Runtime costs 84% less than Modal for an agent that waits on a model. 100,000 one-minute runs of a 2 vCPU, 4 GiB sandbox, each using 20 CPU-seconds, cost $63.89 a month on Runtime and $396.60 on Modal, $332.71 less. Runtime needs no CPU request sized in advance: it bills what your code uses. Rates checked 25 October 2026.
How Modal bills
Modal publishes per-second rates. A sandbox is billed for whichever is higher, the CPU and memory it requested or what it used, so a requested core is billed while it waits. Modal counts CPU in physical cores, and one physical core is two vCPUs.
| Meter | Modal, as published | Converted |
|---|---|---|
| CPU | $0.00003942 per physical core-second | × 3,600 = $0.1419 per core-hour, $0.0710 per vCPU-hour |
| Memory | $0.00000667 per GiB-second | × 3,600 = $0.0240 per GiB-hour |
For 2 vCPUs (one core) and 4 GiB that is $0.1419 + $0.0960 = $0.2380 an hour, busy or not. Runtime charges $0.025 per vCPU-hour of measured CPU, floor a twentieth of a vCPU, and $0.0075 per reserved GiB-hour: $0.03125 an hour waiting and $0.08 an hour fully busy.
Example workloads
A month of each, CPU and memory only, from the calculator above.
| Workload | Runtime | Modal |
|---|---|---|
| Agent runs: 2 vCPU, 4 GiB, 60 s, 20 CPU-seconds, 100,000 a month | $63.89 | $396.60 |
| Every CPU busy: 2 vCPU, 4 GiB, 60 s, 120 CPU-seconds, 100,000 | $133.33 | $396.60 |
| Chat code sessions: 2 vCPU, 4 GiB, 5 min, 30 CPU-seconds, 20,000 | $54.17 | $396.60 |
| Data analysis: 4 vCPU, 16 GiB, 60 min, 2,880 CPU-seconds, 2,000 | $280.00 | $1,336.03 |
The chat-session row shows the difference most clearly. Five-minute sessions that use 30 CPU-seconds each cost Modal the same as one-minute runs, because it bills the request for the whole session. On Runtime they cost $54.17, 86% less. With every CPU busy, Runtime still saves 66%.
A smaller CPU request lowers Modal's figure, but it also caps what the sandbox can use when it needs more. Runtime has no request to trade off: a sandbox can use every vCPU it has and pays only for what it used.
Modal sandboxes run for up to 24 hours, with snapshots to carry state beyond that. A Runtime sandbox has no time limit. It runs while it works, so a long session is priced the same way as a short one: by the CPU it used and the memory it reserved.
What the calculator leaves out
- Plan fees. Modal's Starter plan is $0 and includes $30 of compute a month. The Team plan is $250 a month. Runtime has no plan, only prepaid credit from $10.
- Free credit. The calculator does not subtract Modal's $30 a month of Starter compute. It prices list rates. Runtime includes 100 free hours of a 1 GB machine on the free trial, no card.
- Storage and network. Left out on both sides. A paused Runtime sandbox keeps its files, memory and running processes for $0.08 per GB a month.
Price your own runs exactly
The CLI prices the sandboxes you have run on Runtime at Modal's published rates, using the same vCPUs, memory and running time:
Terminalruntime compare --from modalIt reads the last 30 days of settled sandboxes (--days up to 90) and says
what you save a month. Credit you add within 30 days of signing up is matched, up to $1,000 in total (welcome match).
The rest of the comparison, isolation included (Modal uses gVisor; Runtime a microVM with its own kernel), is in Runtime vs Modal. Modal alternatives, E2B vs Modal and Modal vs Vercel Sandbox compare it with the others.
Sources
- Modal pricing, checked 25 October 2026
- Modal resources and billing
- Runtime pricing
Rival rates on this page were checked on 25 October 2026.