the Securities and Exchange Commission, as supplemented from time to time. When relying on forward-looking statements to make decisions with respect to the Company, investors and others are cautioned to consider these and other risks and uncertainties. The Company can give no assurance that any goal or plan or expectation set forth in any forward-looking statement can be achieved and readers are cautioned not to place undue reliance on such statements, which speak only as of the date made. The forward-looking statements are made as of the date of this presentation, and, except as may otherwise be required by law, the Company does not intend, and assumes no obligation, to update the forward-looking statements or to update the reasons why actual results could differ from those projected in the forward-looking statements. Investors and security holders are urged to read the Company’s Annual Report on Form 10-K, Quarterly Reports on Form 10-Q and other documents filed by the Company with the SEC. The documents filed by the Company with the SEC may be obtained at the Company’s website at www.gbnk.com or at the SEC's website at www.sec.gov. These documents may also be obtained free of charge from the Company by directing a request to: Guaranty Bancorp, 1331 Seventeenth St., Suite 200, Denver, CO 80202, Attention: Christopher Treece/Investor Relations; Telephone 303-675-1194. Forward Looking Statements 2

Recent Price $ 25.40 1 Tangible Book Value Per Share $10.13 2 Price to Tangible Book Value Per Share 2.51 x1 1Q 2017 diluted earnings per share (EPS) – GAAP $0.35 May 2017 Quarterly Per Share Dividend $0.125 Dividend Yield 1.97% 1 Market Capitalization: $721.2 million 1, 3 Consensus Price Target $27.00 4 2017 EPS Consensus $1.45 4 2018 EPS Consensus $1.59 4 Price to 2017 consensus earnings 17.52 x1, 4 Price to 2018 consensus earnings 15.97 x1, 4  Guaranty Bancorp – About Us 3 1 Based on May 5, 2017 closing price. 2 See the accompanying reconciliation of non-GAAP measurements to GAAP. 3 Based on 28,393,278 shares outstanding on March 31, 2017. 4 NASDAQ consensus of analyst earnings expectations as of May 5, 2017 (20.00) 0.00 20.00 40.00 60.00 80.00 100.00 May-14 Aug-14 Nov-14 Feb-15 May-15 Aug-15 Nov-15 Feb-16 May-16 Aug-16 Nov-16 Feb-17 May-17 GBNK Stock Performance  GBNK (+98.20%) KBW Nasdaq Bank (+35.22%) S&P 500 Bank (+36.08%) About Us – Guaranty Bancorp

Guaranty Bancorp is uniquely positioned in the Colorado market: .32 branches strategically located on the thriving Colorado Front Range, which encompasses 80% of the state’s population .Asset Size: $3.4 billion .Gross Loans: $2.6 billion .Total Deposits: $2.8 billion .Capital: $358.8 million 4 About Us – Guaranty Bancorp. 

Loan growth momentum .Net loan growth during the12 months ended March 31, 2017 measured $294.1 million, or 16.1%, excluding $445.5 million in loans acquired in Home State Bancorporation (Home State) transaction .Loan to deposit ratio of 93.0% as of March 31, 2017 .Strong asset quality continues to improve (ratios as of March 31, 2017) .Nonperforming assets to total assets of 0.16%.Classified asset ratio of 8.24% .Allowance to total loans of 0.90% .Allowance + unaccreted loan discount to total loans of 1.43% .Nonperforming loans to total loans, net of deferred costs and fees of 0.20% .Strong core deposit mix.Noninterest bearing deposits comprised 31.4% of total deposits at March 31, 2017 .Deposit growth over the past 12 months of $123.2 million, or 6.6%, excluding $769.7 million of deposits assumed in the September 2016 Home State transaction .Time deposits comprised 14.8% of total deposits at March 31, 2017 .Cost of deposits 1 remained low at 23 bps during the first quarter 2017 5 1 Including noninterest-bearing deposits. Guaranty Bancorp - Investment Considerations 

$500,000 600,000 $700,000 $800,000 $900,000 $1,000,000 $1,100,000 $1,200,000 $1,300,000 $1,400,000 $1,500,000 $1,600,000 $1,700,000 $1,800,000 $1,900,000 $2,000,000 $2,100,000 $2,200,000 $2,300,000 $2,400,000 $2,500,000 $2,600,000 $2,700,000 Mar-15 Jun-15 Sep-15 Dec-15 Mar-16 Jun-16 Sep-16 Dec-16 Mar-17 Total Loans Home State Aquired Loans Guaranty Bancorp – Investment Considerations Loan Composition & Growth ($ in thousands) 6 Since 3/31/15 loans net of deferred costs and fees have grown $1.0 billion 32.7% annualized (18.3% annualized without Home State) Commercial & Industrial 14.9% Owner Occupied CRE 13.7% CRE Office 9.9% CRE Retail 12.7% CRE Industrial 3.3% CRE Healthcare 3.7% CRE Other 9.3% Residential Mortgage 15.3% Multi Family 4.6% Construction 4.5% Other 4.8% HELOC 3.3% ‘’‘’’’’’’’''''''''''''''''''''''''''Loans by Type'‘’’’'''''''''''''''''''''''‘;;;;;; Consumer 8.5% Business Banking 40.0% Middle Market 12.1% Real Estate 23.0% Private Banking 16.4% _____ Loans by Business Line_ ______ 

$500,000 $600,000 $700,000 $800,000 $900,000 $1,000,000 $1,100,000 $1,200,000 $1,300,000 $1,400,000 $1,500,000 $1,600,000 $1,700,000 $1,800,000 $1,900,000 $2,000,000 $2,100,000 $2,200,000 $2,300,000 $2,400,000 $2,500,000 $2,600,000 $2,700,000 $2,800,000 $2,900,000 Mar-15 Jun-15 Sep-15 Dec-15 Mar-16 Jun-16 Sep-16 Dec-16 Mar-17 Total Deposits Home State Aquired Deposits 7 Since 03/31/15 total deposits have grown $1.0 billion Guaranty Bancorp – Investment Considerations Deposit Composition & Growth ($ in thousands) 30.3% annualized (8.0% annualized without Home State) Noninterest-bearing demand 31.4% Interest-bearing demand and NOW 29.8% Money market 17.7% Savings 6.4% Time 14.7% ;;;;;;;;;;;;;;;;;;;''''''''Deposits by Type''''''‘;;;;;;;;;;;;;;;;;;;; Consumer 54.1% Business Banking 26.6% Middle Market 2.9% Real Estate 2.7% Private Banking 13.7% _____ _ _ __Deposits by Business Line ______ 

8 Guaranty Bancorp – Investment Considerations Select Credit Metrics 1 Nonperforming assets excluding performing TDRs (nonaccrual loans, real estate owned and repossessed assets). Reduction from $33.5 mm to $5.4 mm $13.7 $15.5 $12.6 $14.5 $5.2 $5.1 $19.6 $4.5 $2.2 $0.7 $0.6 $0.3 $0.0 $5.0 $10.0 $15.0 $20.0 $25.0 $30.0 $35.0 2012 2013 2014 2015 2016 2017 Nonperforming Assets ($mm) Nonaccrual OREO 1.78% 1.04% 0.70% 0.64% 0.17% 0.16% 0.00% 0.50% 1.00% 1.50% 2.00% 2012 2013 2014 2015 2016 2017 Nonperforming Assets1 /Total Assets (%) 

.Stable Net Interest Margin .Improved net interest margin to 3.65% in the first quarter 2017 compared to 3.58% in prior quarter and 3.60% in the first quarter 2016 .Anchored by low cost of deposits of 0.23% in the first quarter 2017 .Strong capital structure supportive of future growth (ratios as of March 31, 2017) .Tangible Common Equity Ratio of 8.65% 1 .GAAP Equity Ratio of 10.56% .Total Risk-Based Capital Ratio of 13.44% .Leverage Ratio of 9.83% .Tier 1 Common Equity Ratio of 10.39% .Noninterest income growth .Investment advisory fees .Continued focus on growth in investment management and trust fee income through organic growth .Gains on the sales of SBA loans remain strong - Guaranty Bank is a Preferred Lender by the SBA .Treasury Management income increased 27.0% to $0.7 million in first quarter 2017 as compared to first quarter 2016 .Expense management .Improved efficiency ratio to 55.33% in the first quarter 2017 compared to 59.92% in the first quarter 2016 .Continue to pursue bank and non-bank acquisition opportunities 9 1 See accompanying reconciliation of non-GAAP financial measurements to GAAP. Guaranty Bancorp - Investment Considerations 

Guaranty Bancorp – Investment Considerations Net Interest Income ($ in thousands) 10 1 Cost of Funds calculated as interest expense over interest bearing liabilities plus demand deposits. 4.06% 3.65% 0.23% 0.43% 1 15,000 17,000 19,000 21,000 23,000 25,000 27,000 29,000 0.00% 0.50% 1.00% 1.50% 2.00% 2.50% 3.00% 3.50% 4.00% 4.50% 2Q15 3Q15 4Q15 1Q16 2Q16 3Q16 4Q16 1Q17 Net Interest Income Yield on Interest Earning Assets Net Interest Margin Cost of Funds Cost of Total Deposits 

Guaranty Bancorp – Investment Considerations Efficiency Ratio 11 Note: The efficiency ratio equals noninterest expense adjusted to exclude amortization of intangible assets, prepayment penalties on long-term debt, impairment of long-lived assets and merger related expenses, divided by the sum of tax equivalent net interest income and tax equivalent noninterest income. To calculate tax equivalent net interest income and noninterest income, the interest earned on tax exempt loans and investment securities and the income earned on bank-owned life insurance has been adjusted to reflect the amount that would have been earned had these investments been subject to normal income taxation. 59.77% 58.75% 59.55% 59.92% 59.08% 56.78% 55.13% 55.33% 52.00% 53.00% 54.00% 55.00% 56.00% 57.00% 58.00% 59.00% 60.00% 61.00% 2Q15 3Q15 4Q15 1Q16 2Q16 3Q16 4Q16 1Q17 Efficiency Ratio Trend Adjusted Tax Equivalent Efficiency Ratio 

12 Guaranty Bancorp – Investment Considerations Operating Earnings1 ($ in thousands) 1 See accompanying reconciliation of non-GAAP financial measurements to GAAP. First quarter 2017 Operating Earnings of $9.8 million compared to $6.2 million in first quarter 2016, a 57.6% increase 92.4% growth $3,000 $4,000 $5,000 $6,000 $7,000 $8,000 $9,000 $10,000 2Q15 3Q15 4Q15 1Q16 2Q16 3Q16 4Q16 1Q17 Operating Earnings 

Guaranty Bancorp Key Financial Measures: Guaranty Bancorp - Investment Considerations 13 1 See accompanying reconciliation of non-GAAP financial measurements to GAAP. 2 The efficiency ratio equals noninterest expense adjusted to exclude amortization of intangible assets, prepayment penalties on long-term debt, impairment of long-lived assets and merger related expenses, divided by the sum of tax equivalent net interest income and tax equivalent noninterest income. To calculate tax equivalent net interest income and noninterest income, the interest earned on tax exempt loans and investment securities and the income earned on bank-owned life insurance has been adjusted to reflect the amount that would have been earned had these investments been subject to normal income taxation. Three Months Ended March 31, December 31, March 31, 2016 2016 2017  (Dollars in thousands, except per share amounts) Return on average assets - operating1 1.06% 1.13% 1.18% Return on average assets  1.00% 0.88% 1.18% Return on average equity – operating 1 11.19% 10.70% 11.16% Return on average equity  10.50% 8.41% 11.17% Earnings per common share - diluted - operating1 $0.29 $0.34 $0.35 Earnings per common share - diluted $0.27 $0.26 $0.35 Net interest margin 3.60% 3.58% 3.65% Efficiency ratio - tax equivalent 2 59.92% 55.13% 55.33%

Income Statement 2Q15 3Q15 4Q15 1Q16 2Q16 3Q16 4Q16 1Q17 Net Interest Income $18,940 $19,406 $19,856 $19,995 $19,821 $22,750 $27,822 $28,172 Provision (credit) for Loan Losses 113 14 (8) 16 10 27 90 5 Noninterest Income 4,404 4,399 4,262 4,178 4,142 4,705 6,232 6,402 Noninterest Expense 14,956 14,866 15,247 15,792 15,134 18,624 23,237 20,529 Tax Expense 2,798 2,923 2,988 2,510 3,133 3,039 3,306 4,200 Net Income $5,477 $6,002 $5,891 $5,855 $5,686 $5,765 $7,421 $9,840 Operating Earnings $5,586 $5,983 $5,830 $6,238 $6,049 $7,281 $9,445 $9,832 Balance Sheet 6/30/15 9/30/15 12/31/15 3/31/16 6/30/16 9/30/16 12/31/16 03/31/17 Cash and Equivalents $55,169 $23,750 $26,711 $31,142 $30,446 $163,908 $50,111 $40,513 Time Deposits with Banks - - - - - 504 254 254 Investments 442,794 433,299 424,692 400,890 369,008 562,091 590,856 584,746 Loans 1,668,658 1,726,151 1,814,536 1,830,246 1,898,543 2,412,999 2,519,138 2,570,750 Allowance for Loan Losses (22,850) (22,890) (23,000) (23,025) (23,050) (23,300) (23,250) (23,175) Other Assets 125,765 125,320 125,586 122,963 120,068 230,063 229,318 226,563 Total Assets $2,269,536 $2,285,630 $2,368,525 $2,362,216 $2,395,015 $3,346,265 $3,366,427 $3,399,651 Deposits $1,741,999 $1,847,329 $1,801,845 $1,872,717 $1,847,361 $2,752,112 $2,699,084 $2,765,630 Other Liabilities 313,698 219,498 345,041 263,980 317,696 242,793 314,965 275,183 Total Liabilities $2,055,697 $2,066,827 $2,146,886 $2,136,697 $2,165,057 $2,994,905 $3,014,049 $3,040,813 Stockholders’ Equity $213,839 $218,803 $221,639 $225,519 $229,958 $351,360 $352,378 $358,838 Total Liabilities and Stockholders’ Equity $2,269,536 $2,285,630 $2,368,525 $2,362,216 $2,395,015 $3,346,265 $3,366,427 $3,399,651 Guaranty Bancorp Quarterly Financial Statement Summary 1 ($ in thousands) 14 Includes acquisition expenses of $2,205 Includes acquisition expenses of $3,032

Colorado Market 15

Demographics Colorado National Current Population (July 2016) 1 5,540,545 323,127,513 Historical Population Change (April 2010-July 2016) 1 10.2% 4.7% Median Household Income (2015) 1 $60,629 $53,889 Household Income Change (2010-2015) 1 9.1% 5.4% March 2017 Unemployment Rate 2 2.6% 4.5% Market Data 16 1 US Census Bureau 2 Bureau of Labor Statistics Unemployment by County 2 3/31/17 3/31/16 Denver 2.4% 3.7% Boulder 2.0% 3.1% Larimer 2.1% 3.4% Colorado currently has the lowest unemployment rate in the nation.

.Business Climate .Colorado ranks as the nation’s 3rd best state for business – CNBC 2016 .Colorado’s economy ranks as the 2nd strongest in the nation – CNBC 2016 .Denver ranked 1st for economic success in Area Development’s 2015 Leading Locations study .Denver has the best commercial real estate market in the country – Coldwell Banker 2015 .Denver is the best city for investment in residential real estate – HomeVestors 2015 .Colorado ranks 4th in the country for the number of new businesses created – Entrepreneur 2015 .Growth .Denver ranks 1st in Best Places for Business and Careers – Forbes 2016 .Denver ranks 1st in Best Places to Live Rankings – U.S. News and World Report 2016.Colorado’s population is projected to grow by 13.4% from 2010 through 2020 versus an estimated national growth rate of 7.1% - USA Today 2015 .Highly Educated Workforce .Colorado ranks 1st for its high quality workforce – CNBC 2016 .Colorado ranks as the nation’s 2nd most highly educated state – U.S. Census Bureau 2016 .Boulder ranks 3rd for college graduates in STEM (Science, Technology, Engineering, Math) – NerdWallet 2015 Market Data 17

18 Market Data – Largest Metro Denver Employers Company 1 Industry1 1 HealthONE Corporation Healthcare 2 SCL Health System Healthcare 3 Centura Health Healthcare 4 Lockheed Martin Corporation Aerospace & Defense Related Systems 5 CenturyLink Telecommunications 6 Kaiser Permanente Healthcare 7 Comcast Corporation Telecommunications 8 Children's Hospital Colorado Healthcare 9 United Airlines Airline 10 University of Colorado Health Healthcare, Research 11 Wells Fargo Bank Financial Services 12 DISH Network Satellite TV & Equipment 13 IBM Corporation Computer Systems & Services 14 University of Denver University 15 United Parcel Service Parcel Delivery 16 Ball Corporation Aerospace, Containers 17 Frontier Airlines Airline 18 Oracle Software & Network Computer Systems 19 FedEx Corporation Shipment & Logistics Services 20 MillerCoors Brewing Company Beverages 21 Xcel Energy Utilities 22 Level 3 Communications Communication & Internet Systems 23 Raytheon Company Aerospace Systems & Software 24 Boulder Community Hospital Healthcare 25 CH2M Hill Engineering & Architectural Services 1 Metro Denver Economic Development Corporation 2 Colorado Office of Development and International Trade Major Colorado Industries2: •Advanced Manufacturing •Aerospace •Bioscience •Creative Industries •Defense •Electronics •Energy •Financial Services •Food & Agriculture •Health & Wellness •Engineering •Technology •Tourism •Transportation 

19 Market Data – Largest Northern Colorado Employers Company 1 Industry 1 1 University of Colorado Health Healthcare 2 JBS Swift & Company Beef Processing/Corporate Office 3 Banner Health: North Colorado Medical Center Healthcare 4 State Farm Insurance Companies Insurance 5 Hewlett Packard Technology Product Design 6 Center Partners Customer Care Center 7 Woodward Speed Controls 8 Banner Health: McKee Medical Center Healthcare 9 Vestas Wind Turbine Manufacturing 10 Hallliburton Energy Services, Inc. Oil & Gas Development 11 Hach Company Analytical Instruments 12 Avago Technologies Semiconductor Components 13 Anheuser-Busch Brewery 14 TeleTech Financial Services Support 15 Anadarko Petroleum Oil & Gas Development 16 Advanced Energy Semiconductor Components 17 Otterbox Protective Case Manufacturing 18 Afni, Inc. Business Solutions 19 Carestream Health, Inc. Medical & Dental Imaging 20 Select Energy Services Oil & Gas Development 1 Metro Denver Economic Development Corporation 2 Colorado Office of Development and International Trade  Major Colorado Industries 2: •Advanced Manufacturing •Aerospace •Bioscience •Creative Industries •Defense •Electronics •Energy •Financial Services •Food & Agriculture •Health & Wellness •Engineering •Technology •Tourism •Transportation 

Reconciliation of Non-GAAP Financial Measures 20

Tangible Book Value as of March 31, 2017 Stockholders’ Equity  $358,838 Less Goodwill and other Intangible Assets  (71,072) Tangible Common Equity  $287,766 Shares Outstanding 28,393,278 Book Value per common share  $12.64 Tangible Book Value per common share $10.13 Tangible Common Equity Ratio as of March 31, 2017 Stockholders’ Equity  $358,838 Less Goodwill and other Intangible Assets  (71,072) Tangible Common Equity  $287,766 Total Assets $3,399,651 Less Goodwill and other Intangible Assets  (71,072) Total Tangible Assets  $3,328,579 Equity Ratio – GAAP1 10.56% Tangible Common Equity / Tangible Assets 8.65% 1 Total stockholders’ equity / total assets  Guaranty Bancorp Reconciliation of Non-GAAP Financial Measures ($ in 000s, share data excepted) 21

Operating Earnings 2Q15 3Q15 4Q15 1Q16 2Q16 3Q16 4Q16 1Q17 Net Income $5,477 $6,002 $5,891 $5,855 $5,686 $5,765 $7,421 $9,840 Expenses adjusted for: Other real estate owned (gain) 54 (31) 16 2 5 20 4 68 Merger related expenses - - - 675 347 2,205 3,032 - Impairment of long-lived assets 122 - - - - - 185 190 Prepayment penalty - - - - - - - - Income adjusted for: (Gains) Losses on Security sales - - (132) (45) 101 66 (49) - (Gain) Losses on other asset sales - - 18 (14) - - - (271) Pre-tax earnings adjustment 176 (31) (98) 618 453 2,291 3,172 (13) Tax effect of adjustments (67) 12 37 (235) (90) (775) (1,148) 5 Tax effected earnings adjustment 109 (19) (61) 383 363 1,516 2,024 (8) Operating Earnings $5,586 $5,983 $5,830 $6,238 $6,049 $7,281 $9,445 $9,832 Average Assets $2,199,723 $2,268,603 $2,327,224 $2,359,180 $2,356,964 $2,613,133 $3,336,143 $3,374,153 Average Equity $213,545 $216,742 $221,515 $224,179 $228,060 $253,570 $351,251 $357,288 Fully diluted weighted average shares outstanding 21,200,438 21,224,989 21,303,763 21,398,559 21,378,349 22,984,647 28,043,944 28,090,179 Diluted EPS – Operating $0.26 $0.28 $0.27 $0.29 $0.28 $0.32 $0.34 $0.35 Diluted EPS – GAAP $0.26 $0.28 $0.28 $0.27 $0.27 $0.25 $0.26 $0.35 ROAA – Operating 1.02% 1.05% 0.99% 1.06% 1.03% 1.11% 1.13% 1.18% ROAA – GAAP 1.00% 1.05% 1.00% 1.00% 0.97% 0.88% 0.88% 1.18% ROAE – Operating 10.49% 10.95% 10.44% 11.19% 10.67% 11.42% 10.70% 11.16% ROAE - GAAP 10.29% 10.99% 10.55% 10.50% 10.03% 9.04% 8.41% 11.17% 22 Guaranty Bancorp Reconciliation of Non-GAAP Financial Measures ($ in 000s, share data excepted)