Calculators built for
sysadmins & network engineers
No sign-up, no clutter — just fast, accurate tools for the numbers you check every day.
Subnet Calculator
IPv4 CIDR, subnet mask, network/broadcast address, usable host range, and wildcard mask — instantly.
RAID Calculator
Usable capacity, redundancy, and fault tolerance for RAID 0, 1, 5, 6, 10 and more.
SLA Uptime Calculator
Convert any SLA percentage (99.9%, 99.99%, 99.999%...) into allowed downtime per year, month, week and day.
Bandwidth Calculator
Estimate file transfer time from file size and link speed, or convert between Mbps/MB/GB units.
DNS Propagation & TTL Calculator
Convert TTL into human-readable time, estimate propagation windows, and plan migration cutover timing.
Backup Retention & 3-2-1 Calculator
Calculate total backup storage for your retention window and the full footprint for a 3-2-1 strategy.
MikroTik Firewall Rule Generator
Generate RouterOS 6/7 firewall rules — input hardening, bogon blocking, port forwarding, FastTrack, VPN passthrough.
Cron Expression Calculator
Paste a cron expression to get a plain-English explanation and the next scheduled run times.
Network & Email Tools
DNS Lookup, SPF Record Generator, and DMARC Record Generator — real queries and real records.
Why CalcLoop
Most "online calculator" sites are built for generic traffic — slow, ad-heavy, and vague on the details that matter. CalcLoop is built the other way around: every tool targets a specific task an infrastructure engineer runs into during provisioning, capacity planning, or SLA negotiation, with clear output you can paste straight into a ticket, runbook, or contract review.
Everything on this site runs client-side in your browser. No data you enter is sent anywhere or logged.