Cost by Size / 100 Employees

Payroll cost for 100 employees: mid-market pricing and the in-house break-even

At 100 employees, the small-business payroll category gives way to the mid-market HCM category. The Gusto Simple price-per-seat math no longer applies cleanly because the providers worth evaluating are quote-only HCM platforms (Paylocity, ADP Workforce Now, Paychex Flex Pro, Rippling at scale). The PEO conversation peaks here, and the in-house HR plus dedicated HRIS configuration becomes a real alternative for the first time. This page works through the full landscape.

Nine options at 100 employees

Estimated monthly cost across the realistic configurations at this size. All numbers exclude benefits premiums (which pass through to carriers), workers' compensation premiums (which vary by industry), and any one-off implementation fees. Quote-only providers are estimated from G2 and TrustRadius aggregated buyer data through Q1 2026.

Option	Monthly cost	Notes
Rippling (payroll + HR)	$1,835	Payroll plus HR core modules. Excludes IT, identity, benefits add-ons.
Paylocity (est.)	$1,000	Quote-only mid-market HCM. $650-$1,300 typical buyer range.
Paychex Flex Pro (est.)	$1,100	Mid-market Paychex with HR support and workers' comp.
ADP Workforce Now (est.)	$1,800	Quote-only mid-market HCM. $1,500-$2,500 typical buyer range.
Gusto Premium (est.)	$2,300	Quote-only. Beyond Gusto's published tier. Roughly $11-$25 per emp.
Justworks Plus with Benefits	$15,900	PEO model with full HR plus benefits plus workers' comp.
Insperity (est.)	$7,000	Mid-range PEO estimate with dedicated HR consultant.
ADP TotalSource (5% of payroll)	Variable	At $60k avg salary, ~$25k monthly. Higher salaries push much higher.
In-house HR + Rippling	$12,500	Mid-level HR generalist ($90k salary + benefits ~$10.5k monthly) + Rippling $1,835.

The four configurations to evaluate at 100 employees

The 100-employee decision essentially splits into four configurations. First, mid-market HCM without in-house HR: ADP Workforce Now or Paylocity at $1,500 to $2,500 monthly, with operational HR work distributed across managers plus a part-time consultant. This is the cheapest configuration but requires HR maturity from line managers.

Second, integrated platform plus fractional HR: Rippling at $1,800 to $3,500 monthly plus a fractional CHRO at $3,000 to $6,000 monthly. Total $4,800 to $9,500 monthly. This is the modern tech-stack approach for businesses that value automation and unified data but are not ready for a full-time HR director.

Third, PEO: Justworks at $15,900 monthly, Insperity at roughly $7,000, TriNet at $12,000 to $20,000, or ADP TotalSource on percentage pricing (highly variable by salary). The PEO consolidates everything in a single relationship at higher monthly cost but lower internal HR overhead. Best for businesses that explicitly do not want to hire dedicated HR.

Fourth, in-house HR plus HRIS: a $90,000 salary HR generalist (fully loaded around $10,500 monthly including benefits and overhead) plus Rippling at $1,835 monthly equals roughly $12,500 monthly. This delivers dedicated full-time HR attention, deeper organisational knowledge over time, and ownership of the people function in a way that PEOs and fractional consultants do not match.

The PEO to in-house HR crossover

For decades the PEO model dominated the 50 to 200 employee band because dedicated HR was too expensive at that scale. The math has shifted. HRIS platforms (Rippling, BambooHR, Paylocity, ADP Workforce Now) now provide most of the operational tooling that PEOs bundled. Fractional CHRO services have professionalised and become available at $3,000 to $6,000 monthly. Benefits brokers compete aggressively for mid-market business and provide much of the carrier negotiation leverage that PEOs once monopolised.

At 100 employees, the in-house HR plus HRIS configuration at $12,500 monthly is now genuinely competitive with PEO pricing in the $15,000 to $20,000 range. The in-house HR director knows your business, your culture, your specific operational challenges in ways no PEO consultant can. The HRIS gives you the operational tooling. The benefits broker gives you carrier leverage. The fractional CHRO can fill specialised gaps (executive coaching, complex compensation design, M&A integration) on demand.

The PEO remains the right answer when the business explicitly does not want to manage HR operationally and is willing to pay the premium for that simplicity. For businesses willing to invest in HR capability, the in-house path typically wins on cost and on long-term capability development.

The mid-market quote process and its leverage

ADP Workforce Now, Paylocity, Paychex Flex Pro, and even Rippling at this size are sold through a quote process rather than self-service. The 100-employee buyer who runs parallel quote processes with at least three of these providers reliably gets 15 to 25 percent below the opening price on the winning bid. The buyer who picks the first reasonable quote pays $20,000 to $50,000 per year more than necessary.

The most effective negotiation tactic is the parallel quote with shared module list. All four providers can configure to roughly equivalent scope. Asking each to quote against the exact same configuration takes 4 to 8 weeks of sales conversations but produces directly comparable numbers. Show each vendor the lowest competing quote and most will sharpen pencils significantly.

Contract length is the second lever. 24-month commitments typically discount 5 to 15 percent on the per-employee fee. 36-month commitments discount 10 to 20 percent but lock you in longer. The trade-off depends on confidence in growth trajectory and the platform fit, which is genuinely hard to judge in advance.

Industry-specific considerations at 100 employees

At 100 employees, industry-specific compliance starts driving meaningful cost differences. A construction firm with prevailing wage projects benefits from Paychex's certified payroll capability or ADP's. A healthcare clinic with multiple pay rates and shift differentials benefits from OnPay's or Rippling's native handling. A multi-state field service operation benefits from any provider with strong multi-state automation but particularly from ADP's pre-built state compliance reporting.

For tech-adjacent businesses without industry-specific complexity, Rippling's unified platform value compounds at this scale. For industries with significant compliance overhead, the more traditional providers (ADP, Paychex) often deliver better specialised capability per dollar. The construction payroll cost guide covers one of the highest-complexity industries in depth.

Where to go next

Payroll cost for 25 employees

The smaller size band where the decision is simpler.

ADP cost

Workforce Now territory at this size, plus the Run-to-WFN transition.

Paylocity cost

ADP Workforce Now's most direct mid-market competitor.

Insperity PEO cost

The PEO most often cheaper than competitors at this scale.

100-employee payroll cost FAQs

What is the cheapest payroll option for 100 employees?

Rippling payroll plus HR at roughly $1,835 monthly is the lowest among integrated HCM platforms. Paychex Flex Pro at an estimated $1,100 is cheaper but covers a narrower scope. ADP Workforce Now at $1,500 to $2,500 is the mid-market workhorse. PEOs land $7,000 to $16,000 monthly for the same headcount. The cheapest option depends on what you actually need beyond payroll, where HR plus benefits administration plus compliance can quickly close the gap between standalone payroll and integrated HCM.

When does in-house HR plus a dedicated HRIS become the right answer?

When the company has grown to a size where dedicated HR leadership delivers value beyond what a PEO consultant can provide. A 100-employee company with a $90,000-salary HR generalist plus Rippling at $1,835 monthly is roughly $12,500 monthly all-in. Justworks Plus with Benefits is $15,900 monthly. The in-house HR option costs less and provides dedicated full-time attention rather than a fractional success consultant. The crossover from PEO to in-house HR is typically around 75 to 150 employees.

Is ADP TotalSource viable at 100 employees?

Depends on salary level. For a 100-employee company averaging $40,000 salary, ADP TotalSource at 5 percent is $16,667 monthly, competitive with Justworks Plus with Benefits at $15,900. For a 100-employee company averaging $80,000 salary, ADP TotalSource at 5 percent is $33,333 monthly, dramatically more expensive than Justworks at $15,900 or in-house HR plus Rippling at $12,500. Higher-salary 100-employee companies should not pick percentage-of-payroll PEOs.

Why is Rippling so much cheaper than Paylocity at this size?

The Rippling figure here is payroll plus HR core only, where Paylocity quote-based pricing typically includes more modules in its bundle. With the same module mix (payroll, HR, benefits, time, talent), Rippling at 100 employees lands closer to $2,500 to $4,000 monthly, similar to Paylocity. The headline comparison depends entirely on configuration scope. Get parallel quotes with the same module list to make fair comparisons.

What does Workforce Now implementation cost at 100 employees?

ADP Workforce Now implementation for a 100-employee company typically runs $7,500 to $25,000 one-off, with a 60 to 90 day deployment cycle. Implementation fees are negotiable, especially on 24 or 36 month contracts where ADP frequently waives them. Paylocity implementation is similar at $5,000 to $15,000. Rippling implementation is typically free for direct customers but premium implementation with a dedicated consultant runs $5,000 to $10,000.

How do annual price increases work at 100 employees?

Most quote-based providers (ADP, Paychex, Paylocity) default to 3 to 7 percent annual price increases unless explicitly negotiated to a price hold. For a 100-employee company at $2,000 monthly, a 5 percent annual increase is $1,200 in year-two annual cost growth. Negotiating a 2 to 3 year price hold as part of the initial contract can save $5,000 to $15,000 over the contract life. Most buyers underestimate the negotiation room on this lever.

What does workers' comp cost on top of these numbers?

Workers' compensation premiums depend entirely on industry class codes and state SUI rates. For 100-employee office-based businesses, workers' comp typically runs 0.5 to 2 percent of payroll. For 100-employee construction or manufacturing operations, it can run 5 to 15 percent. These premiums are pass-through to the carrier on standalone payroll providers, included in the PEO fee on Justworks and similar, and consolidated in ADP TotalSource's percentage. The PEO advantage on workers' comp is real for higher-risk industries because of the pooled risk pricing.