AWS ALB vs NLB Cost Calculator
Load balancers don't bill by throughput. They bill by LCU — Load Balancer Capacity Units — and you pay for the single largest dimension, not the sum of them. A balancer pushing 2 Gbps but only 5 new connections/sec still bills 2 LCU, because bandwidth is the binding dimension. ALB and NLB price LCU differently ($0.008 vs $0.006) and count dimensions differently (ALB caps at 25 new connections/LCU; NLB tolerates 800). This calculator models both against your exact traffic: new connections, active connections, bandwidth, and — for ALB — rule evaluations beyond the first 10. Then it puts ALB and NLB head to head.
📐 Traffic Profile
Describe your load balancer's steady-state traffic. The engine computes LCU for both ALB and NLB from the same numbers and shows which dimension binds each. All four LCU dimensions are evaluated; the max wins.
📋 ALB / NLB LCU & Pricing Reference (2026)
One LCU = the smaller of the two capacities per dimension. You are billed for the MAX of the dimensions, rounded up. Fixed hourly is per load balancer. us-east-1 baseline; other regions vary ±10%.
| Dimension | ALB per LCU | NLB per LCU |
|---|---|---|
| New connections / flows per sec | 25 | 800 (TCP) |
| Active connections / flows | 3,000 | 100,000 |
| Bandwidth | 1 Gbps | 1 Gbps |
| Rule evaluations per sec (ALB) | 1,000 | — |
| New TLS flows per sec (NLB) | — | 50 |
| Source/dest IP tuples (NLB) | — | 240,000 |
| Price per LCU-hour | $0.008 | $0.006 |
| Fixed per LB-hour | $0.0225 | $0.0225 |
ALB rule evaluations count only rules evaluated beyond the first 10 free rules. NLB bandwidth per LCU is 1 Gbps for both TCP and TLS. Source: AWS Pricing Calculator, July 2026. Verify against your region.
The Dimension You're Not Watching Is the One You Pay For
Most teams size a load balancer by "how much traffic" and stop. But LCU billing doesn't care about your gut feel — it cares about four independent dimensions, and bills you for whichever is largest. Get the largest one wrong and you either over-provision (paying for LCU you don't use) or, worse, you assume NLB is always cheaper and miss that ALB's rule-evaluation dimension is silently the binding constraint on a path-based routing setup.
1. "Pay for the Max, Not the Sum" — The Core Rule
Four dimensions are computed. The LCU count is the ceiling of the maximum, not the total. A balancer at 2 Gbps, 5 new conn/s, 3,000 active, 100 rule-evals/s computes LCU = max(2/1, 5/25, 3000/3000, 100/1000) = max(2, 0.2, 1, 0.1) = 2 LCU. Bandwidth binds. Doubling active connections to 6,000 (2 LCU) or adding 50 rules (still 0.05 LCU) changes nothing — you're already capped by bandwidth. This is why throwing more rules at an ALB usually costs $0 until you cross a dimension boundary. The calculator shows you exactly which dimension is binding so you know what actually moves the bill.
2. The Rule-Evaluation Gotcha (ALB Only)
ALB counts rule evaluations at 1,000 per LCU-second — but only for rules evaluated beyond the first 10. Ten free rules is a lot; most simple path-based setups never cross it. The moment you do — 50 content-based rules on a 2,000 rps endpoint evaluates 2,000 × 40 = 80,000 rule-evals/s = 80 LCU from rules alone, which can become the binding dimension even when bandwidth is modest. This is the trap: a URL-rewrite-heavy ALB can bill more in rule LCU than in bandwidth LCU. NLB has no rule concept at all — another reason NLB wins pure L4 workloads.
3. ALB vs NLB — When Each Wins
| Need | Use ALB when… | Use NLB when… |
|---|---|---|
| HTTP routing | Path/host-based rules, redirects, auth, gRPC, WebSocket upgrade | Not applicable — L4 only |
| Connection rate | Fine up to ~tens of k new conn/s before LCU explodes | 800 new flows/LCU — absorbs hundreds of k/s cheaply |
| Latency | +1 rule = +~1ms (see ALB Rule Latency Inspector) | Lowest latency, no HTTP parsing, static IP option |
| Cost at high conn | Pricier per connection | Up to 32× cheaper on connection-bound workloads |
| TLS termination | Native, offloaded | Supported, adds TLS-flow LCU dimension |
4. The Fixed Hourly Floor
Every load balancer costs $0.0225/hr = $16.43/month before a single request. Two balancers in two AZs for HA = $32.86/mo floor. At low traffic this fixed cost dominates — a dev ALB serving 5 rps still costs ~$16/mo. If you're running multiple ALBs for marginal traffic, consolidating behind one ALB with host-based routing (free rules!) often cuts the fixed floor in half. The calculator's fixed-vs-LCU split makes this visible.
5. Who Should Care Most
| Profile | Typical Monthly Bill | What This Calculator Reveals |
|---|---|---|
| Small API / internal | $16–40/mo | Fixed hourly floor dominates. One ALB, host-based routing beats three separate ALBs. NLB unlikely to help at this scale. |
| Standard web app | $40–200/mo | Bandwidth usually binds. ALB vs NLB within 25%. Rule count matters only if you exceed 10 content rules at high rps. |
| Connection-heavy (games, MQTT, IoT) | $200–2,000/mo | New-connection dimension binds. NLB is dramatically cheaper — 32× more efficient per LCU. Switching can cut the bill 3–5×. |
| Rule-heavy edge router | $150–1,000/mo | Rule-eval LCU can become binding. Audit rule count; NLB can't do the routing, so the fix is rule consolidation, not LB swap. |
Pricing Basis, Sources & Assumptions
Every rate on this page is a published vendor list price — no negotiated discounts, private pricing, or credit offsets. Totals are in USD and exclude tax. Rates were last checked against the sources below on .
| Pricing input | Basis used on this page |
|---|---|
| Region | us-east-1 (N. Virginia). Regional ALB and NLB rates differ — re-check the linked pricing page for other regions. |
| Currency | USD — on-demand list price, tax excluded |
| Last checked | — Load balancer and LCU rates are carried from the linked AWS pricing page; the LCU dimension definitions were re-checked on this date. |
Modelling assumptions
- 730 hours per month. Both ALB and NLB are billed a fixed $0.0225 per load-balancer-hour, which applies even at zero traffic.
- ALB capacity units are $0.008 per LCU-hour; NLB capacity units are $0.006 per NLCU-hour.
- An LCU is the maximum of its dimensions, not the sum: for ALB that is 25 new connections/s, 3,000 active connections/min, 1 GB/h processed, and 1,000 rule evaluations/s. For NLB the data dimension is 1 Gbps per NLCU.
- Only rule evaluations beyond the first ten are metered, which is why adding rules is usually free until a dimension boundary is crossed.
What this model excludes
- Cross-AZ data transfer between the load balancer and its targets, which is billed separately at $0.01/GB in each direction.
- AWS WAF, Shield Advanced, Global Accelerator, and Gateway Load Balancer.
- ACM public certificates (no charge), CloudWatch metrics beyond the free tier, and LCU reservations or private pricing.
Sources
- AWS (2026). "Elastic Load Balancing Pricing." ALB and NLB per-hour, per-LCU-hour, and per-NLCU-hour rates. aws.amazon.com
- AWS (2026). "Load Balancer Capacity Units (LCU)." The four LCU dimensions and how the highest one sets the charge. docs.aws.amazon.com
- AWS (2026). "Listeners for your Application Load Balancers." Rule evaluation ordering — why only evaluations past the first ten count toward LCUs. docs.aws.amazon.com
Vendor list prices change without notice — re-check the linked pages before committing spend. jslet takes no vendor sponsorship and carries no affiliate links; see about.