Free IT tools
Quick answers for everyday IT questions. Pick a tool, fill in the boxes, and the answer updates as you type. Everything runs in your browser; nothing you type is sent to us.
New: check whether someone can fake your company email (SPF, DKIM, DMARC and BIMI), or look up any domain’s registrar, web host and renewal date.
Subnet calculator
Enter an IPv4 address with its prefix (e.g. 192.168.10.25/24), or an address and a subnet mask.
Download time
How long a file, backup or cloud migration takes at a given internet speed.
time = size × 8 ÷ (speed × efficiency)
Office internet
A rough guide to the internet speed your office needs at its busiest moment.
per person ≈ 2 Mbps · HD video call ≈ 4 Mbps down / 3 up · VoIP ≈ 0.1 · heavy cloud ≈ 25 · camera ≈ 2 up; +30% headroom
Storage & RAID
Usable space and how many drives can fail, for a server or NAS.
RAID 5 = (n−1) × size · RAID 6 = (n−2) × size · RAID 1/10 = n ÷ 2 × size · 1 TB ≈ 0.909 TiB (what Windows shows)
Backup size
How much backup storage you need to keep daily versions for a number of days (incremental backups).
(full copy + daily change × days) × (1 − saving) · keep a second copy off site (3-2-1 rule)
Uptime & SLA
What an uptime percentage really allows in downtime.
Password strength
Describe a password (don't type a real one here) to see how long guessing it could take.
combinations = (character set size)length · time for half of them at the chosen speed. Real passwords made of words or patterns are much weaker; turn on multi-factor sign-in.
Cost of downtime
What an hour without computers, email or internet costs your business.
Data conversions
Type in either box and the other one updates.
Please note: these tools give estimates for planning. Real networks, drives and attackers vary; ask us before you buy hardware or sign an internet contract based on them.
Planning a new network, server or cloud move? We'll size it, set it up and look after it.
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